Idler Air Control Valve

[aukster]

Ok I have a 2001 Olds Sihouette and I am pretty sure my IAC Vavle is gone bad or going bad. Was going down the road and it just shut down on me. Have had times when it would idle real high. From reading previous posts, this is what I think is wrong. I am going to replace it myself nad just need a little help. Where is it on the throttle body? I seen where it is to the right of the throttle body, but I am not for sure. Does anybody have a engine diagram for this or know where on the net I can find a picture or a how to guide to walk me through this? Also one more question. It seems like I am not getting good gas mileage. I was wonder what the tach should read when running 70mph on the interstate. Mine is running around 3100-3200 rpms at that operating speed. Thanks..

[jdl]

The iac is located in the picture. With the throttle open, the iac is bypassed. If the vehicle died on you going down the highway, open throttle, The iac isn't the problem, just my opinion. Those rpms sound too high to me, do you have it in OD?

[aukster]

Yes the car is in OD. Also, I was going down hill in the highway with my foot off the throttle. I think the tranny is going bad on me. but I am more concerned about the dying issue right now.

[LMP]

At 70mph, rpm should be below 2000. THe shift lever might be on OD but at this rpm, the transmission is not in 4th and TCC is not engaged. THis looks like a TPS failure , not IAC, and the cruise control is probably inoperative too.
www.avigex.ca/xport/dtc21.jpg

[aukster]

Now when this happened, I did have the cruise control on going down a slight hill. I just figured the going down hill, the cruise backed off and thats when it idled down. With what you said, Could it be this TP Sensor? If so, can I replace this myself or is this something that would need to be done in shop? I just figured that my tranny was going out, it takes spells of hard shifting and "Whining" when driving. Thanks.

Originally Posted by LMP

At 70mph, rpm should be below 2000. THe shift lever might be on OD but at this rpm, the transmission is not in 4th and TCC is not engaged. THis looks like a TPS failure , not IAC, and the cruise control is probably inoperative too.
www.avigex.ca/xport/dtc21.jpg

[LMP]

TPS is the likely culprit.

[merc81]

Originally Posted by LMP

TPS is the likely culprit.

I don't think so. I've had several of these vans begin to stall at random times, mostly when driving down the road during times of coasting, or no acceleration. Sometimes they stalled at idle, but generally it was while driving.
In each case, replacing the upstream O2 sensor was the fix. I have owned three vans, and all three did this.

[LMP]

I like this hindsight and take notice for the future but 02 sensor failure does not inhibit 4th gear/TCC/cruise. TPS does.