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Discussion Starter #1
I have this posted at HT also, but I figured more opinions couldn't hurt...

It's a 2000 prelude SH. SK2 TB, CAI, header and cat back are the only things that might apply.

When I'm driving around in any gear, any RPM the car tends to accelerate/decelerate on it's own. I'm not doing anything with the gas pedal, and it's not a significant change, but it is noticeable. It does each for a few seconds, then switches. It seems to do the same thing if I'm sitting in neutral and try to hold the RPMs at a specific point. Example: If I push the gas pedal and put the RPMs at 2000, the car will sit there for a few seconds, then drop to 1200 or so, hold for a few seconds, then climb back to 2000. All the while I'm not doing anything with the throttle.

I didn't really notice this particular simptom until it got hot here (115 today) and I had the A/C blasting. Although it does it a little even when the AC is off. seems to only be a few hundred RPM difference.

I have also noticed that the RPMs do not rise at all when I turn the AC on.

I recently replaced the IACV with a known good one, I have tested the TPS repeatedly as specified in the service manual. Months ago I tested the AC signal to the ECU and it checked out ok.

Aside from retesting all of those components, which I plan to do when it cools off a little, is there anything else I should check out? I have a new ECU on the way just to verify that as well.

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