So I've been working on this for a while and have some threads that touch on it but after trying a few things I wanna get a post on specifically this issue and see if I can get somewhere to go.

Thing is the car after reving will go to 1000rpm for a second then drop to normal 750rpm when put into neutral.
How should the IACV act when the throttle plate is open? Is the IACV also open or closed?
Could the throttle plate be sticking?

There are no vacuum leaks I can find.

The manifold has been swapped with an f23 (from an f22) and I am using an IACV adapter plate. The person who also did this that I am using for advice says that he doesnt have the issue. I'm gonna check out the throttle plate, but is there anything else I should try?
I'm also trying to understand exactly how the system works, I have the basic.

 

I think when the throttle is open, the IACV will close. IACV is only active when the idle control system is active - based on TPS.

Is your base idle adjusted correctly? If the base idle is off, then the IACV will react funny to the inputs that the system is programmed for.

You swapped manifolds, but you're using the type of IACV that's right for your engine and ECU?

 

Yeah, its the f22 iacv. It can be adjusted but the normal idle is 750 as it should be.

Its just that 1000rpm for a few seconds thats weird. Could it be resistance from air flowing? increase in air flow and so the throttle body cant shut as easily?

If the idle went real low when in neutral then id think it was the iacv not opening correctly. Or am I missing the way the iacv works?
I'm not having any other issues related to the IACV

 

The only way to know is to take off the air hose and open up the butterfly and look at it with your eyes. If it's dirty, spray it with some carb cleaner.

 

Ive cleaned it before-few times recently. Im curious if theres something im not seeing when i drive or if its all sensor related

I should add that with these bolt on mods my car has only gained power when in closed loop . I just swapped out the o2 sensor for a good one but when the car is in open loop theres no low end torque. Anything that could be related?

 

If the IACV isn't operating in it's sweet-spot, it's nothing that you can see by looking at the throttle body. That's the point of adjusting the idle with the IACV unplugged - the BASE idle of about 550rpm.

If the base idle is incorrect, the ECU will drive the IACV one way or another to get the operating idle that it wants. So the fact the engine seems to have the proper operating idle doesn't mean the base idle is correct.

 

Ok. I will try adjusting the idle. I have the factory manual that goes into that. thanks

 

Look at my thread about setting the base idle, in the DIY section.
If you don't mind checking & getting back, I'd appreciate anyone verifying whether 550rpm is correct for any given model-year. The only ones I know for sure are the cars I've owned, so you can help make that DIY thread a little bit more complete.

 

Sure thing. I just have to figure out how Ima do this cuz my ultragauge got smashed and now my obd2 reader for my computer isnt working right. I cant see the exact rpms, unless that first line on the rpm's is the ideal idle.
The factory manual says 550rpm +/- 50 on f22b1/2 so you are right. Ill check out your thread though. I was looking around for more references.

 

The bottom of the tach is funny, I think that first line is 500.