Fox T-Bird/Cougar Forums

Technical => Engine Tech => Topic started by: Masejoer on October 07, 2019, 07:14:26 PM

Title: Troubleshooting persistent misfire
Post by: Masejoer on October 07, 2019, 07:14:26 PM
Cross post from corral.net, where I've received no ideas from anyone.

This will be a long post so that I can lay out what I can think of in terms of powertrain parts, and what I've tested already. I have made followup replies in this thread with powertrain specifications, and what I've tested.

-----------------------------

I recently picked up my decade old project again on "restoration"/re-engineering entire chassis as an updated take on an old fox platform (including CAD/CAM work). This is a 1988 vehicle running mass air, with newer 306 and 4R70W transmission.

Anyway, short disclaimer is that I don't remember exactly how the car ran a decade ago, or even 5 years ago when I drove it to a new house, but I believe I've always had a misfire. This includes iron heads I ran 15 years ago, but memory is extremely fuzzy from that far back, and I knew far less about cars back then. For awhile I also had transmission issues, and spent my time troubleshooting that more than the motor. With a properly working 4R70w in there today, and a 3000 stall Precision Industries converter, all of which runs generally great, I need to sort out some motor drive-ability issues.

-----------------------------

The problem:

I have what sounds like a slight misfire (lean misfire?) - the rpms don't hold steady at idle, or when rev'd to 2k.  This is very noticeable after the engine warms up/AFR comes down, but it's also there when cold, or if I force open-loop via tuning software. The engine isn't as smooth as it should be. Years back I was told that I had flames popping out of open down-pipes, but also later out the tail pipes (with cats) when backing out of the garage, with cold engine. Wideband numbers always look good, and don't report lean conditions when I feel/hear the "misfire".

Video/audio of engine in closed loop, with stock-ish tune and me having EV1 19lb injectors, stock MAF installed:
https://www.youtube.com/watch?v=3b8iIwVc5e8 (https://www.youtube.com/watch?v=3b8iIwVc5e8)


Any ideas of what else I can look at? I need this fixed for my own sanity - a v8 with a stock cam should run smoother than this. I also believe I had the same issue on my previous gt40p heads, different sets of injectors, maf, intake, etc, but it has been way too many years. I'm dospoogeenting my troubleshooting steps this time.


Car runs great otherwise - no WOT performance issues from street driving. Closed loop runs clean. 3.55 gears brought me down to 25mpg highway. 3.08 gears returned 30.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 07, 2019, 07:15:52 PM
My powertrain specifications:

Stock-type 306 rebuild from 15 years ago, 20k miles on the rotating assembly:
TRW-L2305F30 pistons
SLP-E-251K030 rings
SCA-35090P i-beams
Stock 1989 Mustang camshaft
Stock pan, pump, crank machines and balanced with the rotating assembly
Powerbond 50oz SFI balancer
Timing setup dot to dot, and seems correct for TDC marks on balancer for each cylinder when I tried leakdown tests

Rest of engine (newer than shortblock):
TW 170cc heads cut down to 54cc chambers (lots of clearance with 1.7 rockers, clayed)
Comp-cams high energy hydraulic roller lifters set to 0.025 preload
Whatever pushrod length was needed when the heads were initially installed
GT40 tubular intake with lower porrted by tmoss
19lb stock injectors, and 30lb FMS injectors
Stock MAF, and PMAS 75mm "24lb" MAF
Accufab 70mm throttle body
FMS stainless "gt40p compatible" shorty headers with 1-5/8" primaries
Autolite 3924 plugs gaps tested at .040 and.050
MSD spark wires, <100 miles
Stock distributor/TFI, and Richporter FD04 replacement
Standard "195" thermostat
New Motorcraft TPS
New Motorcraft air charge and engine temp sensors
Various gaskets, 9.8:1 static compression ratio.
EGR and IAC still installed
Currently have fresh 92 octane ethanol-free fuel

Drivetrain:
4R70w transmission/stock VB/clutches from 2003 3.8L
Larger capacity trains oil pan with cooling fins
PI Stallion 3000 stall converter
Stock driveshaft
8.8" rear differential with 3.55 gears, 26.6" wheel diameter

Other:
1989 A9P ECU with new capacitors
Quarterhorse tuning board
New Motorcraft fuel regulator
2.5" exhaust, catalytic converters intact (few hundred miles)
Larger, soldered engine grounds with contact areas using NO-OX grease
Dual Innovate LC-2 wideband sensors mounted horizontally near bottom of exhaust down-pipes
DataQ datalogger  for widebands
Young narrowband o2s that sweep well
1/0 gauge alternator power wire, 4awg timing cover to battery ground, 7awg dual braided head to firewall grounds, crimped and soldered terminals

Much of the above hasn't seen more than around 100 miles in over 5 years. A week ago it was driven to a glass shop, and likely doubled the mileage it has seen since being driven to a new house years ago.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 07, 2019, 07:18:52 PM
What I've done/re-tested lately:

