Miata Turbo Forum - Boost cars, acquire cats.

Before I explain I'm 99% sure I've read every idle thread on here. If I've missed one then it was simply oversight and not lack of searching.

My car is the 1.8 so I have the correct TPS which means many of the fixes in other threads don't apply to me.

Ok, so three weeks ago my idle was perfect. Then I got my a/c recharged and I noticed that I started getting epic idle droop, down to 200 and sometimes even less. I've given up on getting the car to idle with A/C so I simply turn it off when I come to a stop so it doesn't stall the engine.

Then, even if I never turned the a/c on the idle droop would be there, every time, every stop.

So I played around with my idle settings to try and fix it and every change I made, no matter the field, either made it idle worse (swaying idle) or did nothing at all. If I tried to change the idle speed it would do nothing. It didn't matter if I raised or lowered DC or Dashpot, all it would do is cause the RPM's to rise and fall.

As my last resort I backed out my idle air screw last night. It finally idled fine with no droop.

Wake up this morning and the car is swaying between 1700 and 2200. I screwed the idle air screw back in and it was, once again, idling correctly. Then tonight I cranked the car to find it constantly idling at 1500.

So, any ideas? I've followed any recommended advice I could find but none of the fixes have worked so far. I also think it's very odd that the car refuses to idle at the speeds I set and whenever a change does make a difference it only serves to make the idle sway drastically. It's also a bit unnerving how the idle will change with no input from me.

Also, for what it's worth I've tried returning all idle settings to the settings I was previously using (they were the ones Joe Perez posted).