Hi all,

recently (kinda) I rebuilt my b16a3 motor. During the rebuild I replaced the iacv due to idle surges. I thought that this would be the problem but after everything was said and done I still have the same idle surges as I did before. They do not start till the car comes to operating temp and they usually go between 100rpms to 1100 rpms. I have tried adjusting the dizzy but no luck. Any other suggestions? Thanks

 

Try replacing the ECT sensor.

 

I agree the ECT can cause some weird behaviors.

Question on your IACV, replaced with brand new OEM or a used part from salvage yard?

 

Brand new from Rock Auto

 

When I had a similar problem it was because my coolant system wasn't bled properly. The radiator fan needs to switch on at least twice while bleeding.

 

Interesting. I swapped the stock radiator with an aftermarket full size radiator. With this being said it seems the fans never kick on.

 

Bleed the radiator properly!

 

It will likely take much longer for the coolant to reach fan triggering temperature with a full size radiator. Especially if it's still cold out.

It's paramount for the fans to kick on though. For some reason it seems a couple of bubbles never gurgle out until the fans kick on.

 

Exactly. Even just replacing the IACV would allow air to enter the coolant system. This is what my idle looked like once warm:


I bled the coolant system again and let the fan switch on twice (previously only waited for it to switch on once) and the idle has been perfect ever since.

 

So far what I have found is that the idle problems are caused by as follows
vacuum leak
Dirty/busted IAC valve
Dirty/busted FITV valve
Clogged PCV valve
Bad intake manifold gasket