- Smoke machine intake test, no leaks with oil filler cap taped down
- Distributor swapped out with a new unit, new TFI, as a test. No change. Caps/rotors still both look new.
- New BAP, TPS, air charge, engine temp sensors
- New IAC
- IAC block off
- Rocker arms checked to ensure preload
- EGR valve tested
- Cleaning of TFI plug
- Cleaned and increased contact tension of the salt and pepper connectors at engine harness
- New battery
- Shaken/wiggling harness connections when running to look for change in idle quality (none)
- 30lb EV6 Injectors flow tested - good.
- Reinstalled some original refurb/flow tested 19lb EV1 injectors to test stock tune.
- MAF seems to sweep fine, but reinstalled stock 1989 MAF to test stock tune.
- Leakdown test shows 8-10% across all cylinders. No sound from intake or exhaust - crankcase only. PHOTO (http://masejoer.com/Images/Thunderbird/Engine/MotorTroubleshooting/leakdown.jpg) PHOTO (http://masejoer.com/Images/Thunderbird/Engine/MotorTroubleshooting/leakdown_list.jpg)
- 165-170psi compression test across all cylinders
- plugged off vacuum lines an pcv, no vacuum at oil filler tube (lower intake gaskets should be good). Slight vacuum at oil filler tube with pcv re-attached.
- no exhaust smoke
- no coolant or oil issues
- stock tune (minus increasing CID to 306, and disabling thermactor) with stock injectors and MAF
- new engine bay grounds with conductive grease
- cleaned and re-mounted eec-iv computer grounds
- timing at 10 degrees base. According to tuning software, issue still exists at all timing so not a timing advance issue
- timing should be correct on balancer - markings seem to match TDC of various cylinders perfectly (for leakdown test). Timing chain doesn't appear to be off.
- no engine running codes. Cylinder balance test comes back as passing
- engine is idling fine at 650-750rpms, around the 672 being commanded. Should be more steady.
- 16in/Hg vacuum at warm idle with all vacuum accessories attached, 1300rpm and above get 20in/Hg
- Coolant temperature is a steady 206-208F at temperature sensor when idling or driving, 160F intake runner temperature at idle in garage
- I've tried completely isolating plug wires into air as a test, but no change
- Spark plugs all look great PHOTO (http://masejoer.com/Images/Thunderbird/Engine/MotorTroubleshooting/sparkplugs.jpg)
- Correct firing order PHOTO (http://masejoer.com/Images/Thunderbird/Engine/MotorTroubleshooting/firingorder.jpg)
- Timing light on each wire doesn't appear to have any missing ignitions. I hoped to find one with occasional missing flashes...
- Replaced capacitors in A9P
- Binary Editor datalogs generally look good - the stumble isn't timing swinging around.
- Idle doesn't improve if I richen up the AFR. Leaner than stoich just starts to stumble, as expected.
- Fuel pressure 40psi without vacuum, 33psi at idle with vacuum. PHOTO (http://masejoer.com/Images/Thunderbird/Engine/MotorTroubleshooting/fuelpressure_novac.jpg) PHOTO (http://masejoer.com/Images/Thunderbird/Engine/MotorTroubleshooting/fuelpressure_idle.jpg)
- New alternator due to failing bearings. New alternator's AC ripple is 29mA.
- EGR block off

Things that I still want to check:
- Replace salt/pepper engine harness connectors with 12-pin deutsch connectors
- New coil again? Years ago I tried a new aftermarket coil, but it would breakup badly at 2500+ rpms. I went back to my old coil.
- Unplug Quarterhorse completely and run stock tune only with stock MAF/injectors
- Exhaust smoke machine test
- Try a completely different A9P?

Other plans:
- EDIS-8 to ditch TFI altogether. Just need a crank pulley to take to machine shop with trigger wheel for welding/balancing
- Install my Lightning MAF, for potential better metering than the aftermarket unit, unrelated to stock air/fuel parts and tune
- Upgrade from 130A alternator to newer 200A, 0awg ground upgrade
- Maybe removing the exhaust to see if my issue has nothing to do with the motor, but ignition in the cats sending waves back up to the motor, messing with cylinder activity?
- New seal on oil filler lid since I get a slight leak under pressure from the smoke machine
Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 07, 2019, 08:42:14 PM
What's your tps set to at CT KOEO? When you replaced the IAC and TPS how did you reset base idle just out of curiosity. Also can you share the datalog .CSV file for binary editor? For when its acting up obviously.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 07, 2019, 10:14:34 PM
You still have the old stock coil? Check there first. Mine was behaving similarly when the MSD coil on the car ped out.

https://youtu.be/91C8ese1LNo

Put a stock replacement Motorcraft coil on and it's been fine since.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 07, 2019, 10:15:42 PM
What's your tps set to at CT KOEO? When you replaced the IAC and TPS how did you reset base idle just out of curiosity. Also can you share the datalog .CSV file for binary editor? For when its acting up obviously.

Binary Editor is reading 0.97V at idle.

Let me fire up the new BE version on my replacement laptop and get some newer datalogs (old laptop has BE2010), and I'll get a new cold to warm garage-idle datalog posted.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 07, 2019, 10:18:47 PM
You still have the old stock coil? Check there first. Mine was behaving similarly when the MSD coil on the car ped out.

https://youtu.be/91C8ese1LNo

Put a stock replacement Motorcraft coil on and it's been fine since.

I thought your issue was a cracked spark plug?

It has a coil that has seemed to work (it may have been replaced 20,000 miles ago, but who knows at this point. A decade ago), but the coil is a part that I didn't have luck replacing a few years back. Rather than get a entirely new coil at what is likely $80-100, I'd prefer to get this EDIS-8 conversion underway.

I was tempted to tap into an inductive sensor and datalog the coil pulses via the dataq, so that I also have that data available to review. I'd really not care if the EDIS conversion simply fixed my issue though.

Edit: Coil from LMR is $60 shipped
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 08, 2019, 12:35:42 AM
You still have the old stock coil? Check there first. Mine was behaving similarly when the MSD coil on the car ped out.

https://youtu.be/91C8ese1LNo

Put a stock replacement Motorcraft coil on and it's been fine since.

I thought your issue was a cracked spark plug?

It has a coil that has seemed to work (it may have been replaced 20,000 miles ago, but who knows at this point. A decade ago), but the coil is a part that I didn't have luck replacing a few years back. Rather than get a entirely new coil at what is likely $80-100, I'd prefer to get this EDIS-8 conversion underway.

I was tempted to tap into an inductive sensor and datalog the coil pulses via the dataq, so that I also have that data available to review. I'd really not care if the EDIS conversion simply fixed my issue though.

Edit: Coil from LMR is $60 shipped

Coil ped out. Plugs ended up being fine. I changed the plugs, it ran fine then started acting up again. Swapped out the MSD coil with the old stock one and the engine ran fine again.

