Can the idle stabilizer valve be bad and still pass the Bentley tests?
I had the same problem with my '86 GTI (CIS-E). Sometimes it idles fine, but many times when I let off the gas it drops almost to 0 RPMs.
I haven't replace the O2 sensor, so it could be bad and I haven't checked the timing, but I've done most everything else:
-Mike
I had an idle jump on mine, turned out to be a timing issue. When the motor was cold it wouldn't do it, when it warmed up we believe the coolant sensor sent false readings to the ecu causing the distributer to advanced then retard constantly, this is what caused the idle jump. Check your coolant temp sensor as well.
As has been said probably a dozen times in the last year...
Disconnecting the coolant temp sensor or the oxygen sensor merely sets the car into a different operating mode. It does not just run w/o that sensor it runs without other sensors, too. Rather than attempting to calculate the right amount of fuel (and then adjusting-- this is known as feedback) to squirt it uses a map stored in the computers memory to try and get close.
This does tell you whether the problem might be in the feedback system. But I certainly wouldn't bet my house on that.
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