Quote:
Originally Posted by Ecky
I wonder if there isn't some mechanical difference, such as the IACV, or perhaps the idle screw should be adjusted differently for a manual car?
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I think you may be onto something there. I have an Acura RSX-S throttle body, I wonder if that could have something to do with the high idle. As a test I tried taking the idle screw all the way out so the throttle closed completely, which made no difference other than causing the throttle to stick closed. I also swapped the electronic IACV actuator to the D17 one and cleaned the IACV, which again made no difference.
I'm thinking I will see if I can retrofit the D17 IACV onto the K20 throttle body to completely eliminate it as a possible issue, but I have a hard time believing that's the problem because the ECU seems to be in control of the idle speed. If it wasn't, I would think turning the AC on would force the idle RPM down instead of slightly increasing it. And while stationary, the idle is perfect.
However, one interesting possible explanation I read last night is that the ECU's ignition timing curves are different (more advanced) while in motion compared to while stationary, so if excess air is entering the engine through a vacuum leak, the ECU may not be able to drop the idle down to normal by closing the IACV completely. I checked for vacuum leaks and found none, but still interesting and potentially useful information if it's correct.