MattNuge

Okay, this is the lingering problem that I can't figure out after my engine swap in my 98 4Runner (3.4L V6 4X4).

Everything works great and runs smooth, except I run a very high idle speed. Upon start up, I idle around 1100-1200 RPMs, once I get warmed up, I run at around 1700 RPMs. FSM says I need to be at around 750 RPM at idle.

I re-checked the hoses, sprayed choke cleaner in the throttle body, clean the MAF, still nothing, I'm still at 1700 RPM. I'm tempted to just adjust the throttle screw but read in various forums that adjusting the screw is not recommended (hence why the screw is painted??)

Anyhow, any help would be appreciated. Other than that, I'm pretty happy with the swap, considering that's my only lagging problem. Practically runs brand new.

BajaRunner

There may be a problem with your Idle Air Control valve. Its right below the TB, and you can access it by removing the 4 TB bolts, and 3 hoses and 2 electronic plugs.

After taking it apart, you can see if its dirty or sticky. Most people complain about too low idle after *warm* starts.

Im sure MTL_4Runner will chime in soon though...

Adam F

There is no idle adjustment on the 3.4L V6.

Problem lies either in your IAC valve, vacuum leak, or a crack in your intake tubing.

ajitaw

any more insight on this? I have the exact same problem after my swap... it starts out fine but after I put it in drive and drive it for a bit and then put it back in park it idles at around 2000... any more ideas?

BajaRunner

Yep, it really does sound like your idle air control.

Writeup:
https://www.yotatech.com/forums/f123...ac-pics-92286/

mjwalfredo

I agree with SC. I tried to clean my IAC recently and when I put it back together, I used permatex to seal it back up which was a BAD idea. It got on the valve and caused it to stick open when the motor was warm giving me a high idle.

I opened it back up and cleaned up again and it idled normally afterwards. I suggest you do the same.

ajitaw

So the IAC could still be the culprit even if I start up fine hot or cold?

I guess there is no hurt in checking it out...

Ohio4R

I would say either the IAC or a vaccum leak.