cold blodded burb

[acl]

Have 2001 suburban, 180k miles. starts just fine on cold days but then will die or chug. Runs well once it gets going. Also noticed a few days ago (2 times now) when i go through a auto car wash, rpms drop and rise a few times. Any clues???/ thanks

[Palf70Step]

Not really sure.

Thoughts are

Fuel filter dirty

Your distributor might have a crack in it and the moisture (car wash) causing it to fluctuate.

[Special-Ed]

how are the plugs and wires? you should be at your 2nd set of plugs and wires alreadfy....

check for water getting underhood and into map/maf sensor

also clean the throttle body around the butterfly

your cold chugging could be leaky injectors/fuel pump and an unprimed fuel rail at start up....

[acl]

checked plus and wires both good and less than 10 k since changed. researched a little about intake gasket shrinking with age and cold weather causing cold air imput and changing fuel mix?? ring any bells to anyone. Thanks

[buddy_1]

Yes it does, has it ever had gaskets replaced? The original gaskets had orange rubber. The new style gaskets have teal green rubber. Here is a copy of the actual bulletin with instructions on checking the manifold for warpage.

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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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This PI was superseded to update parts information. Please discard PIP3232A.


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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

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

 1. A cold rough idle that diminishes as the engine warms up.
 2. Possible DTCS P0171, P0174, or P0300.
 3. 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.

 1. 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.
 2. 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.

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Also, I would recommend checking the condition of the knock sensors and pigtail harness under the intake while you're there. They are bad about filling up with water and corroding up. Whether you replace them or not, use RTV when install the rubber caps to prevent it from happening in the future. Buddy

[acl]

Buddy 1 hit it on the head. Intake gasket leak. i had the bad code for a knock censor also, did not know if it was bad or gasket leak coding so i changed the knock censors while i was down that far already. thanks guys.