6.6 LLY Injector Knock, Heavy Smoke Suring Warm Up Cycle - keywords idle leak misfire noise pop rough

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in the PI.

A customer may have a of concern of rough idle, fuel knock or smoke while driving, combustion leak type noise, or a misfire.

Inspect for signs of combustion leaking at the injector bore to injector sealing area. If there are signs of a combustion leak at the injector bore, the injector must be removed and inspected.

After an engine build date of 8-20-2004, the injector hold down bracket bolt torque specification was raised from 20 N/m (14.7 lb ft) to 30 N/m (22 lb ft). If the vehicle build date is before 8-20-2004, or the engine traceability number is before 486520, (found in GMVIS/Vehicle Component), remove all 8 injectors and inspect for a leaking injector copper seal. If there are signs of a copper seal leak, the injector will need to be replaced. Replace the remaining copper seals during the repair. The injector bores must be cleaned of all carbon and debris before reinstalling the injectors. Torque the injector hold down bolts to SI specifications of 30 N/m (22 lb ft).

Please follow this diagnosis 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.