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Topic: Strong engine stumble (Read 1846 times) previous topic - next topic

Strong engine stumble

Driving normally at highway speeds, this past week I have picked up a strong stumble. So much so, it feels like the fuel pump or ignition is shut off.

Being as I picked up a cheap fuel pump from Craigslist, I assumed that was the cause. Hooked up the gauge and I have a perfect steady 42 psi with vac line off and about 34 with it on. Preassure rises with throttle, so everything seems to check out.

I run codes, I get a 91 (lean drivers side) 34 (get out of range) and a air injection code.

I pulled the egr off since its really easy to get to, and its stuck and has a ton of black gunk. Cleaned it up, and minimal preassure moves it in and out. Looked at the smog pump, and I have a missing hose clamp. Whoops, wonder how long its been like that. Hooked that back up.

Unfortunately, engine was too hot to do the o2 sensor, so I let it be for now.

After messing with the egr and smog pump, I ran codes again. They still show up, havent cleared them yet. I then ran an engine cylinder ballance test. The motor isnt running smooth, but I had just ran codes and figured why not.

Got a 90 the first time and a number 5 the second.

Now obviously the o2 is going to affect the car running well and that is in the works for tomorrow. Ive noticed a drop in gas mileage too, so if thats all it is it would make me pretty happy.

So the plan right now is to swap that o2 and see where I am at tomorrow.  Ill probably pull the number 5 plug while I am there and make sure it looks okay, but the plugs aren't that old.

The real question here, I've lucked out pretty good on o2 sensors. The only time ive really had to replace them was for emissions. I never really noticed a big difference in how the car ran. Can a bad o2 cause my bad stumble?
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Re: Strong engine stumble

Reply #1
Usually O2 sensor being bad wouldn't cause the stumble you are describing.
How fast is fast?

Re: Strong engine stumble

Reply #2
I didn't think it would. I wouldn't mind a gas mileage increase that I've recently noticed a drop on.

Guess ill swap in my spare dizzy/tfi setup this weekend and see if it clears anything up.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Re: Strong engine stumble

Reply #3
Well, I habe an update. I dont think its the tfi or the o2 sensor.

While driving today a spark plug blew out. It wasn't loose, the center electrode was spinning and moving in and out of the outside body of the spark plug.  This is the same side I had the o2 code on, so I think its all just bad plugs.

I didnt have any tools, but coasted into autozone, bought a $1.99 autolite and it is running much better. Autozone loaned me a socket and had it done in 30 second. Guess I'm gonna do the rest this weekend.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Re: Strong engine stumble

Reply #4
So I changed out all the spark plugs. One or two were pretty used up and way out of gap but non seemed to be super bad.

After that the car seemed to run much better so I left it alone. Of course it started the random sputtering again. This time I put the fuel pressure  on the window. Couldn't get it to dip or do anything funny.

Ran codes again, smog pump (82) which is bypassed. And get came back (34) so I am gonna mess with that next weekend. Ran another engine cylider ballance test and it passed, no more o2 code.

Since its still been stumbling, I pulled the dizzy/tfi out of another car. Cap looked pretty good and so did the rotor button. Cars running pretty good, gonna try to drive it again tomorrow but I couldn't get it to do anything bad.

I'm not convinced its the tfi/or pip, but it should rule that out if I have any more problems.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Re: Strong engine stumble

Reply #5
I had this happen on the Coupe and battled it for over a year only to find out the bushing in the distributor was worn out and under acceleration it was screwing up the timing and spark.  Bought a remanufactured distributor and car ran really well after that.

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Re: Strong engine stumble

Reply #6
Well, I guess it was the distributor or tfi.

I pulled the spare out of my engine (been sitting since probably 2007 and dropped it in. Car feels a bit lazy, might have gotten the timing a bit off, but it hasn't stumbled once since.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Re: Strong engine stumble

Reply #7
Well, 4 or 5 days later and the stimble is back. Not quite as bad, but very erratic and intermittent when it does happen.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Re: Strong engine stumble

Reply #8
Ignition coil? Stuck valve? Had a similar issue on my 95. Never got around to really fixing the stuck valve as it would free itself back up after the car warmed up a bit, but the ignition coils were garbage. I know 4.6l =/= 5.0 but its a thought.
'88 Turbocoupe 5 speed.

Re: Strong engine stumble

Reply #9
Well I've pretty much verified fuel is good as well as the computer and I have already traded out the tfi/pip. I have had a bad coil once. It was arching out to the fender. Honestly the car still ran good while it was doing that. Just happened to see it when I was topping off washer fluid late at night.

I'm down to wiring or fiddly things. Working 6 days a week, 10 hrs a day 3 hours from home is catching up to me.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Re: Strong engine stumble

Reply #10
So I went out to the car and the battery was dead. I hooked up the jump box and didn't even try to start. Got out to cables and something was visibly on fire under the intake manifold near the rear bell housing.

Shut off the jump box and pulled the cable. I was able to blow out the visible flames. But I am at a complete loss. I've never had a car catch on fire, and the only wiring I could see In the area was the o2 sensor harness. Fuseable links don't appear to be melted. I am not going to have a chance to mess with it until next weekend. Gotta be in bed by 8 and up by 4:30 in the morning for work
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Re: Strong engine stumble

Reply #11
sounds strangely similar to what I was experiencing recently. was trying to jump start the car on a totally dead battery and would see smoke from the firewall-ish area. mind you, this was a 2.3t, so it may not be an engine thing or could be totally unrelated. I actually ended up replacing the vehicle's battery, pulling the whole driver's side harness back to check for shorts and found nothing but a few portions of copper wire from the fusible links and some grody looking connections at the anti-theft relay (you know the one thats connected to the vacuum tree, right by the booster?) cleaned all that up real nice, reloomed the harness and made quintuple sure everything was plugged in properly. might be a good time to check all the grounds and replace any cruddy looking terminals if you can't find anything else to cause the issue.

Hope this helps, but I look forward to seeing what you come up with.
'88 Turbocoupe 5 speed.

Re: Strong engine stumble

Reply #12
O2 harness is melted. Gonna try to pull it now.

Is there no fuse or fuseable link for o2 sensors on an 86?
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Re: Strong engine stumble

Reply #13
Unplugged the o2 harness because I forgot how much of pain it is to get to. Hooked up the jump box and it no longer gives me an error and the car starts right up.

Soent about 30 minutes pulled the connectors off the o2's. One connector is melted at the o2, so i need to either replace the o2 or repin it with another and haven't gotten the other side fished out quite yet.

Started it up jist for fun. Idles a bit off but seems to have fixed the fire and hopefully my intermittent stumble and battery issues.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Re: Strong engine stumble

Reply #14
Seems to be fixed. I left it dead for a week so I am gonna test drive it and make sure the battery is good still.

Hopefully its good enough to drive to work tomorrow.

Seems to be running better. I'm hoping somehow this had to do with my strong stumble.

Pretty sure the wires were shorted out between the heated o2 wire and who know what that did to the eec.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com