PI1223
Service Bulletin Details
Public Details for: PI1223
Summary to be provided on a future date.
- 9999 -
Models from 9999
9999 GMC GENERAL MOTORS |
File in Section: Service Bulletin Bulletin No.: Date: PI1223 April, 2014 PRELIMINARY INFORMATION Subject: Black Smoke and Rough Idle on Cold Start Models: 2011-2014 Buick Regal 2012-2014 Buick Verano 2013-2014 Cadillac ATS 2014 Cadillac CTS Sedan 2010-2014 Chevrolet Captiva, Equinox 2013-2014 Chevrolet Malibu 2014 Chevrolet Impala 2010-2014 GMC Terrain Equipped with Engine RPOs LAF, LEA, LCV, LTG or LKW Condition/Concern Some customers may comment on black smoke, rough idle and minimal misfires on start up only. This can be caused by the introduction of direct fuel injection systems. Recommendation/Instructions A split-pulse injection strategy is utilized during engine cold start to reduce the time required to bring the catalytic converter up to operating temperature. This split injection strategy lasts for about 20 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. To verify that the split-pulse injection is causing the roughness or misfires with no codes set, you should watch injector pulse width with the scan tool during the concern. When in split pulse injector mode operation, the pulse width is about 50% more than a normal idle. If after 20 seconds the pulse width of the injectors reduces and the engine idle smooths out, this is considered normal operation and no repairs should be attempted. If the pulse width on the injectors drops by about 50% and the engine then smooths out, this is considered normal operation and no repairs should be attempted. The use of TOP TIER fuels lessens the rough idle condition effects during split pulse injection by reducing the amount of carbon on valve train components and a more complete combustion leading to cleaner burn. This cold start strategy is enabled upon start up after the engine has soaked for sufficient time such that the catalytic converter requires rapid reactivation.