1G Mis-fire/Hesitation/Stalling...Negative Timing!?

[jonseclipsegs]

I recently purchased a 90 TSi AWD and have been trying to get it on the road. It has 139,000 miles and ran nicely before the previous owner parked it for about a year.

Since I got the car running it has had a hesitation/mis-fire over 50% throttle and stalls at idle most of the time after warming up. This isn't a mild mis-fire but one that shakes the car and stutters dramatically. It will idle nicely when cold but barely idles when warm.

My logger is reading negative timing during this bad idle, about 3-7 degrees at about 500-700rpm. In addition my logger reads no knock at all during anything I have done (bad sensor or normal with stock car?) When the car corrects itself or raises the idle itself the timing advances to a normal positive level.

I have replaced: spark plugs and wires, power transistor, coilpack, fuel filter, MAF, all inj's are functional, thermostat, coolant temp sensor, oil, coolant.The CAS has never been touched as far as I know and is firmly in place and the ECU looks to be in good condition, inside and out.

Anyone have any ideas or how/why I am running negative timing?

 

[DSM4me44]

Sounds like a boost leak. Just about the most common cause of a DSMers problem sometimes. This term is all over the form, so do a search if you need more info. Purchase or make a boost leak tester and do a test. Make sure to use a bottle of soapy water when your doing the test. That way anything that has a leak will blow bubbles under pressure.

 

[bwild97]

Have you checked the plug wires? A bad plug wire will leak spark under load and make the car shudder violently. Even new plug wires can have a small pin hole, enough to let spark out.

It could also be possible the ECU was swapped out for a later model ECU since you have '90s model there are two wires that need to be reversed, can't remember which they are.http://www.ecanfix.com/users/mdhamilton/ecuconversion.html

 

[jonseclipsegs]

I did a boost leak test and there were no noticeable leaks at all. I have pulled the ecu and it looks to be fine, plus the car was essentially purchased from the original owner who never touched the ECU(or anything).

 

[laserspeeddemon]

Hmmm, I wonder if we could get the car to my buddies house? How far are you from Alexandria?

 

[jonseclipsegs]

Not very close to Alexandria. I'd guess at least an hour. This might not matter for much longer, I have an offer on the car to buy this weekend...