Strange Problem?

VBasso · 09-10-2007

I'm new to the forum here but have been a DSM owner for many years. A few years ago I bought a 92 TSI AWD from Kris Ali that already had a lot of modifications. It was running well for some time but last July it started developing a problem that to me seems pretty strange. When you start the car it will just rev up to about 2-3k and then just run back down to 500 and sputter out. Restarting it multiple times will have the same result as the first time.

The only way to get the car to keep running is to keep tapping the throttle over and over causing the the car to rev up and down continuously. Sometimes doing this will get the car to go into an idle surge from about 500-1500 rpm but often dies when it gets down to about 500 rpm. Holding the throttle to the floor will sometimes get the car to keep barely running at about 500 rpm.

When the problem was first developing on some days it would start up and run just fine. Possibly temperature or humidity related? But it seems like it has gotten so that it will now do this strange thing every time I try to start it.

It's not my daily driver so it sits around without being started a lot but does have fairly fresh gas in it right now. I really don't know what is causing this problem. Throttle position sensor? Bad injectors? It has run very rich since I got it and has fouled out a few sets of plugs but there is a fresh set in now.

Mods are:
HKS VPC (yes some people still have them)
Big 16G
RC 550s
Rewired Walbro 255
3" turbo back

Sorry for the long post, this problem is just really driving me crazy and any input is appreciated.

Thanks

**Goat Blower** · 09-10-2007

Do you have access to a pocketlogger? It should be throwing a code, find out what that is.

VBasso · 09-10-2007

Can it throw a code without the CEL coming on? I did have a pocketlogger connected a few times when it was doing it to look at graphs but I don't know if I actually tried to retreive codes since the CEL wasn't on. The batteries in my palm pilot died and I'm not sure how to get the MMCd program back on a palm IIIxe. I'll look into it.

VBasso · 09-10-2007

Well I got my MMCd working again and I just went out to try to get a code and it showed no active or stored DTCs.

xveganxcowboyx · 09-10-2007

Hopefully you've tried this already, but boost/vacuum leak?

**JET** · 09-10-2007

Yep, sounds like a boost leak. If not, the BISS screw may have backed out or the o-ring for it went bad. Is this the green one or maroon one?

VBasso · 09-11-2007

I have checked for boost leaks, I couldn't find anything major, small leak right at the throttle plate but it's had that since I got it. I've fiddled around with the BISS screw some and I think it is set at a pretty reasonable level right now. This is the maroon one.

VBasso · 09-13-2007

Well it acually decided to start last night, lots of idle surging at first but then it settled down somewhat once warmed up. It seemed to be running fine on a short little drive except for running pig stinking rich the whole time. Any further insight from anyone? I'm really hoping I can find someone who has experienced this problem or knows someone who has, its really baffling me so ask your DSM friends if you could.

xveganxcowboyx · 09-13-2007

I'd go through and check the electronics that govern fuel and air. MAF, TPS, ISC, O2, etc...