Hello

We were in the process of learning how to adjust the base idle on our 240. We tried to disable the ICM by grounding the appropriate wire per our manual. We noticed that there was no change so we unplugged the ICM. Surprise , ICM is not working. The car really runs really well except that once in a while the idle seems a little marginal. It seems that the ICM is there for situations where an engine is under more load than the base idle will tolerate.

Please help with these questions.

All other things being correct such as a clean throttle body and all other adjustments correct :when your foot is off the gas pedal and the throttle butterfly is returned to its stop position is there a small gap still between the throttle butterfly and the actual body of the assembly to allow the slightest air to the intake. I was told yes. Also told that a dirty throttle body accumulates enough buildup to close that small gap. Told that the TPS thinks the throttle is basically closed but allowing a small amount of air thru that gap.

What other items other than than the AC being used would require a greater idle than base idle.

Could there be some other item such as the TPS, base idle, vacuum leak which is making our 240 run so well with the ICM completely disconnected. Basically would all 240s run this well with the ICM disconnected provided the AC was not turned on.

Our shop cut up an old Volvo ICM to see what it looked like. It had a small little motor which seemed to move a solid lever to change air flow. My question is : Is there any forced air going out of the motor or is the motor merely restricting or at times opening a path for air to be sucked in by the vacuum of the engine. My thought is : If there is no forced air by the ICM it is possible that our ICM just happens to maybe be stuck in a position which is allowing our car to run ok. Ok just at this time given no AC needed and who knows whatever else just happens to be right. If this is the case than a Bad ICM could possibly be stuck in many different positions thus affecting other 240s in a variety of less pleasant ways.

Finally, Having an ICM cut into pieces I really expected to see carbon and guk as around the the throttle body or flame trap plumbing. Surprise, it was old but the inners were clean. No guk. Therefore I started wondering about people speaking of running cleaner through theirs. If anyone knows how to clean an ICM please tell us how. It looked like the only benefit to the ICM would be some kind of WD40 or similar lubricant rather than a throttle cleaning product. Because the cut up ICM seemed to fail because of friction between the movable lever within and the body of the ICM. Not any type of oil vapor or combustion buildup.