f8vr993

Help!
About a month ago, I was able to start the car right away like normal but as I was pulling out of driveway it stalled... Got it re-start so didn't think much. Following week it did it again but was able to get going again. (I don't drive everyday)
Next time was when I knew something was not right... It started right away but stalled immediately and would restart at all. Waited a while then got it restarted with lots of revving to keep it running. I was able to warm the engine enough to change gear and drive home.(it seem like car stalls right after when i shift into gear/drive...btw, I have a tiptronic)
Now car won't even start at all, it would crank but won't spark or turnover... Have searched the forum but not much other than ISV,FPR. I'm just about ready to tow it to indie shop near by but before I do, I like to hear any advice from Rennlisters out there who might have clue or suggestion.
Yr-95
91k miles.

techman1

Hold your foot on the gas, barely cracking it open. Then try to start, while holding it open.
If your ISV is stuck in the closed position it would exhibit the problem you describe.

IXLR8

Have you actually tried swapping the DME for a known working unit? Its a 10 second job.

mgianzero

I'm chiming in as I am a friend of the owner.

Are you recommending a DME relay swap, not a DME swap? We did that with no luck. Doesn't run with 2 different DME relays, one being brand new.

What's also funny is a known engine rebuilder in the area came over last week to take a peek. He put his Durametric on the car (version 5 an 6) but couldn't talk to the DME. This is an OBD-1 car with an OBD-2 connector, so maybe this falls into the category or unique cars the Durametric cannot identify.

That being said, we abandoned the analyzer and then noticed the MAF hose clamp was loose. He tightened the clamp and the car started right up, twice, and ran smoothly for about 2 minutes. We turned it off and assumed that was the problem.

We came back out about 2 hours later and the car turned over very easily but again showed no sign of starting. We "think" we smelt fuel but cannot hear the fuel pump. But I admit, I can stand right under my car with it running and can barely hear it. Maybe need to jump the DME relay and see if I can hear it.

So it appears could be either the typical no fuel or some sort of electrical problem. We're currently looking for a Porsche analyzer to take a quick look, but until then it's just a guess. Guess we'll check for spark, etc. next time I have a chance to look at it. It's just puzzling that it would do this.

IXLR8

Yes, a DME relay swap. I know you popped a new one in, but after taking the cover off a couple of failed units, their solder joints are pathetic. Check your new one as well. Try using a jumper wire. You should carry one in your kit as well.

If one hose clamp was loose, what other hose clamps might be loose as well. Check them all.

And chance of doing a fuel pressure test and fuel pressure retention test?

mgianzero

What's the "jump" test to turn on the fuel pump? I used to do this on VW's long ago, but haven't done it on a 993. Can you tell me the pin numbers I need to cross?

I don't have access to a full pressure tester at the moment. What if we just crank the car and pop the fuel rail valve, shouldn't a fuel squirt signify the fuel pump is "at least" working?

IXLR8

30 - 87 - 87b bypasses the relay.

For the pump only, it looks like 30 - 87b and make sure your fuse is OK.

Mike J

Maybe we should check for paper towels? :-)

Ok, on the surface, its either fuel or spark.

Spark is easy to find - pull the coil line off the primary distributor cap and see if there is a spark when the engine is turning over. If yes, then it's likely fuel.

For fuel, you can definitely check for fuel pressure - you are right, you can let off the feed to the fuel rail (best place is just besides the A/C pump) and see if fuel squirts out - be carefull, has is quite flammable.

If you are getting fuel and spark, then we need to go deeper.

Marc, how much assistance can you give to dig into it a bit more mechanically?

And no, I am not driving down to Orange County on this one....LOL!

Cheers,

Mike

Mike J

Oh, any recent work lately?

mgianzero

Thanks Mike. Thought you'd chime in. You are always a very helpful fellow reenlister.

I think I'm going over my friend's home tomorrow to take a peek. Will do a quick fuel and spark test to see what I can find. Wish me luck!

f8vr993

For Marc's suggestion I've replaced the #26 fuel pump fuse and just by chance noticed a wire(not sure where it goes...) was loose from the battery. Hooked it back up and Voila! car starts!!! Go figure...
Let me give it an another start in the morning to make sure.

Mike J

Marc commented about some sort of third-party alarm system - ?? Perhaps?

f8vr993

Bingo!

mgianzero

Well, I'm glad we got that one figured out I think.

He's going to bring car over tomorrow to double check things.

The car runs a little rough, though. I was suggesting that, since he had a loose MAF that was later tightened up, perhaps the DME can now correct for this erratic A/F ratio and it will smooth out once it "learns" the new mix. What do you think guys?

Mike J

I guess depends on what "rough" is - if the DME is correcting, its usually running the car rich, which means it should be pretty smooth.

Take a look tomorrow and see what you think.

Cheers,

Mike