scmguru

(xposted to PP)


I've got my cold idle sorted out and the car now has a proper cold idle warm up.

However, I seem to have a new problem!

If I let the car sit for 1-2 hours (65-75 degrees), it starts immediately and idles horribly for about 5 minutes.

Duting the 5 minutes, I have a low (lean) 500-600RPM idle, complete with popping when I give it gas etc.. on warm startup.

I turned the the a/f screw about 1/8th or so towards rich, it seems to get rid of most of the popping, but the idle is still low.

I've checked and re-checked all of the WUR pressures and have performed a fuel leakdown pressure test which passed just fine.

Hot starts (i.e under 30 minutes) are fine.

System/WUR pressures are as follows

System Pressure: 6.7Bar
Cold Control Pressure at 20 degrees C: 2.1Bar
Warm Control Pressure: 3.75 Bar

Leakdown fuel pressure test:

10 minutes - 2.1Bar
20 minutes- 1.6Bar

It's almost like the WUR thinks the engine is warmer than it really is (because the WUR is still warm) and as a result, is causing a lean condition.

Thanks for any insight!

Mike