This bulletin applies to all 2008-2019 GM passenger cars and light trucks equipped with direct fuel injection systems. Some customers may comment about black smoke, rough idle and minimal misfires on a cold start, and the MIL may not be illuminated.
With the introduction of direct fuel injection, GM has revised the cold start control system to reduce cold-start emissions. Quicker catalytic converter heating helps meet the ever-changing emissions requirements and improve fuel economy.
According to GM, a dual-pulse injection strategy is utilized during engine cold start to reduce the time required to bring the catalytic converter up to operating temperature. This dual-pulse injection strategy lasts for about 60 seconds on cold start. This process will cause the customer to see increased black smoke, soot, rough idle or minimal misfires during cold start and “should be considered normal.”
About the Author
Information courtesy of Mitchell 1
Information for Technical Service Bulletins comes from ProDemand, Mitchell 1's auto repair information software for domestic and import vehicles. Headquartered in San Diego, Mitchell 1 has provided quality repair information solutions to the automotive industry since 1918.
Mike Mavrigian
Motor Age Editor
Mike Mavrigian has written thousands of automotive technical magazine articles involving a variety of specialties, from engine building to wheel alignment, and has authored more than a dozen books that crisscross the automotive spectrum. Mike operates Birchwood Automotive, an Ohio shop that builds custom engines and performs vintage vehicle restorations. The shop also features a professional photo studio to document projects and to create images for articles and books.