If you're doing the EDIS conversion the coil might be a waste. On the other hand, based on what you have described, this seems like an ignition or electrical problem. There are only so many mechanical things that can cause the issue, and you seem to have checked them all. Do you know anyone local with a Fox you could borrow the ignition coil from to test?
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 08, 2019, 12:50:37 AM
No, I don't do anything with other local 'car people', as most are usually less about vehicle engineering, and more about "mods" to vehicles that often hinder performance, and they don't understand how. Not my type of crowd. A typical truck forum shows the demographic I'm talking about, where these types seem to run rampant.

I'd be curious about a coil, but I've gone down the route of "throw parts and time at it" before with various things. No sense in buying new parts if Ill be changing it up.

Anyone have a stock crankshaft pulley for not-$50? Need to get one for trigger wheel install.
Title: Re: Troubleshooting persistent misfire
Post by: Mikey97D on October 08, 2019, 08:15:21 AM
I'd be curious to see what the ignition spark/wave looks like on an oscilloscope (Sun Performance Scope?).  I never used one but remember the mechanics using it to chase ignition problems to see if it was only one cylinder and what was happening.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 08, 2019, 10:56:35 AM
Is that like an inductive setup? I'd imagine something could be put together, or a timing light hacked up, that would work to read from an oscope. I may put together something this weekend.

I forgot that I shipped my Quarterhorse off to Moates to get the updated revision. I won't be able to get datalogs for a couple weeks until I receive the replacement unit back.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 08, 2019, 12:55:08 PM
Do you have a shop near by that has an oscilloscope? Since you're ditching the TFI system eventually it would be best to scope the current system to see if you can figure out the cause. Is the sheathing of the TFI connector wiring still intact? 

If you can't get to a shop with an oscilloscope I may have a spare ignition coil in the garage. Let me look tonight. If I do you can have it for the cost of shipping, just so you can check and see if the coil is the issue.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 08, 2019, 01:17:37 PM
I have a couple portable 2-channel oscopes (20 and 60MHz), and a benchtop 100MHz 4-channel. Just need to see what type of signals I can probe at, from where, and have an idea of what I'm looking for on the ignition side. I don't normally scope beyond microcontroller work, and low Voltage vehicle signals.
Title: Re: Troubleshooting persistent misfire
Post by: Mikey97D on October 08, 2019, 02:25:50 PM
The ones I remember looked like this but I bet you can do it with a regular scope too.  I'm not an electrical type person so never learn how.  Sorry.
https://www.google.com/search?rlz=1C1GCEA_enUS864US864&sxsrf=ACYBGNQ4knTBFeLShHAsEKBR_jkNLegPJA:1570559048797&q=Sun+Performance+Scope&tbm=isch&source=univ&sa=X&ved=2ahUKEwj57M6xpI3lAhUqTd8KHelaCmUQsAR6BAgOEAE&biw=1920&bih=937
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 08, 2019, 04:50:54 PM
The ones I remember looked like this but I bet you can do it with a regular scope too.  I'm not an electrical type person so never learn how.  Sorry.
https://www.google.com/search?rlz=1C1GCEA_enUS864US864&sxsrf=ACYBGNQ4knTBFeLShHAsEKBR_jkNLegPJA:1570559048797&q=Sun+Performance+Scope&tbm=isch&source=univ&sa=X&ved=2ahUKEwj57M6xpI3lAhUqTd8KHelaCmUQsAR6BAgOEAE&biw=1920&bih=937

Oscilloscopes are great - Voltage over time, with an adjustable time-scale. Just an extension of a point-in-time Voltmeter.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 09, 2019, 09:17:18 PM
If I attach a stethoscope hose perpendicular to the side of my tail pipes, but blocking out open air, the exhaust drone is cut down, but I hear an occasional faint sound like this from the passenger side: https://youtu.be/mW0q_M_sMrw?t=121

Higher tone, sort of a 'tapping on a shot-glass' sound when using the stethoscope.

Nothing on the driver side pipe.

My mid pipe does need to be re-created though (BBK pre-made). It's right up against the transmission pan lip.

Edit:
Best recording I can get - pushed one of my calibration mics into a hose: LINKED MP3 (http://masejoer.com/Audio/PassengerExhaust.mp3)

The recording (1KHz 6dB high pass filter applied, gain applied) is different than to the ear, but this sure sounds like pinging.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 11, 2019, 12:33:55 PM
It sounds like metal hitting something. The exhaust isn't touching anything is it?


If it's not that you could try disabling one cylinder at a time on the bank to see if the noise goes away. At least you would be able to pin point the noise that way.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 11, 2019, 02:06:44 PM
It sounds like metal hitting something. The exhaust isn't touching anything is it?


If it's not that you could try disabling one cylinder at a time on the bank to see if the noise goes away. At least you would be able to pin point the noise that way.

Yeah, this side is the one where the exhaust is right up against the transmission pan's lip. The 4r70w bellhousing is larger than the aod, so clearances on pre-fabbed exhaust pipes are lacking.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 11, 2019, 03:35:27 PM
Yeah, this side is the one where the exhaust is right up against the transmission pan's lip. The 4r70w bellhousing is larger than the aod, so clearances on pre-fabbed exhaust pipes are lacking.

I bet that's what it is. To my ears it sounds like something hitting a pipe and the sound traveling down the pipe.

Have you been able to scope the ignition coil?

Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 11, 2019, 04:17:45 PM
I should be able to oscope some things this weekend, after trying to install some sn95 mustang seat frames with new 03/04 cobra foam and upholstery. Goodbye leaning driver seat!

