Topic: Leaking Intake Gasket TSB

[Main One]

My 03 seems to have a leak into the intake manifold when I start her up on cold mornings - goes away in a couple of minutes after the engine starts to heat up.  After doing a bit of online research, the symptoms described in this TSB seem to match what I'm seeing.  I'm not getting any codes set, but that could well be due to my custom tuning.  In my case, the engine idles fast, and during that time with HPTuners' Scanner I can see that the MAF is reading extremely low, and the throttle body is much more closed than when she is idling normally.  After about 2 minutes (if just left idling) the engine sputters, and I can see after that on the computer that the MAF readings start coming up and the throttle starts opening up towards its normal idle position, 11-13% or so.  I guess that sputter is when the gasket starts to seal again upon heating up, and the computer has to back off of the idle airflow trims that it has been using to try to keep the idle speed in check. Looks like I'll be replacing my manifold gasket.

TSB:

#PIP3232B: Cold Engine Idle Misfire Or DTCs P0171 P0174 - keywords 4.8 5.3 6.0 air cold crack hesitate idle intermittent internal intake leak lean misfire miss P0171 P0174 P0300 power rough surge vacuum - (Feb 7, 2007)

Subject: Cold Engine Idle Misfire or DTCs P0171 P0174


Models: 2002-2005 Cadillac Escalade

 1999-2005 Chevrolet Avalanche, Express, Silverado, Suburban, Tahoe, Trailblazer

 1999-2005 GMC Savana, Sierra, Yukon

 2003-2005 Hummer H2



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Condition/Concern:
99 through 05 GEN III truck engines may experience any of the following:

A cold rough idle that diminishes as the engine warms up.
Possible DTCS P0171, P0174, or P0300.
Random misfires at idle.
Recommendation/Instructions:
The intake gasket seals may be leaking around the intake ports, causing a lean condition. The intake gasket seals may leak around the bottom side of the port, making it a challenge to detect the vacuum leak. The technician may also notice lower than normal MAF readings if the intake seals are leaking.

If leaking intake gasket seals are found, replace the intake gaskets. During the repair be sure to use the current GMSPO part number for replacement intake gaskets. The current GMSPO part number for intake gaskets will have a teal green intake gasket seal. The old version of the intake gaskets were orange in color. Use only the teal green colored gaskets for a repair.
The intake plenum should also be checked for excessive 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. Service Information states, "An intake manifold with warpage in excess of 3 mm (0.118 in) over a 200 mm (7.87 in) area should be replaced". Intake warpage is measured at the gasket sealing surfaces, and should be measured within a 200 mm (7.87 in) area. This measurement is across only two of the intake runner port openings. Measurements taken across the entire distance of all four intake runner ports will lead to unnecessary manifold replacements.

[MyBigToy]

What, you don't think they will replace yours under the TSB? With only 230k miles on it? 

[Main One]

What, you don't think they will replace yours under the TSB? With only 230k miles on it? 

Well, maybe at 230K, but its got 244K now.