Idle drops into the 400's when AC compressor kicks on - Chevy Truck Forum | GMC Truck Forum

**Denaliano** · 05-01-2009, 12:41 PM

Perhaps unrelated, but ever since I've had my BB tuned PCM in, i've noticed a considerable dip in my idle speed at a light, stop signs, anytime i'm idling in gear, with the brake applied.

Looking at my efilive log files i see a steady 540-560RPM idle, but when the AC compressor kicks on, it will drop to the low to mid 400's causing a brief but noticeable stumble. bbbbbbbbbbbbbb..buuuhblaaaaah...bbbbbbbbbbbbbb

For why?

**Toadster** · 05-01-2009, 01:09 PM

omg - can't you search?

**StanfordM_3** · 05-01-2009, 01:32 PM

Quote:

Originally Posted by Toadster

omg - can't you search?

**Denaliano** · 05-01-2009, 04:30 PM

Bump for ideas

**thunder550** · 05-01-2009, 04:36 PM

Sounds like either your idle RPM table or idle airflow table needs some work.

**Hit Man X** · 05-01-2009, 06:21 PM

Easy fix.

**HD Redneck** · 05-01-2009, 06:22 PM

Quote:

Originally Posted by Toadster

omg - can't you search?

**nick993** · 05-01-2009, 06:26 PM

unhook your battery, then hook it back up after a while. then start the truck and let it learn for a few minutes(it will be rough then start to idle better). then kick the a/c on and it will bog but dont give it gas, just let it learn. it worked for me. the last time i unhooked my battery, i just hooked it up and took off, forgot to let it learn and it started dying on me at lights.

05-01-2009, 06:40 PM

Sounds like you got a cam in there, bro...wanna race?

I've read about solutions similar to Nick's. I'd give that a shot. Otherwise you can leave the severed head of a horse in Justin's bed.

**nboylie** · 05-02-2009, 04:49 AM

Pull out that johnson rod and give it a good clean with some brake cleaner, re insert and lube up.