Also have my new, longer 1/0 power wire here to re-do my current alternator cable for a cleaner install, and using non-set-screw terminals. Lots of time sinks planned for this weekend! Will also look into where I'd like to weld in some thick grounding bars. Been planning on cleaning up all the electrical connections, wire looming, and techflex sheathing for a long time. Been sitting on parts since summer 2012...
Title: Re: Troubleshooting persistent misfire
Post by: 88BlueBird on October 11, 2019, 07:10:45 PM
Make sure you don't have the LH and RH oxygen sensor connectors swapped. I did this inadvertently when installing the 5.0L engine in my car and I fought a rough idle and random cylinder lean condition for a few months before I figured it out.  The car would run great in open loop, but when it warmed up and went into closed loop it would run like , because it was leaning out the wrong side of cylinder banks.  It's an easy mistake because LH and RH connectors are keyed the same, yay Ford  :beatyoass:
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 11, 2019, 07:59:25 PM
Make sure you don't have the LH and RH oxygen sensor connectors swapped. I did this inadvertently when installing the 5.0L engine in my car and I fought a rough idle and random cylinder lean condition for a few months before I figured it out.  The car would run great in open loop, but when it warmed up and went into closed loop it would run like , because it was leaning out the wrong side of cylinder banks.  It's an easy mistake because LH and RH connectors are keyed the same, yay Ford  :beatyoass:

I don't. I did some decade ago and found that the ecu would start to richen up one bank (thinking it was lean), and lean out the other (thinking it was rich). Eventually it'd fail out of closed loop and go open again. These computers really aren't the smartest in terms of things like this, or having functions that don't always have increasing values (computer flat out fails and stalls the engine), but they work.

The o2 sensor thing is really obvious in tuning software! I wish my issue was a simple as that  :frown:
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 13, 2019, 10:52:51 PM
A friend came over today to put two heads together on this.

With the stock ECU/tune, 19lb injectors, and stock MAF. We did some tests and eventually got to revving the engine. Above 4-4.5k, getting some heavy popping out the exhaust after a few seconds, and tach dropping down. Happens with both SPOUT in and out, but seems to be more drastic with the computer advancing the timing (occasional 1k rpm drops instead of 300-400rpm).

Purchased 2 timing lights and chopped them up to test coil wire and individual spark wires. Not seeing missing spark, but the inductive signal being read by the oscope shows some signals being picked up almost half the strength of others, out of the coil itself. Difficult to properly test this though, with the inductive readings. A recording showing some of the signals (ch1 coil, ch2 wire):

At 0:26, it shows the signal zoomed in. 50μs scale has some common 25μs discrepancies, but I have no idea what's normal.
https://www.youtube.com/watch?v=7AjDoco1fQc (https://www.youtube.com/watch?v=7AjDoco1fQc)

We moved to installing new front seat foam and upholstery, and got stalled there also due to needing to get 2 more 12-inch metal rods for hog rings...


Will mess with more and get some datalogs once I have a Quarterhorse back.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 13, 2019, 11:31:07 PM
Hmm. Not sure what a normal scope should look like.

Just had a thought. How are the caps on the computer?
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 14, 2019, 01:05:15 AM
Hmm. Not sure what a normal scope should look like.

Just had a thought. How are the caps on the computer?

"Replaced capacitors in A9P"

Just replaced these weeks ago. A bit of a pain to se off the coating over the board, but it's relatively easy to replace the caps. Didn't change a thing in how the car runs though.

My old caps didn't leak and corrode the board, but I had a couple weak legs.

Would still like to try a completely different EEC.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 14, 2019, 02:31:25 PM
Hmm. Missed the new caps part.

I hate to parts swap but trying a different coil or different computer are kind of on the test list. No light show from the plug wires when it's dark correct?
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 14, 2019, 03:48:38 PM
Technically with a camera and long exposure, light will always show through a spark plug wire. No way around that besides coil-on-plug (or much thicker wires than even my Firecores).

But no, nothing obvious by eye.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 14, 2019, 07:46:45 PM
How's the car's wiring harness? There's nothing odd going on there? No repaired wires? It's got to be some weird electrical thing.

I still wish that you could compare with normal scope readings but I have no idea where you can find those readings to compare.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 14, 2019, 09:28:00 PM
This started to look to be a different issue than what I initially set out to tackle years ago. Installed new coil and my high rpm breakup is gone, and 2k rpm revving is more steady, but I still hear and feel what I believe to be light misfiring,. Really curious if a different distributor/pip/tfi now would help.

Now I need to revise my testing and see what I should re-test now that a failing coil has been replaced.

Will be nice to have m y Quarterhorse back so I can test things via tune changes, and dropping out of closed loop.

I will re-test with oscope at some point to see if the wave forms look different, and more importantly, more consistent. As for oscope itself, using an induction test still means much less than sticking a $2,000+ high-Voltage probe directly to the coil...I won't purchase such a thing.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 14, 2019, 09:37:41 PM
Wiring harness looks good, but potential issues with that ( no idea yet why my idle doesn't purr) is one of the reasons why, in the past, I was close to dropping the $10k to do a coyote conversion...all because of what I see as a poorly running motor. Most others wouldn't care, and for a long time I just did my best to ignore it. "It's an early computer-controlled v8 with now old sensors, harness, etc, and who remembers now how smooth they ran in the 80's"

...but I still want it to idle and rev rock solid. It has a stock '89 HO cam after all - nothing aggressive.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 15, 2019, 01:22:34 AM
Off topic, but it will be nice to have these seats in there soon, without a broken driver side seat back (passenger side bottom with driver side top sitting here protected):

(http://masejoer.com/Images/Thunderbird/Interior/Upholstery/NewSeats.jpg)


Various projects are still underway!
Title: Re: Troubleshooting persistent misfire
Post by: Mikey97D on October 15, 2019, 08:08:12 AM
I am curious about the distributor/tif/pip too. 
Just for S&G's run a temporary extra ground cable to the coil and if that makes no different maybe move it to the EEC and check.
I don't know how these ECM's and coils work.  Is the coil hot the entire time and only controlled by the distributor or is the voltage increased by the computer for the load parameter?
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 15, 2019, 05:47:04 PM
I can do that one of these days - one long 8awg wire hooked to the battery and attached to a test point on the other end would be quick to do, and be a perfectly fine size to test anywhere on the vehicle.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 17, 2019, 10:34:02 AM
Quarterhorse replacement is due for delivery this Friday, so I will be able to test behavior changes via tune post-coil-change this weekend.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 17, 2019, 11:19:04 AM
So you are sourcing another ignition coil for testing?

