So my swap has been running good usdm ej20, and recently the IACV went bad so I replaced it and it began to idle better, but now i'm having a different issue. My idle at a stop is at like 1000-1200 and when i'm driving around the revs jump when I shift it does not do it constantly but sometimes, i'll shift at 3000 and I release throttle depress clutch it jumps to 4000 like i'm rev matching. I don't know what could be the culprit any ideas? I have a stock sti BOV so it's not that. IACV is new so hopefully it's not that. bad tps maybe? Only code being thrown is P0507...

dam i sound stupid when i ask this... but what is IACV

Idle Air Control Valve.

Sounds like you have a vacuum leak somewhere.

Jay

guess i'm going to have to look for a leak, anyone know some common locations of leaks? I know i tightend down the TMIC on both the TB and the Turbo to make sure there was no leak there. Could loose uppipe or exhaust leak be the cause? I know I havnt had a chance to check the torque of the bolts again since i've been driving for a bit?

make sure throttle cable is loose enough, if its tight when the car heats up it will cause rpm's to raise rapidly.

i just adjusted that last night and it still does it, I am starting to get the darn IACV code again (1507) but the IACV is new I wonder if i need a new throttle body? I can't seem to find a vaccum leak anywhere, the only issues i'm having is the two code P0507 P1507 and my car idles at 1k i get random jumps in RPMS when shifting, could my exedy LW flywheel cause the jump in rpm?

bump,

still having this issue, just replaced the Neutral safety switch and still having P1507, what the heck is going on, this is drving me crazy.

Are you letting off of the gas while youre shifting? JK.

What if you remove the electrical portion from the IAC (mark its position) and try again. The ECU will still be sending a signal to the coil but the IAC itself obviously wont be moving. After starting the car turn it by hand to rough adjust the idle then take it for a test drive.

didnt know i could do that, the electrical portion of the IAC looks like it uses a special tool similar to a torx, and i don't know what type of tool it is, and i thought the ECU set the idle and you shouldnt mess with it....

I have not personally messed with the 02 WRX IAC but if its anything like the other IAC its just a valve actuated magnetically.

The ECU does set the idle but if you removed the top of the IAC then you can turn the valve by hand. Perhaps someone with more experience specific to the WRX can double check my suggestion.

i thought our cars rev VERY slightly when you press the clutch in to help with knock or something like that....

i thought our cars rev VERY slightly when you press the clutch in to help with knock or something like that....


i swore it raised a little due to the recirc of the by pass valve air going through the intake....

cuz mine does it as well...