Have a 97 mustang gt w/bbk cai & 70 mm throttle body. No other major mods. The idle one day is normal and the next at about 1700 rpm's. The past week is has been on the high side. Cleaned the maf, iac and still no improvement. Put a restricter on the iac, read somewhere that this might help and needless to say it did not. Any advice would help. Thanks in advance.

 

Im no mustang pro nor do i know the name of the part but the piece where you push to rev it up on the motor, i wanna say the throttle. Anyways spin that screw on it and see it drops it some, I spun mine up cause it wasnt getting enough rpms at idle so it wouldnt start all the time. Just be careful, i turned mine a lil to much and it was idling at 2,000 haha but now its at like 1000 so its good.

 

+1 check your idle set screw. get it running and just turn it down EVER so SLIGHTLY. it's very touchy.

 

I don't know if it'd be the idle set screw since it's not a constant high RPM, more or less an intermittent RPM jump..


Does it do it more when it's up to operating temperature than when it's cold??



JT

 

I would give the idle adjustment screw a shot first. I had trouble with mine as well, and that fixed it for me. The IAC mode that you are referring to, makes your RPM's drop faster after a rev.

 

+1 for adjusting screw...mine was revving up to 5k and staying, then i adjusted the screw a bit, then finally took it straight out