Technical Service Bulletin PIP5069A — 2011 GMC YUKON DENALI

This Preliminary Information communication provides information to the technician about vehicles that have a lack of power on initial acceleration from a stop when the ambient temperature is approximately 103 Fahrenheit or greater and may include engine detonation or pre-ignition type events as temperatures approach 120 Fahrenheit. Technician will need to perform published Service Information diagnosis first. If Service Information diagnosis does not isolate the cause of this concern, take a Tech 2 snapshot of the concern happening and note the Spark Parameter in the Ignition Data List. If it drops near/below 0 degrees during the concern, check if there is a cylinder that shows any knock. If there is a knock in any cylinder perform a top engine clean. If the concern is still present, then switching to premium fuel (91 octane or higher) with detergents (Top tier fuel) when ambient temperatures exceed 110 Fahrenheit degrees, this should provide a slight improvement in engine performance when ambient temperatures are high especially as temperatures approach 120 Fahrenheit degrees.