eyal928

My 1988 928 is stalling below 1200 rpm. Otherwise the car runs perfectly. My mechanic has checked both brains, changed the crank trigger, changed all the hoses under the manifold, changed the throttle switch, changed the injectors, changed the crank shaft and he told me it is not the temp 2 sensor or anything easy. Posche 928 Intl is telling him the car needs a new engine but he says no way. Has anyone dealt with this type of issue or does anyone have any leads to help us. Fortunately my mechanic is an honest guy and he is trying to help me even though he spent an immeasurable amount of time working on this. He suspects it may be the shielding on the crank trigger harness and that is what he is checking next. Any thoughts would be greatly appreciated. Thanks for your time.

86'928S MeteorGrey

You can check your ICV for proper function, and the harness that connects it.


Is your car an automatic?
and if so,
Have you checked for thrust bearing failure? (TBF)
(forward/rearward movement of the flywheel)
Mount an indicator and pry the flywheel forward and aft. If you get more than .017" (and that is extreme) then the motor is dead.

dfrhodes

what does 'checked both brains' mean exactly? did he swap them out with known good ones?

is the problem intermittent? or does he have the idle jacked up to keep it running?

eyal928

The problem is intermittant, the car will just stall when idling at low rpm. It started very suddenly one day when I was driving and it started happening each time I stopped while driving. My car is automatic yes. I am not sure what my mechanic means when he says he checked both brains but I know he sent the computer to be checked and it checked out ok. Any other suggestions please let me know so I can pass the info along to him. He is a very bright mechanic but this issue has stumped him for 3 weeks.

fraggle

Only hot or all the time?

eyal928

All the time. My mechanic has tried a million different things and he tells me that the car will stall whenever idling at 1200 or lower.

daveo90s4

What does 'changed the crankshaft' mean - did he really change the crank shaft?

Have you checked the crank shaft end float? I think you need to (hopefully) eliminate thrust bearing failure as a priority.

Good luck

SeanR

It's either the TPS (throttle position sensor), the ISV (Idle stabilizer valve) or you have a voltage drop at the ignition system. This could be coils, coil wires, bad grounds etc. Could be a number of things but those are the major things I'd check first.

SeanR

Oops, forgot one. Bad MAF could do this.

eyal928

We switched out the MAF with one in my other 1988 928 and that was not it. My mechanic does not think the engine needs to be replaced even though that is what some experts are calling for. Any other ideas?

SeanR

Hmm, let's not go that far, tell me about the post above that, has any of it been taken care of?

86'928S MeteorGrey

I've chased these symptoms before...

I'd first take the 15 minutes and check the flexplate for pre-load... Then check the flywheel fore/aft play. It will save you a lot of labor if it's the culprit, and it needs to be done anyway. The first time you pull the flexplate cover, you will need to drop the exhaust. When you put the cover back on, do not use the two bolts that cannot be removed with the exhaust in place. Next time it will be very simple to check.

GOOD LUCK.

Question. When the car is running and at speed, does it feel lower on power at all? Any hesitation with acceleration?

daveo90s4

eyal928, can you tell us the reason for some saying your engine needs to be replaced? And have you checked and eliminated such a reason?

eyal928

No the engine is running great, I will ask my mechanic why someone recommended a new engine. He does not believe it is the engine. I should have taped my conversation with my mechanic because he has tried so many things. I will go over everything mentioned above with him, please let me know if you have any other suggestions. Much appreciated.

dfrhodes

very curious. I also have an 88' that randomly stalled the same as yours, but it turned out to be a bad LH. So if you are committed to solving this, somehow you need to drive it with real-time diags running to catch in the act - like with a shark tuner or theo's tool. Obviously you are either getting starved randomly by fuel/air, or ignition is failing for some random reason. the brain know if you can record it.

...or - you have an accessory/tranny momentarily seizing the engine (like the AC compressor kicking in???) that's a serious long shot though.

drastic action - pull the engine and run it on the stand until it fails?

IMHO there are still things you can do before committing to a new engine.

david