milesz

iTrader: (1)

Hey guys need some advice. I have a 2002 5.3 with a LS6 intake. The problem I am having is that when the car is in park, it idles fine but when I put it in gear the RPM goes up. It's getting so bad that I can be at a stop light with the car in drive, take my foot of the brake and he car will go to 10 mph to 20 mph to 30 mph without me touching the gas pedal. What could cause this? I have already replaced the throttle sensor and the air sensor with no change.

01ssreda4

iTrader: (96)

Is the car tuned for the 5.3?

LS6427

iTrader: (2)

Air is getting into the intake that shouldn't be.........its the ONLY way an engine can increase in rpm with the throttle blade closed.

Only way that can happen is the IAC valve is opening when it shouldn't or there's a vacuum leak.

PCM commands the IAC valve.....vacuum leaks are usually always there, not just while in park. So look into the IAC valve. And NO...not all PCM's will give you a code or an SES light until it totally fails.

Throttle bodies can also get real dirty and the blades could stay partially open with your foot off the pedal.....but again, it would be revving high in park as well as drive.

IAC valve is what I would change. If it doesn't work you can return it.

.

HAZ-Matt

iTrader: (8)

Since it idles well in park I would think it isn't exactly a real vacuum leak... but it could be.

The idle behavior being different between park and drive leads me to believe it is in fact related to the idle control parameters whether it be from poor idle airflow tuning, incorrect idle rpm table data, excessive idle / gear spark, or even changes in fueling between the cells from park to drive.

Alternatively, it could be a mechanical problem, but for idle to go up it would mean the IAC is opening more in gear, which it should not be commanding and seems odd if it were broken.

So what car is this in and what is the state of the tune?

ehksohset

iTrader: (1)

A failing TPS made my 01 Camaro idle high as well until I replaced it. Might be worth keeping in mind, too?

ls1ChevyStang

Have you ever figured this problem out?ifso could u plz help..sry for disturbing the old thread however just got my car going with the same setup and I have the same problem..

James Kunkel

Mine is doing the same thing.. put it in gear and it jumps to 3000 rpm. 2005 5.3 4l60e

James Kunkel

Mine is doing the same thing.. put it in gear and it jumps to 3000 rpm. 2005 5.3 4l60e PSI harness partial tune. New throttle body all new vacuum hoses. New injector o rings.

James Kunkel

Figured out what the problem was. Bad throttle body put my old one back on runs great