Faulty coil? run + park + restart = lumpy idle

[PaulPDX]

I've noticed a few times that my 91 Talon AWD doesn't want to idle (restart) if it has been running for a while. Like run for a couple of hours, park for a few minutes, and then restart.

The problem seems to be intermittent. Most of the time it fires right back up just fine. However, today while I was running errands (lots of short trips with 30 min breaks in between) it did not want to idle at all after the last errand stop. Almost felt like only some of the cylinders were firing. Lots of vibration and after about five seconds or so the motor just dies completely. I started it again, same result. The third time, it started out the same, but this time I reved it while it was doing the lumpy idle thing... once the rpm's got up to 1500 rpm or so it sounded and felt like all of the cylinders were finally going. Close to normal, but still a little rough.

I had a new 2001 Isuzu Vehicross that did the same thing.

What could be the problem? Is the engine bay heat causing the ignition system to go haywire? or is it something simple like a clogged fuel filter?

I have no idea when the filter was changed, or if it ever got changed. Bought the car a few months ago with 83k miles.

 

[Black_Stalon]

I had same problem, gradually got worse over time, ended up the coil pack had fried.

 

[PaulPDX]

Replace with stock or aftermarket? if so which one?

 

[dsmturboawd]

i had the same problem. i swapped ecus and the problem was gone.

good luck.

 

[PaulPDX]

Originally posted by Black_Stalon
I had same problem, gradually got worse over time, ended up the coil pack had fried.

Did you replace just the pack or the power transistor as well?

 

[Black_Stalon]

replaced the coil pack, and the wires cuz 2 of them fried along with it.

 

[PaulPDX]

UPDATE

I think I have a better idea on the problem and under what circumstances it occurs.

The sputter / stall on start turns out has nothing to do with engine bay heat or drive time. It has to do with how the car is parked.

I found out that this happens when the car is parked on uneven ground where the passenger side is lower than the driverside and the rear end is slightly lower than the front.

What could be the cause? I know it's not the fuel filter... that was replaced a month ago.

And... I know it's not the ECU because that was replaced shortly before the previous owner sold the car to the dealer where I bought it from in October.