Dr_Shakalu

Hey everyone. Well, had a day off so I decided to install my injectors from FIC. I also had a code for high idle so I decided to clean my IAC. I took off the IAC and saw that it was gunky so I took some throttle body cleaner and sprayed it until it was clean. I didn't take off the throttle body to clean so I sprayed throttle body cleaner in the throttle body and the hole for the IAC. Put the IAC back on and swapped out my old injectors. It wasn't too bad, took just about an hour. When I started my car, the idle jumped up to about 2500-2800 rpm and stayed there even after the car was heated up. Put it in gear and the idle stays at 1500 rpms. Idle never came back down. Went and unplugged the connector for the IAC just to see if it would do anything and the rpms flew up to 2500 rpms again. Did I mess something up with the IAC or do you think I need a new one? I also found these 3 things sitting where the injectors go. Could these parts have fallen out of something while I has cleaning the IAC? Here's a picture of the things I found. Would have been great if the car ran well after installing the injectors and cleaning the IAC.

Tom400CFI

Go drive it over 30 mph. That should reset the IAC.

Dr_Shakalu

I didn't put it on my post but it's a 1996 coupe auto. The first thing I did was jump onto the highway. Went up to about 65mph but high idle problems were still there after getting off. I don't know if it matters but while on the highway I switched from drive to overdrive and the rpms dropped like normal. I just pulled out the IAC but I don't know what I'm actually looking for. I sprayed the unit and spring with throttle body cleaner earlier to clean it but I'm not sure if it's just broken. Is the spring supposed to compress when you push down on it from the pintel? I tried to push it down but it's stuck and nothing compresses. Does that mean the IAC is faulty? I just ordered a new IAC but it'll take a couple of days. Thanks Tom.

Tom400CFI

I'd replace the IAC at this point too. I don't believe that you're supposed to push in on the pintle. If you have access to a scan tool, you can see what your IAC counts are (pintle position) -or at least what the ECM is calling for. If a scan was showing a low number but your MAF G/sec are high and idle is high, that would pretty conclusively show that the IAC is toast.

You're sure you don't have any big vacuum leaks?

Dr_Shakalu

I'm almost positive I don't have a big vacuum leak. Before I did anything to the car, I did get a code P0507 high idle. That's the reason I decided to try and clean the IAC. The idle wasn't really high, just about 900 in gear. I wouldn't have even noticed if the engine light hadn't have gone on with the P0507. After todays test drive, with the rpm at about 2500, I did look for a vacuum leak but everything looked okay. I hope it's just the IAC. I also took off the TPS by accident thinking it was the IAC. It was a little dirty so I cleaned it and put it back. I just ordered a new IAC and TPS but my new question is how do you reset the IAC and do I need to reset the new TPS? I read that on some years the TPS is self adjusting. When is it going to end?!?!?

Tom400CFI

You "reset" the IAC by driving over 30 mph.

Your '96 should have a non-adjustable TPS...just put it on and your done.

Dr_Shakalu

Well, I took it up to 60 on my test drive but maybe I didn't drive it long enough. What about people saying to step on the gas, start it for 5 seconds, shut it off for 10 seconds and turn it back on. That's why I'm asking because some say it will reset after driving past 35 and others that it reset doing the on off routine. Hopefully it's a faulty IAC since I already have one ordered.

Cliff Harris

I answered this in the other thread you posted on this subject, but for the sake of thoroughness...

You should retract the pintle on the IAC before you install it. I did it by pushing it against the edge of my workbench with my leg. I couldn't press hard enough with my fingers. If the pintle is extended too far when you install it, it can bottom out and break the plastic guide it rides in.

A scan tool can be useful in a situation like this. I have heard that the IAC counts will go to zero if you have a vacuum leak. That makes sense because the ECM/PCM is trying to shut off the extra air. This would only apply in closed loop mode when the ECM/PCM is monitoring the AFR with the O2 sensor(s).

Tom400CFI

The ECM tries to control idle speed long before closed loop is achieved. It starts as soon as the key is turned on.

Dr_Shakalu

So what is the correct method of resetting the IAC? Is it drive it 35 mph and above? For how long? Or the gas pedal method? With the gas pedal method, 1st you step down a little on the gas, start it and wait 5 seconds but are you supposed to keep your foot down on the gas for the 5 seconds or step down on the gas pedal until it starts. Then turn it off. Then you're supposed to wait 10 seconds and restart. So which way is it supposed to be for my 96 coupe auto?

Tom400CFI

Yes. A few seconds should be sufficient. Long enough for the ECM to bottom the pintle. 5 seconds, maybe?

Never heard of the gas pedal method.

Dr_Shakalu

When I searched on this forum and on google, these 2 methods are what came up. Actually, the gas pedal method came up a lot more but it didn't say for what years.. I'm going to try both methods when my parts come in so hopefully it'll work.