After seafoaming my car I had a rough idle with a random miss. Figured I needed to change the plugs, used NGK platinum, replaced manifold, throttle body, and valve cover gaskets, with new wires, and cleaned the inside of the intake and throttle body. Still had a low, surging rough idle. Read through the forums and decided to remove and clean the IACV. Took it apart, made sure it would spin freely, cleaned it and re-installed. Still a rough idle and now a SCREECHING sound coming from my throttle body. It's loud, and sounds almost like a belt slipping. It only stops when the idle surges really low.

Some info on the car. 1992 sc300 5 speed, factory. The seafoam I used was the kind in an aerosol can, with a tube to insert right at the mouth of the throttle body. So I figure it is possible the fluid came in contact with the TPS and IACV possibly clogging or damaging them.

When you take apart the valve, I noticed the length of the protruding spring tip that sets inside the manifold sits higher or lower depending on how you spin-orientate before reassembly. Does it matter where it is located before installing it?

Jdm motor might be sooner than later.... Any help would be appreciated! I have searched the forums and realize I need to grab a multimeter soon.

 

So I feel a little dumb, but it was an air leak from the throttle body. I guess I might have tweaked the mounting bracket near the mouth causing it to not seat correctly. After cleaning the gasket and carefully tightening it down the screeching/whistle sound was gone and the idle smoothed out.

 

the iacv will eventually work itself to the right position, but if you moved it it may take a few starts for it to get in the right spot again.

 

The IACV are somewhat tricky to get right. I actual hate mine..