Answer

#04-06-04-040: Idle Instability, Low or Rough Idle with Electronic Throttle Control (Clean Throttle Body) - (Jun 14, 2004)

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Subject:

Idle Instability, Low or Rough Idle with Electronic Throttle Control (Clean Throttle Body)

Models:

2002-2003 Cadillac Escalade, Escalade EXT

2000-2003 Chevrolet Silverado, Suburban, Tahoe

2002-2003 Chevrolet Avalanche

2000-2003 GMC Sierra, Yukon, Yukon XL

2003 Hummer H2

with 4.8L, 5.3L or 6.0L V8 Engine (VINs V, T, Z, N, U - RPOs LR4, LM7, L59, LQ9, LQ4)

and Electronic Throttle Control

 

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Condition

Some owners may comment on an idle instability, low idle speed or rough idle.

Cause

Condition may be caused by deposits in the throttle body bore.

Correction

Clean throttle body bore and throttle valve plate of carbon using a shop rag and an appropriate cleaner. Refer to Engine Controls Repair Procedures - Throttle Body Cleaning Procedure. This procedure may be performed at any mileage necessary. Check to determine if the PCM calibration has been previously updated to one that includes the update for throttle body coking. For 2003 model year vehicles, look in the operating system portion of the calibration. For 2000-2002 model year vehicles, look in the engine portion of the calibration. If not, then update the PCM calibration to the latest calibration.

Expert:	Dan
Pos. Feedback:	99.0 %
Accepts:
Answered:	4/26/2009

Auto Technician

GM Mark of Excellence/ Service Guild Participant with 13 years experience, ASE Master Certified