18NA115

File in Section:
Service Bulletin
-
Bulletin No.:
18-NA-115
Date:
April, 2018
TECHNICAL
Subject:
Cold Start Misfire and/or Rough Idle – DTC P0300 May Be Set
This Bulletin replaces PIP4959G. Please discard PIP4959G.
Brand:
Model:
Model Year:
VIN:
From
To
From
Engine:
Transmission:
To
Buick
Enclave
2009
2017
3.6L LLT
Buick
LaCrosse
Allure
2009
2009
2016
2009
3.0 LF1, LFW,
3.6 LFX, LLT
Cadillac
ATS
2013
2018
3.6 LFX, LF4
Cadillac
CTS
2010
2018
3.0 LF1, LFW,
3.6 LF3, LFX,
LLT. LGX
Cadillac
SRX
2010
2016
2.8 LAU, 3.0
LF1, LFW, 3.6
LFX, LLT
Cadillac
XTS
2013
2018
3.6 LF3, LFX
Chevrolet
Camaro
2010
2018
3.6 LFX,
LLT. LGX
Chevrolet
Caprice PPV
2012
2017
Chevrolet
Captiva
Sport
2012
2015
Chevrolet
Colorado
2015
2018
3.6 LFX, LGZ
All
3.6 LFX
All
3.0 LF1, LFW
Chevrolet
Equinox
2010
2017
3.0 LF1, LFW,
3.6 LFX, LLT
Chevrolet
Impala
2012
2018
3.6 LFX
Chevrolet
Traverse
2009
2018
3.6 LLT, LFY
GMC
Acadia
2007
2017
3.6 LLT
GMC
Canyon
2015
2016
3.6 LFX
GMC
Terrain
2010
2017
3.0 LF1, LFW,
3.6 LFX, LLT
Involved Region or Country
North America and N.A. Export Regions
Condition
Some customers may comment that during a cold start, the engine will misfire and/or
have a rough idle and the Malfunction Indicator Lamp (MIL) may be illuminated. They
may also comment that the condition goes away after the engine warms up. The
technician may observe on a scan tool DTC P0300 (Engine Misfire Detected) set in the
K20 Engine Control Module.
Copyright 2018 General Motors LLC. All Rights Reserved.
Page 2
April, 2018
Bulletin No.: 18-NA-115
Cause
Possible engine cylinder block porosity causing a pinhole at the liner to deck face casting
area, allowing engine coolant to leak into the affected cylinder. The technician may
observe on a scan tool DTC P0300 Engine Misfire Detected set in the K20 Engine
Control Module.
Correction
Inspect for the cause of this condition by performing the Service Procedure below.
Service Procedure
Notice: A black light looks dark purple, but most of
the light it emits is in the ultraviolet (UV) range of
the spectrum, which is invisible to the human eye.
Under a UV light, white clothes glow in the dark and
many fluorescent colored items (e.g., coolant dye)
will emit a bright glow.
1. A misfire on cold start up only and/or a rough idle
with medium to high misfire counts, always
occurring on one or two cylinders, with the
condition going away after the engine warms up
can be suspect for coolant entry at the liner to deck
face casting. To inspect for the location of the
possible cause of the condition, add coolant dye to
the engine cooling system.
2. Run the engine through a complete operating
temperature warm up (the thermostat should be
fully open at 225°F (107°C).
3. Pressurize the cooling system on a cold soak
engine (after being warmed up to operating
temperature).
4. Inspect the suspect cylinder(s) with a blacklight
borescope for evidence of the coolant dye.
5. It may be difficult to see the actual source (e.g., a
pin hole) but the leaking coolant will usually stream
down the liner so that it can be seen with a
borescope. Do not confuse residual fuel on the
piston crown/surface as engine coolant.
⇒ If the borescope inspection is inconclusive, it
may be necessary to remove the cylinder head
for further visual inspection.
Notice: Small surface pock marks or pitting
appearance on the deck surface is normal and an
engine should not be replaced for any such
appearance marks as they do not connect to the
engine coolant passages and cause a leak path that
will generate engine misfires.
6. With the cylinder head removed, perform a visual
inspection. Reference the following pictures
provided. The first two pictures represent normal
examples of deck pitting and are not the cause of
the misfire and/or rough idle condition.
3632858
3632860
7. The two following pictures represent an example
and the location of how actual engine cylinder
block porosity appears. This would be a cause of
the condition.
Bulletin No.: 18-NA-115
April, 2018
Page 3
Notice: This porosity condition is rare, therefore
the technician should inspect the suspect
cylinder(s) and look for a break/pinhole in the
carbon ring area.
Shown at the deck face to cylinder liner interface
location is an area of engine cylinder block porosity
that has caused an engine coolant leak path into
the cylinder causing medium to high misfire counts
when the engine is cold.
⇒ If this condition is verified, the engine must be
replaced.
Dealers Required to Contact PQC should refer to:
#16-NA-338: PQC Assembly Replacement Process Dealers Required to Contact PQC Prior to Replacing an
Assembly in SI and reference this Corporate Bulletin.
Warranty Information
For vehicles repaired under warranty use:
3632865
Labor
Operation
Description
Labor Time
4067490
Engine Replacement
Use Published
Labor
Operation Time
3632864
Version Information
Version
1
Modified
Released April 13, 2018
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.
WE SUPPORT VOLUNTARY
TECHNICIAN
CERTIFICATION