I experienced a problem last week and thought I would share it.

Car was running great- with steady idle and acceleration. But then one day after a run the car was parked for an hour and when I tried to pull away there was almost no response - like the engine would not come off idle. It was similar to what happens when one wheel is on ice and the system shuts the throttle down.

Then when I pushed harder on the throttle the car responded with a sudden acceleration and all was fine until the next corner - the car would not come off idle till I pushed a bit harder on the throttle.

Under the hood I manually tried to operate the throttle and found it "sticking" in the closed position until I applied additional force. But this was only when the car was hot, and only after parking for a while so that the engine heat had thoroughly heated the throttle body.

I removed the aux throttle, and the idle control valve so as to be able to access the main throttle plate. There was a moderate ring of black residue around the throttle body where the throttle plate sits when closed. While this also collects in the idle control valve I have always cleaned that every 2 years but never went into the throttle body till now since you have to remove the aux throttle (at least you do on the old models with the manual throttles).

Cleaning that out solved the problem. It can be a bit difficult to clean. You need to use a solvent like "carb cleaner" and get to both the lower and upper areas - including the edges of the throttle plate itself. After I was done I tied the throttle open overnight before re-assembling the components so that any vapours would clear.

Keeping the throttle and the idle control valve clean can make a significant difference in idle and acceleration control.

Cheers
Jim Cash

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