When I let my car fully warm up, and I unplug the IACV to set the base idle, the car surges like crazy and I can't adjust the idle with the idle adjustment screw.

What would cause this type of problem?

All the vacuum hoses are new except for the PCV hose going from the IM to the PCV.

 

What is the idle behavior with the IACV connected? Is it high and hunting as well? If so, look for an intake air/vacuum leak and also bleed the cooling system.

 

It's high and surging up and down a few hundred RPM.

The intake manifold gasket is brand new, all brand new rubber water/heater hoses, all new vacuum hoses.

I have bled the coolant three times now.

 

Have you tried cleaning and adjusting the FITV?

 

I have tried that - thanks for the suggestion, though.

I have an FSM, and I've gone all the way through it.

 

Any CEL codes? Did you do electrical troubleshooting on the coolant temperature sensor, TPS, and MAP sensor?

It would also help to list all that you have tried thus far.

 

throttle body gasket? sound like you have a vacuum leak when you cover the throttle body with your hand does the engine die?

 

No CEL. I haven't done any other electrical troubleshooting yet.

I took off the intake manifold because I was replacing all the radiator/water hoses (even the tiny ones going to the IACV etc), including all the PCV hoses and breather chamber etc. and it was much easier to do with the IM off. I took the entire thing off as one unit and didn't touch or mess with the IACV, MAP, FITV etc.

As soon as I put the IM back on (with a new gasket, surfaces proper cleaned, and proper torque sequence), I've got the idle issue. Before hand, I had zero problems with this car!


When I cover the throttle body should the engine die? If it does not, does that mean I have a vacuum leak somewhere? I've never heard of this method for checking for leaks.