High Idle When Warm

[xveganxcowboyx]

My car has always idled high when warm and I'm sick of it. I just got my new stroker in and want to get it reasonably tuned and drivable and this is screwing me up. Here's the pertinents:

Always idled high (especially in warm weather). This means for 2 1/2 years, from completely stock to where it is now.

Did it on stock MAF. Now does it with MAFT.

Did it with stock throttle body, cleaned, changed seals (2 years ago), changed sensors, finally installed QPR block off plate. Still does it.

This is the third engine, no change.

Did it with original cooling system, does it with aluminum radiator and slim fans (though the idle rises more if the engine temp rises above normal on either setup)

Did it with stock EGR and with QPR block off.

Did it with original vacuum lines, now does it with just Cruise line, Boost gauge, BOV, stock FPR line.

Did it with boost leaks (when I bought it), does it now with no leaks.

Did it with old O2 and replacement O2.

Did it on original fuel system and does it on EVO injectors and pump.

etc.............


The car idles fine on start-up (a little rough/low now with the TB block off) and is fine up to about 170 degrees coolant temp. Then it starts to rise. It takes 5 to 10 minutes for it to get from ~800 rpm to 2,000 or more. It's been over 3,000 rpm in the past. I can take fuel out of idle range, but then it idles too low to start properly when cold.

If it's at all helpful I've also always had a crappy voltage issue. Starts out between 13 and 14 volts, but lowers to 12-13 depending on accessory use after warm-up (follows same pattern). Not sure if it has always done this, because I haven't always had a volt gauge. Alternator is 1 year old 90 amp model.