Skip to main content
Topic: 88 Bird intermittent engine shut down***SOLVED (Read 986 times) previous topic - next topic

Re: 88 Bird intermittent engine shut down

Reply #75
tach signal wire has no continuity to chassis
tach signal wire has no continuity to any fused load

thinking on what to check next.


for the record...
when the event happens each and every time we demand rpm,, the engine cuts out and tries to recover.
the problem is more and more pronounced if the engine is hot.
when the engine is at driving temps,, it will fail to start at all.

Could this be a MAF problem....
i have spark
i have fuel
i have alternator
i have start up conditions easy if engine is not really super hot
car idles good
it falls on its face when we add pedal,, so i am thinking one thing that remains is airflow and the parts associated to that.

Re: 88 Bird intermittent engine shut down

Reply #76
with the ign sw , eec & tfi unhooked along with battery unhooked, the TFI wires below have continuity with each other.
rd/lg
r/lb
dg/y
r/lg  Hot in start & Run to EEC power relay coil..bottom of coil to ground (Chassis metal)
r/lb Hot in start to starter relay coil...bottom of coil to ground (Chassis metal)
dg/y Tach wire to tach electronic circuit in cluster. electronic circuit has a ground (Chassis metal)

They are all tied together through the chassis metal. That's why you have continuity between them.



Re: 88 Bird intermittent engine shut down

Reply #77
ok,,
we are using a heat gun on the mass air sensor with a bone cold motor to simulate the car is hotter.
we are trying to see if we can make the car fail early by heating the maff housing .

we do know that when the car gets hot, the problem is more pronounced.


Re: 88 Bird intermittent engine shut down

Reply #78
we might be on to something.
we heated the mass air and the problem remained.

we unplugged the mass air sensor and the engine should have died but it did not
we even added gas and the car tried to fit it a bit but it took the rpm we gave it and held.
we even turned on the headlamps.

normally when we give it rpm, to say 3k,, the engine sorta feels like it ramps up then rolls down to a dead stall.
we also get the same symptoms by simply picking headlamps. and some minor rpm.

so....
what say you all?

is there a possible condition that the maf could fail yet not throw a code?

 

Re: 88 Bird intermittent engine shut down

Reply #79
i never knew how to,, but this guy did a decent job of dialing in the details.
https://www.youtube.com/watch?v=p0ocaDmcAIM

we will test our maf tomorrow

Re: 88 Bird intermittent engine shut down

Reply #80
we followed some various ways to monitor the mass air flow sensor....
one way was to side tap a wire the computer is using to monitor the voltage. 

maf unplugged on wire harness end  , KOEO unless otherwise noted below,, here are the results
pin A = 12v
pin b  = continuity to chassis
pin c  = no continuity to chassis ( with engine running,, at idle, volts= .9v,, smoothly increased to 2vdc at wot),, somehow we were able to get some higher rpms to get this test.
Pin D= no continiuity to chassis,

It appears our maf is good.

Re: 88 Bird intermittent engine shut down

Reply #81
engine and EEC grounded properly?
'84 and '87 Mustangs
'98 Explorer 5.0
'06 Lexus
'06 Explorer EB 4.6

Re: 88 Bird intermittent engine shut down

Reply #82
************** we gained info...................

we got the engine hot and now even without a belt we can make the car fail.
so.........the idea of taking the belt off has no relevance.

Also,,, 
we gained another piece of info...
after the car did get warm,,, we lost all tack signal to the coil...
which means we lost spark.
the computer controls the ground ref to the coil,,, and apparently after the engine gets warm enough,, the computer will shut down spark.




Re: 88 Bird intermittent engine shut down

Reply #84
beau,,
yes good ground


we gained another piece of info...
after the car did get warm,,, we lost all tack signal to the coil (ground to the coil)...
which means we lost spark.
when the car fails,, while hot,, we try to restart and it wont,, and the reason why is there is no spark.

the computer controls the ground ref to the coil,,, and apparently after the engine gets warm enough,, the computer will shut down spark.