I assume your first test will be stock 19lb injectors and a stock MAF, then go from there.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 17, 2019, 02:48:36 PM
Per #28, I installed a new coil and it fixed much of my degrading ignition issue, but I'm back now to trying to identify the original problem I've been experiencing for the last decade - smoothing out the idle.

My one problem turned into 2 problems. New coil, I'm back to one problem now.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 17, 2019, 04:32:15 PM
Per #28, I installed a new coil and it fixed much of my degrading ignition issue, but I'm back now to trying to identify the original problem I've been experiencing for the last decade - smoothing out the idle.

My one problem turned into 2 problems. New coil, I'm back to one problem now.

Jebus I missed the new coil part.


I'm surprised that the idle isn't smoother with the stock cam. I have a Comp 266 HR cam in mine and the idle stays steady in a 50-60 rpm window when it's hot. It's set for 650RPM hot in gear and stays between 650-700 rpm (on an Autometer tach).
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 18, 2019, 02:49:59 PM
Sadly no Quarterhorse today - it will be Monday I'm sure. The plane transport to my city was delayed/late last night, and the tracking still doesn't show it being on a truck for delivery. It's in town, but tracking shows it being in the distribution center since 8:15AM.

This means that I won't be able to get datalogs for a full additional week, the following weekend.

Actually, it looks like they shipped this to my house instead of requested office address. I may be receiving it tomorrow.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 18, 2019, 04:59:49 PM
Keep us posted. At this point I want to know what it is just to satisfy my curiosity.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 18, 2019, 05:11:43 PM
Imagine being haunted by it for some 10+ years! It has always ran fine (was daily driving back then), but I can only "just drive it" for so long. Especially now that it's my "toy" car, I want it to run correctly!

I purchased my Quarterhorse in 2010 thinking a tune would help (had a TwEECer before it). No matter what I tried, the tweaking of values in an attempt to improve metering and ignition quality didn't smooth anything out.

Of course I had other driveability issues with my previous 4r70w, which stole my time for awhile. VB, clutches, pressures all looked and tested great for a 13k mile tranny. Had it apart for an output shaft change. This was another issue that I wanted to identify the root cause of, but in the end I completely replaced the transmission and that issue was resolved. Then the car sat untouched for a few years, and here we are today. Idle quality issue persists. I've suspected that it may be related to a part of the harness/electrical, but so far I haven't found an actual problem with it.
Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 18, 2019, 10:43:22 PM
When was the last time you replaced your spark plugs and what gap are they currently at? Have you always used those autolites and are they the stock heat range? They appear to be but just checking. Just grasping at straws for now, hopefully something in the datalog pops out next week.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 18, 2019, 11:24:07 PM
When was the last time you replaced your spark plugs and what gap are they currently at? Have you always used those autolites and are they the stock heat range? They appear to be but just checking. Just grasping at straws for now, hopefully something in the datalog pops out next week.

They have like 100 miles on them.  Maybe 200? Add a few hours of idling, and moving the car around the property. Heads were installed in old house. I drove it on the highway a bit for tuning. Drove it once for gear swap. Drove it from old house to new house. Drove it for transmission swap. Drove it for new front and rear glass. Not much other than that since the topend was changed years back, in which I hoped would improve the motor smoothness. It didn't.

Much of the engine bay as it sits now have nearly no mileage, and the block being the oldest was rebuilt at 228k miles (248k on the odometer now).  The tw170 heads have almost no miles per the above, along with the plugs and wires, waterpump, alternator, power steering pump, battery, throttle body, iac, egr, pcv, and tps sensor. Shortblock had gt40p heads before these, with about 20k miles I put on them as a daily driver. When I had the heads off for head swap, the cylinders still looked new, and was also when I clay'd the ptv clearance, and did some crude injector flow testing to see if any injector was having a problem. Never consumed oil (beyond what pcv fumes suck up into the runners) when I ran the gt40p heads, but I have almost no real mileage experience with the tw170, being that the car sits and all. My legacy troubleshooting started before the new topend parts though.

I don't believe I've had any other plugs on these heads - just these 3924 that were stocked at the parts store and correct for the head, but my idle concern still went back to those iron heads iirc. Years ago I tackled this issue thinking that perhaps my FMS plug wires were bad, so I picked up both these MSD, and other Firecore50's that I haven't even installed yet (those things don't come with the coil wire crimped).

The plugs were at 0.042, but I opened them up to 0.050 when I swapped the injectors to 19lb a couple weeks back. Didn't seem to change anything, but that may be what made my 4k breakup appear with the old coil. I hadn't seen that breakup previously on this coil - just on an Accel coil I tried a few years ago (above 2.5k rpm).

This persistent issue has killed my interest for too many years, and it must end soon! Spending a lot of time and money on the car now, completing other projects that I've been building up in my mind for almost 20 years.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 19, 2019, 09:24:39 PM
Quarterhose did come this afternoon. Will get the car moved over and access into the passenger footwell (and replace passenger seat) tomorrow. Some contact cleaner and I should be good to throw this on again.

