All:

I am having the rough idle problem with my 2007 H3 3.7. I have opened the intake and cleaned the throttle body, and it has helped. I would really like to remove the Idle Air Control valve and clean it manually. I have done this on earlier model GMs (80s and 90s) with great results. However, I am not sure where the IAC is on this H3 throttle body, or how to remove it for cleaning.

Any tips, hints, pictures, or suggestions would be greatly appreciated!

Thanks.

 

You just did. No IAC valve. The fly-by-wire throttle body is used to control the air for idle.

 

Try cleaning the MAF sensor...

 

How do you clean throttle body....

 

The MAF in the air tube is absolutely spotless. I am very fastidious about my air filters.

I cleaned the throttle body according to the TSB "GM Drive By Wire Throttle Body Cleaning and Relearn Procedure" published by NAPA and Etech. This basically consists of opening the intake system and wiping down the throttle plate and seat ring. That's all.


So, "old-timer question time". How does the air get past the throttle plate during idle on this system? The older GM throttle bodies had an IAC with a pintle that would push into or retract out of blowby channel to control the idle air flow. This pintle would eventually coke up and choke the idle time air flow, and you could clear it by removing it and scrubbing the pintle.
Idle Air Control Valve - YouTube (46 second IAC video)

What is controls the idle time air flow in the Drive By Wire H3 throttle body?

 

Everything goes to the PCM, in a whole, but is directly affected by the MAF as well... theres more to it than that... but thats why a dirty MAF sensor effects the idle so much... If it is indeed spotless, I would check the intake tube just in case... Is it a stock intake or aftermarket btw? any other mods, spark plugs changed? etc, etc...

Ill look later at the diagram of the TB to see if there's anything else to clean...

 

I have looked at well over two hundred GM truck MAFs. Rarely, and I mean like one or two, actually look "dirty". They foul and become less efficient when covered in nearly microscopic dust particles that create a film like condition insulating the sensor from pushing the correct voltage (temp) signal to the PCM. Clean it anyway with MAF cleaner by CRC. Follow the simple directions on the can, do NOT touch the MAF other than at the electrical connector end. Simple stuff first.

Your source for TB info is dated. H3s do not use EGR or IAC. EGR is replaced by VVT, and idle (air) is controlled through the TPS (Throttle Position Sensor) by the PCM.

The best procedure is to remove the TB after disconnecting it. If you leave it in place, always disconnect the TPS electric plug. When done cleaning, reconnect it, then with the intake in place start and allow to idle until the PCM regains a smooth idle (up to appx 10 minutes). Do NOT be in a hurry, rush this final step at your own risk.

 

actually there is;
no egr valve like we all came to love but a simplified orfice hidden ?on back of intake,that other small hose.
egr used to give me fits,no idle at all when stuck, fords.
we dont hear much here abt it, maybe nobody can find it!!
maybe it never goes bad bcause its so simple!

 

My 06 3.5l had a rough idle when it was cold, hot, in gear or out of gear. I ran a can of BG injector cleaner through the system and it seems to be back to idling smooth again. It was about $30 for the can through my mechanic but it did the trick.

 

Tom..... that is a PVC hose connected to the valve cover for venting blow by in the crank case back into the intake.

The inclusion of VVT on the exhaust camshaft side allows the Atlas series to meet emissions standards without the use of EGR, simplifying the engine design and also increases power for a broad power curve.

VVT for EGR effect: retards cam to allow some spent gasses (Exhaust) to remain in cylinders to cool the next firing cycle.