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Old 10-31-2002, 07:58 PM
Posts: n/a
Guys, your idle problems may be idle problems, in which case do the cold start checks in the trouble shooting guides, such as EHA start mA and decay rates, Coolant sensor resistance at various temps, cold start valve leakage, system residual pressure, buildup time, and limits. Also, verify the operation of the idle speed air bypass valve, or indle speed control valve ( you know, pinch the hose off both cold and hot to see how it affects idle speed). If all those things are in limits, you probably don't have an idle speed or start-up problem per se, but another problem, which when compensated for, becomes an idle speed problem.

For instance, adjusting mixture while ignoring a vacuum leak or a malfunctioning injector, weak cylinder, bad plug, etc, is a sure way to ruin the systems's ability to compensate for the non-standard needs of start-up and warm up conditions. I've not seen anybody talk (in this string) about airflow sensor rest and zero positions, centering in the bore, and so on. Everything, and I mean everything, is at its worst ability to compensate under cold start conditions.

You need to have the system pressure gauges and the ability to use digital multimeters, as well as skills at analyzing spark plug coloration to get through this. I had to rig up a way to test my injectors by building a fuel distributor tied in to the vehicle fuel system but still allowing me to observe the individual patterns and volumes of fuel. Once I did that, and all other checks were satisfactory, I had to completely readjust the mixture settings at operating temperature idle, because before that time the lambda system was trying to balance three good cylinders against one bad.

How about cold compression vs hot? How about first compression stroke in each cylinder vs maximum value (5 strokes)? I've used the "1 vs several" with good success to find valvetrain problems.

Sorry for the soapbox oration, but you seem to be running in circles by looking for solutions to symptoms instead of finding and repairing root causes.
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