(http://masejoer.com/Images/Thunderbird/Engine/MotorTroubleshooting/Quarterhorse.jpg)
Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 20, 2019, 11:49:21 AM
That looks pretty, so reading back through this post looks like you have swapped out a lot of things, as of right now what maf and injectors are on the car and around what afr are you shooting for? You also mentioned youve only changed CID what is your SARCHG at? Im trying to figure out if something is going on in your maf transfer or load scaling. Maybe once you get your computer going you can send me the .bin file. Ive had idle issues in the past ive been able to tune out with idle adjustments but thats not ideal. I feel like you probably want to get to the bottom of it. A good start may be a base idle relearn if you havent already

http://efidynotuning.com/idleair.htm

Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 20, 2019, 12:49:38 PM
That looks pretty, so reading back through this post looks like you have swapped out a lot of things, as of right now what maf and injectors are on the car and around what afr are you shooting for? You also mentioned youve only changed CID what is your SARCHG at? Im trying to figure out if something is going on in your maf transfer or load scaling. Maybe once you get your computer going you can send me the .bin file. Ive had idle issues in the past ive been able to tune out with idle adjustments but thats not ideal. I feel like you probably want to get to the bottom of it. A good start may be a base idle relearn if you havent already

http://efidynotuning.com/idleair.htm



I have the stock '89 Mustang MAF and EV1 19lb pintle injectors that I rebuilt. Prior to a couple weeks ago I had my PMAS 75mm MAF and 30lb injectors, each with their values input. I was hoping to see it run better going back to parts that the computer was configured for out of the box, but no go. I will leave the stock parts on there until this gets solved, if at all.

In the past I've also used 19lb EV6 injectors and 24lb EV6 injectors (the size that the MAF is "calibrated" for).
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 20, 2019, 07:51:49 PM
Won't get to datalogging today, but I did get the QH installed again. Injured 4th finger out of 5 on my right hand with more upholstery work...

J3 all cleaned up and installed with dielectric grease.

(http://masejoer.com/Images/Thunderbird/Engine/MotorTroubleshooting/Quarterhorse-J3clean.jpg)
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 21, 2019, 09:13:50 PM
Here is a 15 minute cold-to-warm datalog.

Binary Editor Log (http://masejoer.com/Projects/Thunderbird/Engine/MotorTroubleshooting/2019_Oct_21_17-47-36.zip)
Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 21, 2019, 10:47:13 PM
The first thing that really pops out at me is the amount of electrical noise that's being picked up, may just be your cable but might be worth looking into. You could scope the tps signal and see if its just as dirty. 90% of the time when I have electrical noise causing issues its due to aftermarket equipment or an alternator. The first thumbnail is from your datalog the second is one from my car a few weeks ago. I'll keep looking but that's the very first thing I see.


Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 22, 2019, 12:16:23 AM
Wow, that version of BE looks so different than my ancient BE2010!

And useful no doubt.

The only aftermarket electronics that I can think of are LEDs in various locations with their own driver boards (all powered off for the datalog), hid ballasts for my headlights (off), Mark VIII electric fan and DCControl PWM controller (not sure it ever turned on for this datalog), my old Viper alarm, Baumann 4r70w computer and innovate wideband, and the Quarterhorse Alternator was just replaced and it didn't change how the car ran, but obviously that's another potential source. Battery was replaced less than a year ago.

No car stereo/audio in there right now.

Edit:
Look at the scale differences. I know my tps was jittering mostly between 0.98-0.99V at CT. The scale you have of mine is 0.8-1.7V. Your scale is 0-5.3V, so the graph will hide noise, being 5 times wider.

Red herring?
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 22, 2019, 01:09:30 AM
Got my new BE version working, Not sure yet on how to mess with the scaling on this newer software, but I got this close. With A 0~5 scale, my TPS graph also looks clean.

(http://masejoer.com/Images/Thunderbird/Engine/MotorTroubleshooting/TPS-Graph.png)

Not sure this is any problem area to look into.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 22, 2019, 01:16:50 AM
Can I see how your spark timing looks at idle? I would think the computer may mess with fuel and spark timing to aim for closed loop, but perhaps mine is swinging more than it should on the timing?

 I also would think the computer wouldn't know that SPOUT disconnect is happening, and continue to try to adjust spark and fuel, making the engine run rougher - pulling SPOUT may not be enough of a test to smooth out the idling motor.

Locking timing via tune would be smarter, but may only work okay in open loop.

(http://masejoer.com/Images/Thunderbird/Engine/MotorTroubleshooting/Spark-graph.png)


Valleys and peaks of 16-25 degrees.

Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 22, 2019, 01:43:37 AM
Oh look, a thread from me 10 years and 15 days ago trying to solve this issue: https://www.eectuning.org/forums/viewtopic.php?t=15381

Back then:
"The basics are a 306 with gt40 intake, gt40p heads, ho cam, 2.5" exhaust, still stock 60mm TB and 55mm mass air sensor with panel air filter, 19lb injectors, A9P ecu, distributor at 10 degrees."

I always google issues and stumble across my own threads from years long past  :frown:
Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 22, 2019, 07:58:48 AM
You're right, I didn't even notice the scale difference I've compared the same PIDS on a lot of datalogs and its never done that to me thats weird. After work I'll find one with a good spark log and mess with the scaling of mine to see how dirty it comes out just out of curiosity.
Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 22, 2019, 08:30:52 PM
Ok so long story short I don't currently have any datalogs of idle with spark in it somehow. I have a lot of driving but not enough at idle to give any definitive result, although what I see in your log looks strange. As of right now my car is down, didn't notice my oil line to the turbo slid over against my manifold ended up burning a hole in it, talk about a mess. I just got the new line today should have it running this weekend and I'll get some logs of idle with spark. I did change the scaling of my TPS log and I don't see near as much noise also strange.  It could just be your USB cable and we are chasing ghosts. Do you happen to have any ferrite beads to put on it? I know mine came with them but I never had to put them on.

 
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 22, 2019, 09:08:58 PM
My USB cable is the supplied replacement with ferrite, which Moates sent after the initial release cables performed poorly.

