nh3

First off, my car runs beautiful. No problems throughout the rpm range. My problem is the first 3 seconds upon starting cold like when sitting all night. It stummbles kind of like a carburated motor with a bad choke adjustment would. The only way to avoid this on start up is to apply a slight amount of accelerator pedal and she won't do this but that is just masking the problem. After getting through the first 2-3 seconds all is fine. Any ideas?

nh3

Olli Snellman

That's quite unusual! Might be leaking injectors.

Olli
'88 951

Jonathan Martini

I've taken two long trips in the past month and both times the first time I tried to start up the 944s it did exactly what you discribed. Stumbled for a few seconds, even died if I didn't apply some gas.

Difference is that from day to day this doesn't happen on mine.

My current guesses:
* fuel injectors
* computer
* may have something to do with not being garaged (water/condensation somewhere that gets burned off).
* low battery from sitting so long.

Since it does start and there's no starter hesitation I doubt the battery being low is the problem.

That applying gas fixes it makes it a fuel problem in my mind, although it could also be the computer/sensors fouling up due to condensation or something else from sitting so long. This would have the effect of the idle being set wrong, causing a stumble.

I just crossed 100,000 miles recently, so I'm due for the standard tune up stuff anyway. I figure replacing the plugs, belts, air filter, and getting the injectors cleaned will take care of the problem, so I'm not really worried about it. I've already replaced the plug wired recently as well.

Love to hear if you figure it out though.

Cheers!

Melchior

Try cleaning out the throttle body housing with some Throttle Body Cleaner. Also, try the AFM to see if it is dirty.
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scular

Definitely start with a tuneup or at least inspect the parts, cap, rotor, wires, and plugs.

My car started throwing hissy fits in the mornings, even worse after I drove another car for the weekend and just let her sit in the driveway (properly covered, of course). It turned out to be corrosion between the spark plug and wire clip. I cleaned that out and now she doesn't mind so much if I drive another car for the weekend. But I have never let her see me in a newer Porsche. I can't imagine what would happen.

nh3

I'm hinting towards a leaking injector. Well here is how my 10 year old describes my engine during cold start up. "Boom Ba Boom Ba Boom..Vvvroom" It never stalls during this, just a unstable low rpm for 2-3 seconds after turning the key. I did all the tune up stuff 2k ago as a precaution but at lunch today I did get jolted by a plug wire so that is a possibility along with the idle stablizer valve. It's nothing I'm gonna loose sleep over since it is only for 3 seconds first thing in the morning but will motivate me to plumb in that fuel pressure guage I always wanted!

Melchior

If your engine oil smells like gasoline, then you have a leaking fuel injector. It gets in there when the engine is cold and the fuel seeps down the sides of the cylinder and into the oil.