IAC issue VX II V6 3.8

[kais3r]

Hi guys, got an issue with a new IAC I've installed, it will idle normal but the initial engine startup position it's using is pushing the revs to 1300-1400RPM with the base idle completely shut, then drops back down to normal over about 2-3 seconds.
Don't think this was normal, would prefer it to be around 775 with a cold engine as this is meant to be peak idle RPM, and from there the PCM can adjust the idle to suit current temp conditions like raising idle for a cold engine.

Question is, how could I adjust it so it's what I'm after and can it be done without a tech 2 tool?
I'll adjust base idle to correct setting again once I know how to get the IAC sorted.

Thanks

 

[devilly]

you could just adjust the accelerator cable, mark it first in case you want to change it back
could also be the tps = throttle position sensor

 

[lowandslow]

Didn't forget to re fit the o ring on the IAC or is the o ring damaged? This can cause a vac leak which could be the cause of your dramas.

 

[kais3r]

The cable is already in a position where the throttle is fully closed and the revs are too high. All the air is coming through the IAC so I need a way to adjust its position during ignition on prior to starting.

 

[kais3r]

No the O-ring is fine and there's no vac leaks, it idles fine at the right RPM, just need the start up position of the IAC to be changed to a more closed state so the engine doesn't rev so high in the beginning.

 

[PRAVX II S]

The IAC is controlled by the ECU, There are numerese sensors on the engine that communicates with the ECU. Then the ECU will make appropiate adjustments to the IAC.
From memory you can see if the IAC is working with a Tech2 you can control the motor. But this is more for diagnosing.
Are you sure you have no air leaks?

 

[Pollushon]

Mine behaves the same way on its first cold start and I have no leaks and no issues, not to say you don't but I've found a lot comes down to where you got the IAC from and what type of tip it has.

The ECU tends to just dump, retard and open its throat on cold starts, til it can safely settle on idle speed.

Are you saying it does this on every start not just dead cold?

 

[kais3r]

Yeah it does it on hot starts too, didn't do this before, it always used to start up around normal idle or a little higher and have very little adjusting to proper idle.

Had no issues preventing engine startup by closing the base idle with the old IAC installed, so this would indicate no vac leaks, I have checked for them anyway.

 

[lowandslow]

The IAC should self set itself after a key cycle.

Are you sure the plunger on the end of your new IAC is the same shape as the old one?

 

[kais3r]

If this helps, the Pintle is 19mm out during ignition on, from the nearest part of the housing to the tip.