I have finally found out what the IAC is, but I have no idea where it is or what it does. I have done searches and seen that it is linked to a few problems I am having with my car. Any info on location or maintainence on the IAC is appreciated. Thanks!

 

The IAC is located in your throttlebody, just below the TPS, If you are looking at your engine by standing in front of the car, it is on the left side, on the bottom, there are 4 wires going to it. It looks like a large nut (about 1") with a plug on the end.

What is your car doing???

JOhn

 

John ,thanks for the help! I have this posted somewhere else, but here it is again!
I have a 1985 IROC and it has the following issues:

1)If the car is not started in a while it goes to shut off, and starts to backfire. I need to keep the car running with the pedal. This only happens if the car is not started often. When it is started often, the MAFS works fine, the idle shoots up, and then calms down.

2)While crusing, when the car shifts into 3rd, it doesnt hesitate, but it feels like it is puttering. Its not the motor, because if I give more gas, its fine. Is it the tranny mount?

3) Can I do anything to add power? Is a 350 crate motor recomended? I am looking for 300hp. Can I obtain this with the 305 in the car? Will I need to do a full overhaul to achive it?

Any opinions, questions, or feedback is appreciated. This is my first post. Thank you!

 

Have you checked your base timing, sounds like it might be advanced to far.

 

I did the timing, but I did not unplug the ECM wire above the A/C resivour. Should I redo the timing and unplug that wire? What is the procedure for this?

Again, thanks for the help guys! Love the white with red stripes, That may come for me down the line!

 

Yes, unplug the ECM when you set your base timing so the ECM isn't f**king with it. Good ball park is 0-6*, drive it ,tweak it for best overall performance.

 

Good advise, I will let you know how it goes! What does the IAC do or affect? Do I need to clean this? Also, would the Oxygen sensor have anything to do with the way my car is running? As far as the car puttering, can that be the Tranny mount?

 

It can't hurt to clean those sensors, If you mess with them, make sure you adjust them. You can find the directions off this sites main page in the tech articles. If you have not look there, do yourself a favor and read them, tons of info, good stuff. As far as the tranny mounts, if they are not good and tight, tighten them.

 

THe IAC "Idle Air Control" is just that, it controls the "Idle Air" for your engine. Basically the computer si subposed to adjust the IAC to compensate for load, thru the IAC, such as putting the car into drive, turning on the A/C etc. How our system works is there is a "Pintle" that is turned in and out by a small electric motor (the IAC) when the idle is too high, the computer turns in the pintle to lower the idle, if the idle is too low it pulls the pintle out to let more air in.

The O2 sensor could control that, unfortunately if your car does strange things on a cold start then it might not be the O2 sensor since the O2 sensor is only used when not in WOT and after the engine is warm. Before the engine is warm the computer is in Open loop. It sounds like your O2 sensor could need a change.

As for the Transmission shifting and then feeling boggy, welcome to the wonderful world of the 700R4, I find that my car if I am not getting on it will go into OD at 30 Mph or lower. It kind of sucks, I have not seriously tried to fix it, but I would personally like my car to only go into OD after 50 Mph...

Hope that helps

John

 

On the street I basiclly leave the car in drive! Will it still shift into OD? I am soo Tempted to rip everything out and get a new corvette crate motor and trans! That would probally bring more headaches though! Are the TPI's really rated as great engines? Also, what can I do to add about 50 to 100hp, naturally to the existing stock set up? Exhaust obviously. Heads? New intake?

 

AS for the timing procedure - be sure you disconnect the ECM wire, set the timing while the engine is warm, recheck it after tightening down the distributor (it's common for it to shift a gegree or two during the tightening), shut the car off, and disconnect the battery ground terminal for 5-10 minutes to clear the check engine light the timing setting procedure causes.