Re: 88 Bird intermittent engine shut down

Reply #85
so,,,
its either the TFI or the computer..........

the web is saying that its getting hard to get a new TFI that is good out of the box.....

a few weeks ago when this issue was more tolerable and manageable, we decided to swap the dizzy for new from advance.  the issue was getting worse and worse.  we took the new dizzy from  advance a few weeks later and traded it in for new...

so this car is on 3 dizzy's since feb.

 


Re: 88 Bird intermittent engine shut down

Reply #86
so,, im confused..
im watching a vid on testing a tfi in a ford 5.0...

they is testing each side of the coil.. he is saying a few things that contradict what i thought.

he shows a test light to the batter side of the coil to chassis then he cranks,, light stays fairly solid,, no blinking etc...normal.

he show the other side of the primary with test light to gnd... like sorta blinks.... normal.

yet he says ***********the reason why my car is not actually starting is because there is no computer plugged in.!!!!!!!!!!!!!!!!

I was under the impression the eec supplied the pulsed reference ground to the coil.. he implies that the TFI does that job.

on this wire ,, in our cars , it ties to pin  4 on the eec and consists of a 22kohm resistor in series with it.

I am basing my not having spark after the engine  is really warmed up and hot to the computer failing to provide a ground.

??????????????

Re: 88 Bird intermittent engine shut down

Reply #87
OK,,
tomorrow i will make sure everything is connected up like normal.

if i disconnect the spout connector and the car runs fine,,, then that tells me something....

it means that ....

A- the computer is a probable fault when the spout is in
B- the reasons for the computer may be the computer itself or a low voltage input to the eec.
~~~ apparently if the input voltage from the eec power relay is sort of low,, and if the spout is plugged in you will have conditions of intermttant or no or low spark.
This also meants it misguides troubleshooting and wastes time.
C-wiring  to or out of the eec power relay load side contacts is either experiencing high resistances or high resistances as a result of either load or heat.

to answer my own earlier question----- NO the computer does not manage the ground to the coil to deliver spark.  that is done primarily by the TFI.  the computer takes in a pip signal and sends it back to the tfi.

Re: 88 Bird intermittent engine shut down

Reply #88
ran engine at idle till it got hot,,, got the motor to the point that stepping on the gas makes it cut out.

disconnected the spout connect and the car still did not start.

if the car started then that would mean a bad eec or power feed to the eec

it seems to be a TFI

Re: 88 Bird intermittent engine shut down

Reply #89
replaced TFI,,, with no codes pointing to anything spark, lean , rich , pip etc,,,,, the TFI gave us continuous good running performance at idle for over an hour. 

Step on the gas and all is well.

turn on the headlamps and step on the gas...... car starts to kick back and buck.

turn of headlamps
undo spout conn
restart car
all is well
add headlamps and car begins to buck and kick back on us.
turn off car and think
................................................................... 
remove headlamp sw
start car with spout plugged in
paperclip jumper the headlamps to "ON"
car buck and kicks back on us... so............

I conclude thus far that the action of adding headlamps may perhaps be the cause of what i believe is the idea that this car is "EATING" TFI's.  We are on our 3rd dizzy since march... meaning we either A- thought the box store dizzy was a out of the box failure or b- the car ate the ign module fairly quickly.

I believe we have rolled the clock back to about two weeks ago when the symptom was  "car cuts out and dies randomly" although in my post 1 i implied early on that the addition of headlamps and the visual of loss of Tach seemed to be the only common denominators.

so... we are doing a test drive today with no headlamps to confirm that if no lamps are picked, we will find out if the car runs as it should.  IF YES- we move over to looking at the possibility of the headlamps and the factory equipped auto-lamp ckts  are not conflicting each other.

I do have some one piece f interesting news............
while the car was running during its 1 1/2 hour time frame,, mason took amp clamp readings on either side of the battery.
on the hot cable input he had 3amps, on the ground side he had 8 amps.
i find this odd  personally.  its as though there could be another active circuit that is back feeding chassis ground.
i told mason to install a blocking diode between battery neg post and battery negative ground cable in the correct direction so that the battery can see chassis but anything on chassis cant see battery neg.,,, that might not be a good idea but i am trying to see if we can find out whats up with 8amps on the ground side.

the alt total amps during the above i describe was about 14amps.