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Document ID# 1565073
2003 HUMMER
H2 </TD>
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<H1>99-03 GEN III Engine Misfire at Idle Cold and Possible P0171 and/or P0174
-kw 4.8 5.3 6.0 LR4 LM4 LM7 LQ4 crack air hesitate intermittent internal intake
leak lean miss power rough surge vacuum P0300 #PIP3232 - (Nov 15,
2004)</H1>99-03 GEN III Engine Misfire at Idle Cold and Possible P0171 and/or
P0174
.</P>
The following diagnosis might be helpful if the vehicle exhibits the symptom
described in the PI.</P><A name=ss1-1565073><A
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<H5>Condition/Concern:</A></H5>
99 through 03 GEN III truck engines may experience any of the following: </P>
- <LI type=1>A cold rough idle that diminishes as the engine warms up.
<LI type=1>Possible DTCs P0171, P0174, or P0300.
<LI type=1>Random misfires at idle. </LI>
<A name=ss2-1565073><A
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<H5>Recommendation/Instructions:</A></H5>
Check for leaking intake manifold seals around the intake ports. The intake
gasket seals may be leaking around the intake ports, causing a lean condition.
Many times they will leak around the bottom side of the port, making it a
challenge to detect the vacuum leak. The technician may also note lower than
normal MAF readings if the seals are leaking around the ports. If leaking intake
gasket seals are found, they should be replaced. The intake plenum should also
be checked for warpage that may cause an uneven clamping pressure of the seal.
If the plenum is found to be warped, it will need to be replaced with new seals.
Intake Manifold Cylinder Head Deck Flatness specifications are located in SI.
</P>
.</P>
Please follow this diagnosis 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. If these steps do not resolve the condition,
please contact GM TAC for further diagnostic assistance.</P><A
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<H5>Models:</A></H5>
(99 00 01 02 03 C1 C2 C3 K1 K2 K3 LR4 LM4 LM7 LQ4 LQ9 Chevrolet Silverado
Tahoe Suburban Avalanche Express Trailblazer ) and (99 00 01 02 03 C1 C2 C3 K1
K2 K3 LR4 LM4 LM7 LQ4 LQ9 GMC Sierra Savana Yukon Denalli Envoy) and (02 03 K6
K7 K8 Cadillac Escalade) and (03 Hummer N2) </P>
.</P>
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<TD align=left width=778><FONT size=1>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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Document ID# 1565073
2003 HUMMER
H2 </TD>
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11-30-2005, 01:32 AM
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