IAC Problem

[TTA81]

Does the IAC Reset Procedure on gnttype.org refer to engines that are stock, modified or both?

The problem I have is that at park/idle, closed loop, engine at normal oper temp, the IAC count is at 00. The TPS is at .42 / 4.8 WOT. If I put it in gear, the IAC will go to about 05 then drop to 00. Is this normal for my mods (see sig)? The RPM at park/idle is about 950-1025, in gear about 850. Also, once the car is fully warmed up, the RPM s will fluctuate from about 1000-1150 until I put it in gear and stay steady around 850. Put it back in park and its back to fluctuating after about 30 seconds.

I tried to reset the IAC per gnttype.org but as I was turning the screw CCW to raise the count, it got up to about 03, rpms dropped and engine died. Of course the TPS changed also. So I just put it back to where it was. I don't know how else to get the desired 20-25 counts if the car won't stay running past 03 counts.

Also, when the car is started first thing in the morning, it will run for about 2 seconds and then die. On the second try it starts right up.

All sensors are new and about 5 months old. KDK Performance in Orlando did all the sensors and adjustments and has been running fine until about a week ago. Checked and replaced all vacuum hoses. All other Scanmaster readings are normal. Please help.

 

[87NAT]

Good rule of thumb to set a basline for the IAC is this. When standing on the drivers side looking at the TB...you should only see about 1 1/2 threads of the the set screw sticking out towards the radiator.

When setting the IAC do it with the engine warmed up. After you set the screw let the car run for 2 minutes..it will hunt for an idle and correct itself. Shut the car off and restart. You may have to do this a few times and reset the TPS as you go.

Have you pulled the IAC and checked to see if it has a bunch of carbon buildup on it? That could be an issue also.

 

[GRAY86T-TYPE]

OK, I have been having the same problems, and I finally fixed my car today after a month. I tried setting the IAC like you did, exactly how the website said to reset it (GNTTYPE.ORG). I also replaced all of my sensors and ever since I did this the car has not run right. It wouldn't start, stumbled in park, and had a crazy idle. I pulled my new IAC out, and heres what I did. I pulled the spring back and turned the head almost all the way down to shorten it. If its out over and inch it will create problems. I put it back in and, I was able to tune the sensor in pretty good by turning the screw on the side of the throttle body. Then all of a sudden I started having the same problems. Next I cleaned the old sensor really good and put it back in. Then I was able to tune the TPS and IAC where they needed to be, and the car has never run better. I drove the car all day, and kept shutting it, and restarting it. This fixed the problem, so if you kept the old IAC, clean it with carb cleaner and reinstall it. You can see that the new one was made cheaper than the AC Delco one. Now the car runs perfect!

 

[TTA81]

Thanks guys.

87NAT,
I did clean out the TB, but not the IAC. I'll pull that out and check it.

I'll try these things this week and see what happens. I'll keep you posted.

 

[GNVYUS 1]

Before you buy tons of parts and mess with the IAC, make sure you don't have any vacuum leaks. The more unmetered air that enters the lower the IAC counts will be, which altering the TPS, IAC itself or the set screw won't really fix.

Start with the lines coming off the vacuum block on the Throttle Body.

 

[TTA81]

Ok, Just bought a MityVac and will check again for vac leaks. Will keep you guys posted.

 

[Junior Samples]

I pulled my new IAC out, and heres what I did. I pulled the spring back and turned the head almost all the way down to shorten it. If its out over and inch it will create problems.

if over inch and 1/8 or right on, the pintle will bottom out.
When I replaced mine there was a little note in the box that described just that, so i went and messured from base to tip and sure enough, it was over the inch and 1/8

Pain in the ass holding back spring with paws then making sure the spring seats back into the notches but wala when done.

Mike