mike10562004

yes helped me out too

DarylJ

Yeah, sorry, should have been more specific. The part about wrapping a paper towel or shop rag over it should have been explained better - you need to leave a 2 or 3" "tail" and aim for the passenger's side with it - that gets you to the bottom.

That's not really necessary - running the car to temperature and parking it overnight is what's causing the issue, which may be coolant or may be fuel. By duplicating the conditions, you are doing an accurate test. Besides, parking your car after having it up to temperature _IS_ a cooling system pressure test (at slightly lower pressures than you might do with a "proper" pressure tester).

supes6

Update:

I just finished last weekend with the head gasket job. My old head gasket looked pretty good and didn't show any signs of leaks into the cylinders. Also some carbon buildup on the pistons, which I'm told would have been cleaned off if there was water leaking in and burning off. So, it looks like the headgasket wasn't the source of the stumble problem, although I did need to pull it to drill out a broken exhaust stud. I'm still not sure why I was so low on coolant.. could be I forgot to turn the heat on when I bled the system but I can't remember.

So with that said, I have a new theory on the stumbling problem (which is still there). Now that it's getting colder out it seems to be a little worse and I'm back to looking at the DME temp sensor. I have a new sensor installed but I'm wondering if the old wiring could be a problem. Take a look at this thread here

black944 turbo

Thanks supes, Let us know what you find on the connector and how you fix it. I posted on the other thread, I know it is 3 + years old but worth a shot.

kennycoulter

chasing the same freaking problem for 4 years now...
also replaced everything except the fuel line screw thingee. hopefully someone finds the actual problem.

FRporscheman

Until someone proves me wrong I'm still going to (wishfully) lean towards something wrong with the open-loop function and the fuel being too rich.

Maybe I can hook my car up to the smog machine when it's cold and stumbling, and watch the emissions as it stumbles. High HC could indicate rich mixture... what could indicate steam? Low CO2?

kennycoulter

i was wanting to test the hose to charcoal can problem on start up....but with the weather getting colder here, things got worse....i "found" an air leak under the manifold or around the throttle body.

i can't seem to pin it down, but i tightened my hose clamps with no different results.

can the idle stabilizer body go bad? when i replaced mine, i replaced the hoses too, i know they are in close proximity, but do not look cut up or anything.

has anyone else cured their problem before winter hit?

Grandpa#3

There has been a lot of talk about the ICV. Below is a way to test it. Hope this is a help to you all.

http://www.texasblake.com/porsche/tech/icv.html

http://the944.com/main.htm

Cheers,
Larry

ccg951

Found this thread as I'm in the same boat. If it is below 59 deg. F outside my '87 951 will not start. 75K miles and runs fine once it starts save for a slight "lean" hesitation for maybe 2-3min. in the morning. Have replace most of the vacum lines, replaced plugs, wires, cap and rotor last night, no improvement. Installed fuel pressure gauge at rail and psi seems fine.

DME Temp sensor replaced this summer and had no effect on cold engine hesitation. Going to check DME temp sensor wires this week and install original DME temp sensor as test.

I suspect my issue is a lean condition. I believe this could be verified with a very small wiff of starting fluid or evern a small wiff of fuel sprayed into the intake. If this works then I just need to figure out what is causing the lean condition.

peanut

has anyone looked at the cold start valve yet in connection with this problem ? if the injector is dirty or sticking the engine would run a little lean until it started to warm up and the mixture stabilises.
I'd remove the cold start injector stick it into a clear jar and try cranking the engine over when cold and check the cold start injector is working properly. The associated temperature sensor should be checked to as it may be mis-reading the temperature of the inlet manifold.

kennycoulter

my problem (so far) has been a cracked hose slid over an after market(too big) plastic elbow that was under the intake. also had an intake gasket that was slid out of the way that must have finally cracked.

i was chasing it down as the stabilizer, but found those problems after taking the intake off.

good luck to you guys.

ccg951

Started trouble shooting again last night, pulled DME relay an jumpered 30 and 87b to see how fast fuel psi built up, all looked well. Replaced DME relay and it started but died after a few sec. Jumpered again, replaced relay and started then died. I grabbed my old DME relay out of the glove box (replaced it this summer just because and kept the old as a spare) and she fired right up. Started fine this monring and I think with 99% certainty I've fixed the prob.

Never suspected the relay as it was new this summer and it started fine above 59 deg and would not have any issue until is sat cold (below 60 deg.) overnight.

Go figure, have the fix in the glove box the whole time and I've been dealing with this since late Oct.

peanut

glad you got it fixed and for nothing too great result.

The more I read about these relays the more I realise how cheap and nasty they are. Time for a better solution methinks

ccg951

28 deg F. all night and she fired up this monring without hesitation. Now I can focus on things I want to do instead of a have-to-do no start problem....

peanut

brilliant !

having spent the past 2 months with a no-start problem myself I know what you mean. Its a huge relief.

Have a great Christmas everyone