Mysterious engine stumble and cut out - mechanic can't fix

[redbaron]

I just bought a 91 2+2, beautiful body, etc, but the car didn't run right. I has a harsh hesitation on acceleration, but runs fine once you get going unless you lug it or try to rapidly accellerate. After being in a specialty shop for over a week, where they replaced every part they could think of temporarily, they determined that the car is not adjusting the timing properly on accelleration, and the plugs seem to foul a lot.

Also, the car will just cut-out on the freeway interemittantly, even going straight down the road with the cruise control on. Sometimes pumping the gas will restore power, but it just feels like the ignition was turned off. Last time, when I pulled to the side and restarted it, I held the pedal to the floor and the engine reved up and down in a predicatble sequence.. I started it again and it ran okay, but still the stumble.

According to the mechanic, they tested the ECU, cam sensor, TPS, oxygen sensors, maf sensor and all the fuel system components. They say this is not a common Z problem...

[NSR240sxe]

Congrats on the purchase and welcome to NICO!!! Sorry to hear about your problem and sorry I cant be of much help. Good luck though and I hope you can figure out what's wrong and get it fixed

[Outkast]

Have the PTU check, if the sub harness is cracked or damaged it'll do the problems you described. I say this cause my TT recently did the same thing and after I replaced the $450 dollar part it all stopped.

[evildky]

another vote for the PRU, it's on the front of the passanger side timing belt cover

[redbaron]

What is th PRU? Are you talking about that small module on the timing cover with connectors on each side of it?

[evildky]

sorry, typo, PTU and yeah thats it

[Outkast]

That would be it.

[nsrZ32]

As mentioned.....PTU is the most likely cause.

[DustinZ]

let me know I have one used if need be. [email protected]

DustinZ

[redbaron]

It wasn't the ignition module, the MAF, crank angle sensor, or a myriad of other new parts recently installed.

My one last thought is the TPS is out of adjustment, but I hear that is a real pain to calibrate.

I'm very very close to dumping this car now that its looking more and more like a nice money pit.... I have a boat and three Italian cars (that run well) for that

[evildky]

so you didn't try the PTU yet? also being an intermitant failure, it could be something as simple as a wire rubbing somewhere, in which case tracking it down will be rough

[Ill give u a head start]

i had a similar problem on my 91 tt that i wrecked about a year ago. It would stall sometimes on the freeway then all the sudden turn back on when i tapped the gas pedal. I had it checked out by a dealer and they said that all my fuel injectors had high resistance and they said something about the sub harness cant remember what.