I've gotten my problem narrowed down to most likely being the IAC. Engine idles very low and wants to die in Reverse and Drive, until I hit the gas then it drives fine. Only while idling does it act weird. Hence me figuring it's the IAC. Can anyone give me some help finding it/instructing me how to replace it. I have the part already. This is the first car I'm doing my own work on and i don't have much experience so detailed help would be much appreciated.

2004 3.4 Automatic Monte Carlo

 

Different car, but similar 3400 (GM 3.4L) engine. The IAC is in the same location.

Here's a video: https://www.youtube.com/watch?v=ApKYaFDBAMk

 

Thank you! Will do it in a little bit. Hopefully this gets rid of my check engine light.

 

Another common problem with 3400 (3.4L) and 3100's (3.1L) is clogging of the EGR passage between the EGR valve and the throttle body. It gets clogged with carbon buildup. You might want to get scanned for trouble codes. Code P0401 is insufficient EGR system flow.

Here's a couple videos demonstrating how to clean it:

1.https://www.youtube.com/watch?v=hpB6CELWYhQ

2. https://www.youtube.com/watch?v=Ivhr...zx6ZMjwUCa-Opn

Hope this helps.
Please keep us posted.

 

Replaced the IAC. Still idles really rough especially when I put it in reverse after it's been heated up and driven for a while. Sounds like the engine wants to die and even squeaks as it bucks backwards. Check engine light is also on. I'll check the EGR tomorrow and hopefully that solves my problem.

 

Nice to see your working your way through your cars issues. What led you to end up believing the IAC was the issue? I have read your post that the replacement part failed to correct the issue. Sad...

Ay signs of a vacuum leak, cracked vacuum lines / connectors?
Have you by chance played with the MAF Air sensor to diagnose if it is faulty?

Read a couple of the below articles and maybe you can expand on them.


Troubleshooting Mass Air Flow (MAF) Sensors


FACTORS AFFECTING CALIBRATION
“False air” leaking through cracks in the ducting that connects the MAF to the throttle body is a common problem affecting MAF sensor calibration. In most cases, false air leaks will cause low-speed stalling or rough-idling complaints.

Contamination of a MAF’s *resistors is, by far, the leading cause of MAF calibration errors. Oil, dirt or even paper filaments detaching themselves from poor-quality air filters can accumulate on the metal-film resistors suspended in the intake air stream.

Number 2 article below...

See Bad Mass Airflow Sensor Symptoms on YouFixCars.com

 

Thank you for all the info! I actually have a whole new MAF on the way as well as a PCV valve and hose. I plan on getting those parts today. Will also be replacing spark plugs. I hope to have all that installed and the throttle body cleaned by next week. Will definitely keep updating.

 

I also just noticed that turning the heat/AC on or off makes it idle way lower than it was when the heat/AC was on. If that helps anyone here it will also help me. Lol

 

sounds like a power issue. have the battery checked, seems silly but alot of problems can be caused by a battery not providing the right voltage to the different parts. typically turning your a/c on and it wanting to die is a pretty good notation that you got a power issue going on.

Charge battery overnight and then take it to be tested. make sure they are testing cold cranking amps, and they are doing a load test.

The IAC (this is what you started with) would adjust the air flow for the vehicle during idle if it started dying, but this would only help if your air ratio was off, and you would only replace it if it did not adjust your air accordingly.

 

Step #1 before you go any further, have the check engine codes ran. See what those are. The car is trying to give you large hints to what's wrong.

Second, this is only a guess based on the age of the car and what sounds to be a power issue. Any idea when the spark plugs and wires were last changed? Those should be changed every 100K miles, you can probably stretch to 150K, but bottom line, after 100K miles, the plugs are going to start producing weaker spark and eventually lead to mis-fires, hesitation, feelings of stalling or actual stalling.

Plugs are cheap and easy. stay away from BOSCH plugs. AC Delco or NGK are my recommendations (I tend to buy from RockAuto.com and NGK platinum plugs are dirt cheap through Rock).