Don't think that's it.

cgrey8 over at eectuning is thinking I should take a look at the actual timing events of the cam. Well alluding to it. I still think a stock cam, crank, and timing set should be a drop-in-affair without a degree wheel, but retarded timing would help explain my idle/low load issue.
Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 22, 2019, 09:26:45 PM
Well if its not the cable its either a strange issue or just my imagination but I have yet to see that kind of electrical interference out of one of these but it may be normal. I've had GMs at work that had so much noise you would think they were possessed, wipers going at random times, flashers randomly going off, fun to diagnose but like I said usually when I removed the random aftermarket stuff it would clean up the CAN signal and everything would go back to normal.


Is he referring to your timing table?  How would you check actual timing events of the cam?

Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 22, 2019, 09:39:47 PM
Sitting here thinking about it I remember a few years back I had a somewhat similar issue could not for the life of me get my idle to be steady but also on accel my tach needle would randomly jump all over, ended up playing the swap parts game until my cap finally fixed it, I keep a spare distributor with cap and rotor in my trunk now I've gone though 3-4 distributors and countless tfi modules the msd pro billet I have now has lasted the longest surprisingly enough.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 22, 2019, 10:08:31 PM
Yeah, the EDIS-8 conversion would allow me to ditch the distributor and TFI altogether.

Still trying to get a stock crank pulley for the project, for less than $50.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 23, 2019, 09:52:24 PM
Someone today suggested that if I'm pulling the intake off to degree the cam, I should temporarily convert to carb to see if the issue persists. Seems like a reasonable plan, if the parts can be found cheaply enough.

Anyone know of the cheapest options to try such a thing? Would need the intake and carb obviously, and could just use a pump to pump from a gas can. igniton box. Sounds like I should have access to everything to test this, except the 4 barrel intake.

Really curious if the idle would smooth out by ditching all of the electronics, and this could potentially be a huge diagnostic test.
Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 23, 2019, 10:58:23 PM
You have a stock cam in it right? Personally never had an issue but I also know all cams are different from one another. Is it possible yours is different enough to cause an issue, maybe but seems unlikely. Youre right though putting a degree wheel on it is the only way to know for sure but seems like a long shot to me. I personally would start with different plugs cap and rotor the maintenance stuff that has to be done eventually anyway. Cant say I've ever had a set of plugs last me more than a year even when I was N/A, now days I go through a set of ngk 5673-7 in about 3 months at most.  I would also try and set base idle by unplugging the battery and clearing KAM unplugging the IAC reconnect battery starting it and adjusting the throttle plate until it idles where I want then shut it off and plug the IAC back in start it and let it run for a while sometimes Ive had to do it a few times after replacing my throttle body to get idle back to normal. You said it acts up at 2000 rpm right? Like its misfiring?
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 24, 2019, 12:01:11 AM
You have a stock cam in it right? Personally never had an issue but I also know all cams are different from one another. Is it possible yours is different enough to cause an issue, maybe but seems unlikely. Youre right though putting a degree wheel on it is the only way to know for sure but seems like a long shot to me. I personally would start with different plugs cap and rotor the maintenance stuff that has to be done eventually anyway. Cant say I've ever had a set of plugs last me more than a year even when I was N/A, now days I go through a set of ngk 5673-7 in about 3 months at most.  I would also try and set base idle by unplugging the battery and clearing KAM unplugging the IAC reconnect battery starting it and adjusting the throttle plate until it idles where I want then shut it off and plug the IAC back in start it and let it run for a while sometimes Ive had to do it a few times after replacing my throttle body to get idle back to normal. You said it acts up at 2000 rpm right? Like its misfiring?

The cam that came out of a factory '89 Mustang longblock, yes. Originally had that with the topend from a '93 Cobra, and this A9P. I've been through various engine builds since then, with at least 3 plug wire sets, maybe 4 or 5 sets of plugs across the heads, 5 injector sets (three different 19lb sets, a 24lb, and a 30lb), 3 full distributors, 2 MAF sensors, 3 IAC valves, 3-4 EGR valves, 3-4 alternators, 3 batteries, a few new replacement engine and coolant temperature sensors, and who knows what else.

Kinda wish I just had an aluminum DART 351 block instead, machined from scratch and internally balanced...a fresh build.

I'll have to get a new parked video recording when I have some daylight.

On another note, my switching 5v regulator is arriving soon and I'll finally get the cluster's mechanical regulator replaced. Those three gauges have also annoyed me forever.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 24, 2019, 05:49:25 PM
I'm going to agree with Outsidedog. I highly doubt it's the cam timing. Every stock Ford 302 on the assembly line just had the HO cam installed dot to dot and they ran fine. It has to be some crazy electrical issue. Was the cars harness ever "worked on" before you bought it?
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 24, 2019, 09:19:16 PM
Car has been in the family since 1991. It ran perfectly smooth with the stock powertrain, up until I swapped it out with the completely new motor. Has never idled correctly since.
Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 24, 2019, 10:28:05 PM
Still going to get you that datalog of my spark at idle this weekend. But until then I have more questions, what AFR are you shooting for at idle? are you hitting it? and when was the last time you calibrated your wideband sensor?

Whats your fuel pressure at idle and what does it change to when you pull the vacuum line off the regulator?


So you have an A9P running on a 4r70w. Which controller are you using to control the trans?

Sorry for all the questions there's just such a wide range of things that can affect idle quality and trying to give you any sort of good idea without being there is difficult.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 25, 2019, 12:14:38 AM
Still going to get you that datalog of my spark at idle this weekend. But until then I have more questions, what AFR are you shooting for at idle? are you hitting it? and when was the last time you calibrated your wideband sensor?

Whats your fuel pressure at idle and what does it change to when you pull the vacuum line off the regulator?


So you have an A9P running on a 4r70w. Which controller are you using to control the trans?

Sorry for all the questions there's just such a wide range of things that can affect idle quality and trying to give you any sort of good idea without being there is difficult.

