Technical Service Bulletins

I Hear Ya Knockin’

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I Hear Ya Knockin’

Some owners of 2007-2014 Cadillac Escalade vehicles may complain of an SES light on and a constant engine misfire. In some cases they may also note an engine tick/knock noise.

During diagnosis, the technician may find no compression on the misfiring cylinder(s), with 100% leakage into the crankcase. This may be the result of aftermarket ECM calibrations/components and detonation that lead to a melted piston. Note that this same bulletin applies to a number of other GM vehicles equipped with L76, L77, L83, L92, L94, L9H, LC9, LFA, LHB, LH8, LMG, LV3, LY2, LY5, LY6 or LZ1 engines.

1. If a lighted borescope is available, inspect the top of the related piston(s) through the spark plug hole to determine if any pistons are damaged/melted.

2. Inspect for aftermarket components such as an exhaust, ignition, high performance air cleaner or air intake system.

3. Determine if factory ECM calibration numbers and CVNs are present by following the latest version of 09-06-04-026.

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