So I've noticed lately that my car has been jumping rpms when idling. I've narrowed it down to just when I'm idling and I have the a/c on. Will cleaning the throttle body solve this or do I need to get my IAC checked?

 

Mods? These cars don't have IAC valves. The computer just opens the throttle a little bit instead.

 

Just a cat back exhaust but that shouldn't effect anything

 

First is to clean the throttle body. If it's never been done it will be very dirty.

This is not uncommon with these cars.

 

What's the proper way to clean the throttle body? I've heard different things as far as what to be careful about.

 

In for results

 

Make sure the car hasn't been started in like 15 minutes. No key on, nothing.

Unhook negative side of battery and put safely aside. Unhook intake. Unhook also sensors and anything from throttle body. All bolts. Spray throttle body clean onto a towel, not the TB itself. Stay away from spraying any sensors.

Do not rotate the butterfly. Wipe off all soot and then Reverse.

There is a post on here if you have throttle body issues after install. Should be no problem.

 

I'm bringing this back because as I dive down into the E37 computer, I find more and more things I need to fix. Like this ******* mess. It is an adaptive idle table that adds or subtracts air with RPM error. And the 2.2 has ridiculous numbers stock. Like 2lbs per minute. Looks retarded:

 

So for kicks, today I 1: replaced the values in that table with the stock values from a 2.4L. I got retarded low idle (450rpm) and it would hunt for the idle badly. This was before the AC was even on. So scratch that. 2: Next I interpolated the 0s in the stock table and then halved the entire thing. This put my adaptive idle airflow at 1lb an hour, which is double my realistic idle airflow. This time my problem was a high idle. About 1000-1100rpm and it had hanging idle. Finally, I interpolated away all the zeros and left them alone.
MAGIC!
The car idles fine. It also didn't fluctuate RPMs when I turned on the AC. I don't understand why it has such high numbers, when a 7.0L V8 doesn't even need those kind of numbers, but that is what worked for me. I'd also like to add that I made the AC torque reduction table more uniform at lower RPM.



I am going to go for a drive and report back, then probably write a post about it on HP Tuners forum and add a link here in this post.

 

Does your L61 (RPM and AFR) idle weird when you turn on your A/C? Step inside.

Yeah this works. If you guys have a tuner, please feel free to link them to that thread.