On initial startup it will idle at 3k rpm’s before dropping and surging around 1200-1900rpms. There is no CEL. I have verified there is no vacuum leaks, bled the coolant, I’ve replaced the iacv (twice just to make sure the first one wasn’t bad), I have also replaced: o2 sensor, map sensor, spark plugs, spark plug wires, fuel filter, coolant temp sensor. It has a skunk2 throttle body and intake manifold installed. I have also replaced the ecu because when I bought it, it had an ecu for an a/t when the car is manual. I have not had the ecu tuned but it was surging before I replaced the ecu. Any suggestions? With the iacv unplugged the idle no longer surges

 

Loosen the bolts on the iacv and stick a piece of gasket material in between the iacv and intake manifold. Open the idle adjustment screw.

Those iacv's are so temperamental.

 

okay so i tried that and the idle does stop surging but its still a little rough, especially when revving. Do you think a tune could fix it ?

 

It stops surging when the iacv is unplugged??


I had a similar issue turned out to be the gasket between my throttle body and intake. Wasn’t a bad gasket just the wrong one.

also for me personally skunk2 seems to always generate problems when using their throttle body’s.

 

yes it does stop surging when unplugged,
this gasket came with the throttle body but it is thick as hell so I think I will try a different one

 

I don’t think the thickness will affect that. Just check and make sure the gasket covers the ports.