Gremlin

[Campbell]

Just when you think you have half an idea what you are doing.. I spent the weekend chasing a gremlin I never got sorted out: (ITB 1.8 Scirocco)

My first 3 laps were terrific, the car was running great and I was already seconds under my quickest time ever and then, I began losing power and then at 5700 rpm in 4th the car would stall out and my fuel/air meter went black. If I let off the pedal it would come back. For the race I changed the pre pump (was convinced it was fuel starvation), had the same condition only worse, power loss from the get go and stalling after the car was hot 3 laps in. Put in a new primary pump that night and for the first session the next day.. same thing. For the final race I changed the freq valve and computer, no change and the condition morphed into not being able to go over 5000 rpm in 3rd, 4th or 5th. I then began to realize it was most likely a bad distributor? was not blowing any smoke, I will check compression but am sure it is okay.

Question is, how best to troubleshoot something like this at the track? I think I got off base by thinking the fuel/air gauge was telling me something by going black - I now think it went black because the engine wasn't firing, not that it had gone completely lean? this is such a bummer.

Also, since the fuel pump I took off was still good I will keep it as a spare - I don't want it to rust or freeze up, what would be the best way to prep it for storage? thanks

[JonL]

Originally posted by Campbell@Aug 15 2005, 01:07 PM
Just when you think you have half an idea what you are doing.. I spent the weekend chasing a gremlin I never got sorted out: (ITB 1.8 Scirocco)

My first 3 laps were terrific, the car was running great and I was already seconds under my quickest time ever and then, I began losing power and then at 5700 rpm in 4th the car would stall out and my fuel/air meter went black. If I let off the pedal it would come back. For the race I changed the pre pump (was convinced it was fuel starvation), had the same condition only worse, power loss from the get go and stalling after the car was hot 3 laps in. Put in a new primary pump that night and for the first session the next day.. same thing. For the final race I changed the freq valve and computer, no change and the condition morphed into not being able to go over 5000 rpm in 3rd, 4th or 5th. I then began to realize it was most likely a bad distributor? was not blowing any smoke, I will check compression but am sure it is okay.

Question is, how best to troubleshoot something like this at the track? I think I got off base by thinking the fuel/air gauge was telling me something by going black - I now think it went black because the engine wasn't firing, not that it had gone completely lean? this is such a bummer.

Also, since the fuel pump I took off was still good I will keep it as a spare - I don't want it to rust or freeze up, what would be the best way to prep it for storage? thanks

58395



hi campbell, jon here. do you know if your coil is ok. what motor? 1.8 8v or 1.8 16v?

[racer14itc]

I'd be suspicious of the computer. Sounds like the full throttle enrichment signal is involved, or the computer is malfunctioning. If you have another module to swap out, maybe that might tell you something.

Mark

[Campbell]

It is a 8v, I put a new coil in a few years ago, hadn't thought about that. During the last race session I actually pulled into the pits and swapped computers, it just worsened from there. It seem to crap out when it was floored, but only over 5k rpm. I think when I lifted the rpms would drop and it would run again. It was so frustrating, why couldn't whatever was wrong just plain break!!!!

[Bill Miller]

Originally posted by JonL@Aug 15 2005, 03:42 PM
hi campbell, jon here. do you know if your coil is ok. what motor? 1.8 8v or 1.8 16v?

58413



I think Mark has it. I chased a similar problem on my ITB Rabbit GTI a few years ago. Would start breaking up at ~6k, and would steadily move down till it got to 4500. I noticed that the shift light would flash in sync w/ the break up. Changed every electrical compoent in the car (coil, wires, dizzy, etc.) Nothing worked. Put a new K-Jet box in it, and it was all good!..

[madrabbit15]

Campbell,

You are leaning out at high RPMs. Try turning the little 3mm allen screw at the FI unit .5 turns clockwise. At idle it will run like crap, but it will fix your high speed miss. Besides how it runs at idle is not what we care about anyway ;) Until you get on a dyno and tune the regulator you will just have to deal with it. This is very common with us CIS guys when the temps get really hot in the summer time. I had this problem at Atlanta a couple weeks ago and after playing with it all weekend it was def. was fixed it.

Derek

[Dave Zaslow]

I had a similar problem in my Rabbit GTI. It was the Hall Sender in the distributor.

Dave Z