My '03 Silverado runs and idles fine, around 700 rpm. I have cleaned the MAF thoroughly and it has a new ported TB. The only thing I have noticed lately though is that when I turn the A/C on, the idle stays the same. This makes it struggle just a bit at a dead stop, but its barely noticeable. I know when I turn the A/C on the idle is stupposed to go up a little, probably to around 1,000 rpm or just above. What exactly is it that tell the truck to raise the idle for the extra load? Is there a sensor somewhere that could be changed?

 

It's controlled in the tune.

 

Hmmm, I wonder if my ECU is on its way out or something because the tune is bone stock.

 

If the tune is dead stock then the idle isn't supposed to go up to 1000 with the AC on. From the tunes that I've seen, GM usually sets idle speed 50rpm higher than normal idle speed.

 

The stock Idle on an 03 should be around 650 RPM. It won't go up much if at all with the AC on.

It may be your Ported Throttle Body causing the issue.

 

Possibly. Its not too bad. If it only is supposed to go up that much then I won't worry about it. The A/C compressor is kind of on its way out anyway which may cause it to be a bit harder to turn.

When you do an idle re-learn, should you wait a certain amount of time before you turn on the A/C when its first started up after the battery has been unplugged? Could that make some difference?

 

Might need to tweak the idle portion of the tune after modifying the TB, I'm sure it has altered the idle airflow into the engine.

 

Mine is always stable.