| Subject: | Smoke, Fuel Knock, Surging and High Injector Balance Rates |
| Models: | 2004-2005 Chevrolet Silverado 2500HD, 3500 |
| 2004-2005 GMC Sierra 2500 HD, 3500 |
| 2004-2005 Chevrolet Kodiak |
| Equipped with 6.6L Diesel Engine (VIN 2 - RPO LLY) |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Customer concern may be a low speed surge (8 to 10 mph or near 1000 RPM), acceleration fuel knock noise at 1700 to 1800 RPM, rough idle, white smoke at idle or high positive injector balance rates.
Recommendation/Instructions:
- High positive injector balance rates (over +4.0 in park or +6.0 in drive) may be causing white smoke at idle or while driving.
- Document all injector cylinder balance rates at the beginning of the diagnosis.
- There is an updated calibration to address the white smoke, high positive balance rates, idle surge, and a fuel knock noise at or near 1700 to 1800 RPM.
- Install the updated calibration and evaluate the smoking, high injector balance rates, idle surge, and fuel knock noises.
- If there is still a mechanical concern with an injector, and balance rates are still over the SI specification of +4.0 in park or +6.0 in drive, replace only the effected injector.
Note: Before any injector replacement, a large fuel sample should be taken from the fuel filter and checked for contaminants or poor quality.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
