well .. upon startup my car idles at 1200-1400 rpm and i dont think thats normal...

I got a new exhaust cause the old one was leaking and scrapping on speed bumps, with the new exhaust the car breathed better and its rpm at idle was 800 which i find is normal, but after about a week with the new exhaust its rpm on idle went back to 1200-1400

and i honestly have no idea whats going on, no mechanic i went to has any idea about the car

its a 280zx 1983 turbo coupe

Thank you

 

1200 would be normal for a cold idle. Does it come down after a minute?

The AAC and Air Regulator control the idle on the turbo. Check them. Also make sure you've downloaded the FSM from XenonS130 - S130 Reference

 

nope it never comes down at all..

and i just remembered if i leave the ac on and im not moving (sometimes if im driving at about 10-15 mph sometimes at around 50mph) the car revs a few times on its own.. i turn off the ac for a few minutes and turn it back on again the revving stops until the car stops (lets say on a traffic signal it revs when the car is at a complete stop on its own)

thats no way near normal right?

 

not sure if this is related or will help, not sure if they have a TPS? my 1984 300zx did everything youre explaining, even when releasing foot from gas pedla it would rev an additional 500-800rpms (when shifting) turns out my TPS was hooked up wrong, as soon as I changed the wiring, the idle went from 1300-1400 and dropped to 700-800 and the car no longer revs by itself.

 

hmm.. i'd give it a try i hope that really is the problem xD

Thank you

 

#1: Check timing.
#2: Check for vacuum leaks.
#3: Check that your a/c vacuum line is running to the vacuum tank, not intake manifold.
#4: Check AAC.
#5: Check Air Regulator.
#6: Check EFI grounds on intake manifold.
#7: Check ecu plugs for corrosion.
#8: Check CHTS and AFM plugs for corrosion.