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Topic: 84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed (Read 5386 times) previous topic - next topic

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #15 –
Does the exhaust smoke a little when you restart after it stalls? Having to open the throttle to restart sounds like it is flooded.
On the ECT, I should have told you to check the voltage between the two wires to make sure the signal return is not an open circuit. That is put the red meter lead on one wire and the black meter lead on the other wire.

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #16 –
When it does the hiccup, the 02 sensor voltage shoots up (0.7volts and above).....so it goes rich when it runs like . So then I go crank it, no start. So then you have to open the thottle to start it, and some of time it will shoot a flame up the TB when it fires.

I did put the leads between the sensor leads, the voltage was lower.....i want to say about low 7volts. When it was wire lead to battery....it was about 7.8volts.

I appreciate your help.
1984 T-Bird Elan 5.0 (sold)
1994 T-Bird LX 4.6
2009 Dodge Charger Daytona 341/400
2013 Camaro SS

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #17 –
Does it have a spout? If so take it out, sounds like your timing is jacked with backfiring out the TB.

Does this have the "brain box" on the fender? If so check that guy.
88 Turbocoupe: Coast High Performance 331 kit 28oz balance, Comp XE264HR14 cam, 58cc 185 afr heads, 1.7 roller rockers, Mass-Flo EFI (was POS to setup and their techline is a joke at best)
Full 1 5/8 primary equal length headers, 2 1/2 exhaust, Full manual reverse VB c4 and baked off clear coat "BECAUSE RACECAR"

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #18 –
No spout. It's EEC-III. Timing is not adjustable. Has a crank sensor that feeds the ignition module.

Yes it has the ignition module on the fender, even that was replaced.
1984 T-Bird Elan 5.0 (sold)
1994 T-Bird LX 4.6
2009 Dodge Charger Daytona 341/400
2013 Camaro SS

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #19 –
When it stalls, check to see if one of the injectors is dripping fuel, not sealing.
Try running with one injector unplugged then the other unplugged.

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #20 –
Funny that you said that....

I did that too last week....it runs but barely/rough on one injector at a time....and both sides seems the same roughness.
1984 T-Bird Elan 5.0 (sold)
1994 T-Bird LX 4.6
2009 Dodge Charger Daytona 341/400
2013 Camaro SS

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #21 –
Where is the pcm located and how do you get it out?

Can you remove the injectors with the TB on the car? What's the trick to remove the injector from the rail/TB?
1984 T-Bird Elan 5.0 (sold)
1994 T-Bird LX 4.6
2009 Dodge Charger Daytona 341/400
2013 Camaro SS

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #22 –
Quote from: Smkn600ctd;368097
Where is the pcm located and how do you get it out?
On the EEC IV the EEC is behind the passenger side kick panel.

Quote
Can you remove the injectors with the TB on the car? What's the trick to remove the injector from the rail/TB?

Never done it, but pretty sure you have remove TB.

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #23 –
Quote from: Smkn600ctd;367940

It only does its BS once it warm, and only after about 2 min after it restarts.


Sounds to me like it's going nuts when it goes to closed loop, just for grins disconnect the O2 sensor and see if that changes anything... At 27 years old the computer may well have a issue, I had bad capacitors in my '93 Lightning PCM that made it go nuts(which I replaced and it's fixed)... Still I would not replace the ECM till all the other possibilities were covered...

One more thing, you mentioned the idle dropped with the A/C on, sounds like the ECM isn't sending a signal to the idle motor to increase speed...

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #24 –
That's exactly my thought that is going on. The question is why it's going nuts.

The car doesn't have a idle motor, just this vacuum kicker/dashpot. When it starts going nuts, you see the kicker and the fast idle pulloff (their are both controlled by the same solenoid and same line) kick out and then back.

The only thing not replaced at this point is the crankshaft sensor and that's because it's a major undertaking (remove alt, smog pump, it's bracket and everything else associated with it)

There is 83 eec3 car at the pick a part, so a PCM would be cheap. But how do I get it out/location?
1984 T-Bird Elan 5.0 (sold)
1994 T-Bird LX 4.6
2009 Dodge Charger Daytona 341/400
2013 Camaro SS

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #25 –
The ECM should be in the passenger side kick panel(the IV are there)... Probably will be a support bracket that has to be loosened, also the electrical connector will have to be removed before it will slide out...

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #26 –
Swapped in a different ECM...........same thing.

Was playing around with the ECT, and it looks likes runs better with it unplugged. Sometimes it will start with it unplugged, other times it has to be plugged in to start. If its running and you unplug the ECT, it will sometimes die or I can plug it right back in and unplug it....then it will run.

Watching the 02, it running at .1-.2v, then will hiccup and it goes to .7-.9v at idle.

No wonder why the techs used to call these cars "run-away cars".....
1984 T-Bird Elan 5.0 (sold)
1994 T-Bird LX 4.6
2009 Dodge Charger Daytona 341/400
2013 Camaro SS

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #27 –
IT PASSED!!!!!!!

The numbers were flat out awesome....flew right through the dyno smog test. 37 HC 0.01% CO 277 NoX

Then while idling....it died. Had not died in three days, just the hiccup and lowering idle. While I was there talked to a old school ford mechanic who thought it could be fuel pressure regulator maybe malfuctioning.

So half the saga is done.....
1984 T-Bird Elan 5.0 (sold)
1994 T-Bird LX 4.6
2009 Dodge Charger Daytona 341/400
2013 Camaro SS

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #28 –
So I spent all day f-ing with this car.

Changed the fuel filter.....no better. Ohm checked each of the solenoids.....all in spec. I double checked the ect and act. Swapped map sensors back and forth. Egr position sensors swapped for old and back to new.

I give up.
1984 T-Bird Elan 5.0 (sold)
1994 T-Bird LX 4.6
2009 Dodge Charger Daytona 341/400
2013 Camaro SS

84 5.0 EEC-III Engine dies at idle randomly, rough idle at times, runs great at speed

Reply #29 –
change the crank sensor if its one of the last things left, if its bad it would explain why the motor loads up with fuel, the spark cuts out and loads the exhaust - o2 spike at stall