The AFRs are simply switching around lambda, I run 92 octane "up to e10/whatever they have in the pump" sometimes, sometimes 92 octane e0. I have mostly the 92-octane from a chevron a few blocks away in there right now. Of course it'shiznitting lambda if the narrowband o2s are switching.

I haven't touched the wideband in years, but I do have a second new gauge-less one to install here soon in the passenger side. I've had an old aem thing in there that requires the gauge, and outputs the signal line from the gauge. Driver side has the Innovate LC-2 screwed ion.

FP was mentioned earlier - it's 33psi with 16in of vacuum, 39psi with vacuum detached. I'm going to play with some random tune settings this weekend to see if ANYTHING gets the idle any smoother.

4t70w is running from the original Baumannator TCS. Don't remember if this trans went in with the motor in the mid 2000's, or if I briefly ran the aod. I've had the 4r in there since before the Quarterhorse though, and likely before I ran a TwEECer.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 25, 2019, 12:45:11 PM
Car has been in the family since 1991. It ran perfectly smooth with the stock powertrain, up until I swapped it out with the completely new motor. Has never idled correctly since.

I guess it could be mechanical (cam shaft) but it just doesn't seem likely. Just swapping engines shouldn't screw with the electronics, unless some wiring got pinched/cut in the process. It just seems light a giant PITA to degree the cam and put a carb intake on for testing if it doesn't solve the problem.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 25, 2019, 01:09:55 PM
Agreed on the pita, but carb is easy if you already have the intake pulled. Just re-use the old gaskets with rtv for the test, and new gaskets when reinstalling the efi intake. Degreeing the cam, I'd just advance it while in there already. I'd completely swap the cam if I wasn't worried about ptv - don't want to pull the heads. The motor has a ton of ptv clearance right now though - lots of clay thickness when I tested it during the head install.
Title: Re: Troubleshooting persistent misfire
Post by: thunderjet302 on October 25, 2019, 01:59:40 PM
What pistons are in the engine? If you've got the HO style pistons and TW heads you probably have miles of clearance with most off the shelf cams. Heck a local guy has an 86 Thunderbird he put a TW top end kit on. With the stock 86 Thunderbird flat top pistons (engine and whole car had 8600 miles on it when he did the swap) and a TF Stage 1 cam he had miles of clearance.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 25, 2019, 02:52:08 PM
Yeah, they're stock-like. TRW-L2305F30 pistons.

Block was 0-decked and TW170 heads were milled .030 to get 54c chambers. With those and the HO cam, there was loads of clearance when I checked. The clay looked to have almost as much as 1/2 inch - I didn't measure exactly as it was simply thick.

I am happy with the HO cam, if I could get the shortblock to run smoother at idle. Don't care about getting every last bit of power from the motor (even +30hp), it already moves fine with the parts it has. But if I were building a new shortblock today and knew I wouldn't have ptv clearance (clay), of course I'd try a different/newer style cam that's a bit more aggressive. I'd also run a completely different longblock, and wouldn't be cheap. Then I'd probably still have idle issues and hate driving the car.
Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 25, 2019, 09:35:38 PM
Weird I swear I looked through all the posts and didnt see a thing about fuel pressure.
Maybe try tuning it, you have all the equipment, force OL and recalibrate the afr sensor and adjust your MAF transfer until your open loop fuel table and AFR gauge agree with each other after the engine is warm. Maybe its just not happy because its getting more airflow than its expecting because you have a 306 with tw heads and a gt40 ported intake running on a stock tune. I mean im sure people have done it, but every single engine is different from each other not one tunes the same as the other. You could also tune the Idle but thats more difficult to walk through without being there and seeing the data, the link I sent earlier from efidynotuning is probably the best info on tuning idle Ive found anywhere.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 25, 2019, 11:03:18 PM
Yeah, I want to throw fuel at it again. When I did this weeks ago, it didn't clear anything up, but I was also on the dying coil. Need to re-do some tests.

Install second LC-2 wideband in passenger bank and hook up to DataQ, setup in BE, run engine until CL and make any adjustment if necessary to get wideband map closer, disable CL and mess with either injector values or MAF depending on which settings look like they'll be the correct correction, richen mixture a point and see if anything smooths out. Mess with timing and see if anything smooths out. Run car without alternator to see how it is on a fixed DC Voltage from the battery. Run second EEC-IV ground from battery to EEC.

These are some of the things that I'd like to perform and (re)test tomorrow. Simple tests out of the way.

The stock tune reading the stock MAF should be pretty dead-on though, with the factory tune. Stock airbox. Airflow metering should be accurate between it or the PMAS/Pro-M MAF.
Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 26, 2019, 11:29:05 AM
Airfliow may be close but without an accurate wideband reading we wont know you'd be tuning in the dark. How are you going to set up the wideband in BE I have mine hooked to the EGR output and adjusted the transfer function accordingly. But you're still running an EGR right? I run an innovate LC-2 w/gauge haven't used the dataQ yet. Disconnecting the alternator is a good idea maybe see if your datalog signal cleans up still a long shot but worth a look.
Title: Re: Troubleshooting persistent misfire
Post by: Masejoer on October 26, 2019, 12:11:50 PM
The Wideband(s) are on a DataQ. I have the EGR blocked off right now, but also have never used it for o2 input. Hardwired via buttstuffog lines in DataQ only.

I just need to look at the spec sheet and reset the wideband map to factory range, check again, and adjust as needed to get close to the switching from the narrowbands (a bit above and below lambda of 1).
Title: Re: Troubleshooting persistent misfire
Post by: Outsidedog on October 26, 2019, 07:06:10 PM
(http://Screenshot (10).png)

Heres my spark at idle, Its brief because I have more oil to clean up turns out. Also while you're tuning bump your base idle up 100 rpm and see if it smooths out at all.


Just so you know my tune is always open loop. I did that so I can lock the fuel and timing in and don't have to worry about the computer trying to adjust when I'm about to hit the nitrous. I always know what spark and fuel I should be at for any given Load.