1989 Carrera "dieseling" Problem

[xxultramistersi]

Just checking to see if anyone has seen this problem.
I have a 1989 carrera 3.2 that has had moderate engine work done to it, but nothing too serious. Recently, the car has been "dieseling" upon shut off. After I turn the ignition off, the car seems to try and start itself up again. There is no power but the engine keeps sputtering and attempting to turn itself over. It usually does this for a few seconds then shuts off. However, sometimes it keeps going, and since there is no more power to shut off I just stalled it to stop the engine from turning. Start up after these occurrences is also problematic, and it sometimes takes 2 tries to get the car running. Once it is running it runs great. Any thoughts?
Thanks,
Andrew

[db_cooper]

Try a new DME relay..the one under the driver's seat. You should have a spare DME relay as a spare.

Sounds like the fuel/ignition is staying "live" with the key off..that would be a DME relay problem.

To "diesel" with the ignition off (assuming a hot spot in the combustion chambers) the engine need fuel, which it should not get with the DME system off.

$30 from our host: 911-618-154-01-M252

[CCM911]

If it is not an electrical issue, I would run through some Techron(or the equivalent). There could be some deposits that are burniong upon shutoff.

Also, do you run the car hard? If not, you should.

For all we know, your car will merely need an "Italian Tuneup".

[redstrosekNic]

Dieseling can be horrible for any engine. Make sure you slowly let the clutch out when you're in gear as you turn the car off.

[lupin..the..3rd]

Originally Posted by redstrosekNic

Dieseling can be horrible for any engine.

... not a diesel engine.

[redstrosekNic]

Originally Posted by lupin..the..3rd

... not a diesel engine.

Lol you got me

[Hnichols]

It's your car's way of saying it wants to be driven more ...

[Tippy]

I'd say you have leaking injectors.

1. With key off, no more fuel should be injected
2. Hard starting indicating fuel pressure bleed off.

[pharlap71]

even with leaking injectors (probable) it still needs ignition so you probably have carbon build up also, it is glowing.
PS- There is a chance when it is "dieseling" it is running backwards! Not good

[Tippy]

Yes, carbon being ignition point. These motors develop a lot carbon due to their inherent design.

I agree, the chain tensioners only like to work in the correct direction. When you turn the engine backwards, it seems like the chain wants to jump the sprockets. Not saying it will, but it makes you feel uneasy when looking at it while turning.

[Chuck.H]

Something is leaking fuel into the manifold, either an injector or the fuel pressure regulator or dampner.

You can remove the vacuum hose to the regulators and use a hand held vacuum pump to see if they hold vacuum (as they should). Leaking injectors you can possibly fix with some seafoam or techron and a 'not-safe-for-your-license' drive, but best to send them out to be cleaned.

Chuck.H
'89 TurboLookTarga, 334k miles

[Tippy]

Damper is on right, FPR on left. Like Chuck said, if you smell a strong odor of fuel in either vacuum line, it is more than likely the culprit. You may smell a faint smell after all these years. Mine do.