StupEd05

Car has been down for a month now. And I and many other people are stumped. I have had a few other threads on individual problems but I am trying to consolidate this all into one problem/question.

The problem:

In the beginning my radiator hose met the alternator pulley, spraying vast amounts of freshly bought coolant all over. Car sat for about 3 days while waiting to put in new hose. Put new hose in and car started up fine like always. Drove it 10 minutes into town, sat around for a while then drove it for 20 minutes or so into the nearest large city. While in the Wal-Mart parking lot it began to idle erradically and I gave it gas and it dies with a slight backfire. Would not start up at all, not even fire a few times. Got it home. Put new J-boot on it as the old one was cracking and becoming hard. Cleaned and resealed injectors. New(er) cap/wires/plugs/coil. After a few attempts she starts up and runs good. Got 10 minutes into town and it begins to hesitate and stumble horribly. Very jerky acceleration, turned the corner and bam it dies. Let it sit for about 20 minutes and it start up. Get 3 blocks away and it stumbles/dies/backfires. Wont start back up. Tried many many new spark plugs and many different gaps. 90% of the time it doesnt start, but occasionally it will idle for a bit and then die. Quite often I will be cranking it for about 10 seconds at a time and when I let go of the key it will fire about 2-3 cylinders and do nothing (kinda like dieseling), but when cranking nothing, only right after cranking.

Fuel pressure: (jumped DME) 36psi
Fully charged battery
-17in hg at idle (vacuum at FPR)
Tried swapping DME
Got good spark
Got fuel to the rail
Tried new fuel
Tried Starter fluid
Timing is on (thank god!)
Ref. and Speed sensors checked out Good
New fuel filter
AFM Good (swapped with known good, and all volt/ohm readings are right on)
Replaced all suspect vacuum lines

Im pulling my hair out on this one! Has anyone had a problem similar where it rarely starts, but when it does it runs good for a little bit then dies? If so, WHAT DID YOU DO? I can't take this much longer, its almost time to call a mechanic!!!

Mike Murcia

AFM?

StupEd05

We tried that a couple weeks ago. However, Scott thinks we should try it again. When it actually does idle, as it begins to die I hear a loud LOUD sucking noise through the AFM, sorta like its trying to get a LOT of air but cant so it dies. Good answer.

Any other ideas?

Jason_86_951

My guess would either be the TPS or reference sensor connections. Did coolant hit the TPS or any of the wiring at the back or the block? Coolant will advance corrosion on electrical equipment. If some got into the anything important it could cause havoc.
Try pulling apart eletrical connector and looking for corrision. Be cafeful those connectors get brittle after 15-20 years.
Just a guess, but I hope it will lead you in the right direction.
Jason

StupEd05

Not sure if coolant made it all the way to the back of the block, but I wouldnt doubt it. It was spraying out pretty good. The TPS is the little black box right under the Throttle body correct? Could all that coolant spraying at the alternator have fried the alternator? Or are the alternators pretty liquid proof?

Geo

Yeah, this is what I was thinking. James Weaver (goingboeing737) had a similar problem and it turned out to be the reference sensors. He would go around corners or hit a bump and the car would die or drive like someone pulled 3 plug wires.

xsboost90

check the reference sensor wires...plugs right behind the cam box..

Lowcountry944

I have to agree with Mike, it sounds like the air flow meeter. I had mine go bad a few months ago on a freashly rebuilt motor, and man, that thing sputtered, backfired and smoked like a 20 year old car that hadn't been started in a decade. I wouldn't be surprised if the AFM got coolant in it.

StupEd05

hmm... true, the coolant could have fried it. I took a look at the tracks on the afm and it looks like dirt and junk down in the little indentation of the track. Is there a way to test the signal coming out of the AFM? I guess I will head over to Clarks Garage and look around.

Thanx!

StupEd05

IIRC, I remember reading somewhere that the DME gets some sort of signal for when the starter stops, once it knows the starter stops it checks for a signal from the AFM. Anyone know about this? It could have something to do with the dieseling. A lot of times I will crank with nothin happening and as soon as I let go of the key it fires about 3 times. Like it starts to get a signal but loses it and quits

xboost - The plug connectors at the back of the cam tower are cracked. Along with the Oxygen sensor plug right behind them. However, I am pretty sure the sensors are good and the DME is getting their signal because without their signal I wouldnt have any spark, right?

StupEd05

AFM checked out fine with volts and ohms being what they should be, will still try swapping out though. Any other ideas?

PorscheDoc

the tach also bounces during cranking.

StupEd05

TPS also checked out fine on ohms...

Phil Coomber

I would check to ground strap at the rear of the engine to the firewall.

Phil

Travis - sflraver

Ground strap could indeed be the problem.