Gen2 3SGE Idling problem - Take 2

[alliance_22]

Weird... today i turned the idling switch completely closed.... and the car was STILL IDLING at 900 RPM!!!!

WTF? I'm lost ... seriously

[alliance_22]

So any ideas guys? Idle switch full close and car idles at 900rpm

[slide86]

sounds like you have a problem with your IAC (idle air control) motor.
if you wound the screw all the way in and there is no difference it would suggest that the IAC id not compensating for anything. usually when you turn the A/C on the IAC will adjust the RPM and keep the engine running.

i would find the IAC (it should run a hose on either side of the throttle butterfly and be a smallish black box) im not too familiar with the 3S engines...so i dont know where its located.

anyways, blow air through the hoses and clean out the IAC and see if that improves things.

also, it might be a good idea to wind the screw that adjusts the throttle butterfly so that the idle is bumped up abit. this will prevent the stalling

[RWDboy]

Dunno about 2nd Gen 3S-GEs, but the Idle Vacuum Switching Valve (a.k.a I-VSV, or IAC/Idle Air Control) is usually located underneath the intake manifold.

[alliance_22]

you mean the small hose that runs from under the main intake? and connects to a metallic tube under the manafold?

[RWDboy]

Those sound more like the vacuum hoses for the power steering pump

[AndyTTR]

understanding how the system works will help you find the problem.

When the engine is idling, the throttle is closed = no air going into the engine = stall.
To stop this from happening a small amount of air must be allowed to pass the throttle to keep the engine ticking over. This is done by an idle speed control valve. On newer engines this valve is electronic and is controlled by the ECU. There shouldn't be a screw to adjust the idle speed at all.

When you use your air conditioner it puts extra load on the engine which can cause it to stall. To avoid this another valve is used to let more air into the engine (increasing the idle speed). This valve is usually called the A/C (idle-up) VSV. Cars with conversions usually have dramas with the air conditioning as the computer that runs the A/C might not be compatible with the new ECU. I have this problem and it sounds real similar to what you're experiencing. There is also a valve similar to the A/C VSV on the powersteering pump, although it is mechanically controlled rather than electronically.

There are other devices which run off the vacuum generated by the engine - being a JDM motor, your gen 2 will probly only have the charcoal cannister and MAP sensor. The MAP sensor should tap off the back of the intake manifold closest to the firewall - see if you can find it and check the condition of the hose? Check that the vacuum lines to the VSV for the cannister aren't backwards? They are the two rubber hoses that come out from the top of the throttle body.

If you're sure you've checked all the vacuum lines, then your best bet might be to get in touch with the guy who did the wiring and get his opinion - sounds like it might be caused by an electrical problem IMO. Stalling problems could also be caused by issues with the fuel injection and ignition system too...

[alliance_22]

Thanks for that info AndyTTR! It really helped me understand how this bloomin thing works, the hoses are not in perfect condition but they dont seem to have any leaks either. Might have to take the possibility that it may be an electrical problem.

Also noticed something strange.... if i left the car for the night and start it in the morning when the engine is cold.... after i crank it it idles at 900rpm.... but after a good 30min drive or so, and i turn it off for like 5 min, and restart the car, it idles at 1.5-2k rpm... really gets me with a big ?