PIP5189B

Bulletin No.: PIP5189B
Date: Apr-2016
Subject:
Black Smoke On Cold Start
Models:
2015-2016 Cadillac Escalade
2016 Cadillac CTS-V
2016 Chevrolet Camaro
2014-2016 Chevrolet Corvette, Silverado
2014-2016 GMC Sierra
2015-2016 GMC Yukon / XL
2015-2016 Chevrolet Tahoe, Suburban
With engines 4.3L, 5.3L, 6.2L L83, L86, LT1, LT4, LV3
This PI was superseded to update Models and Years. Please discard PIP5189A.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern
With the introduction of direct fuel injection systems, GM has revised the cold start control system to reduce cold start emissions.
Quicker catalytic converter heating helps meet the ever changing emission requirements and improve fuel economy.
Recommendation/Instructions
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 split injection strategy lasts for about 60 seconds on cold start.
This process may cause the customer to see increased black smoke, soot, during cold start andshould be considered normal.
The use of TOP TIER fuels lessens the effects during dual 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.
Please follow this diagnostic or repair 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.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may
occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools,
safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that
your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
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