03 lean engine banks

[hotrodrado]

I have a 2003 silverado with a 5.3 and I get random lean engine codes. Sometimes its just one bank or the other but mostly both. I changed the O2 sensors but it didn't help. it seems the only time i get the codes is when the truck between 160 and 190 degrees. The truck will strart to idle rough almost like it has a larger cam, it never dies though. Any information you may have on this subject would be nice.

[ChevyTech007]

Sounds like intake gaskets. Heres a bulletin.

 

Subject: 1999-2005 GEN III Cold Engine Misfire at Idle with Possible P0171 and/or P0174 - keywords 4.8 5.3 6.0 air cold crack hesitate idle intermittent internal intake L59 LR4 LM4 LM7 LQ4 LQ9 P0300 #PIP3232A - (03/08/2005)

 

 

 

Models:

 

 

 

 

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

 

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:

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, replace the gaskets with the updated part number of 89017589. The updated replacement gaskets part number 89017589 are teal green in color. The teal green gaskets will replace the original orange color intake gaskets.

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.

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.

 

Models:

(1999-2005 Chevrolet Silverado) and (1999-2005 Chevrolet Tahoe) and (1999-2005 Chevrolet Suburban) and (2002-2005 Chevrolet Avalanche) and (1999-2005 Chevrolet Express) and (2002-2005 Chevrolet Trailblazer) and (1999-2005 GMC Sierra) and (1999-2005 GMC Savana) and (1999-2005 GMC Yukon) and (1999-2005 GMC Yukon XL) and (1999-2005 GMC Denali) and (2002-2005 Cadillac Escalade) and (2003-2005 Hummer H2) and (2003-2005 GMC Envoy) and (2004-2005 Buick Rainer)

[Mr. Smith]

I have a 2003 silverado with a 5.3 and I get random lean engine codes.  Sometimes its just one bank or the other but mostly both.  I changed the O2 sensors but it didn't help.  it seems the only time i get the codes is when the truck between 160 and 190 degrees.  The truck will strart to idle rough almost like it has a larger cam, it never dies though. Any information you may have on this subject would be nice.

 

<{POST_SNAPBACK}>

 

 

 

 

Intake gaskets are probably the culprit.

[smileyman57]

I have this exact problem and have determined that the intake gasket requires replacement per the tests outlined in the bulletin.

 

For those that have done this repair....

What is the torque spec on the bolts and do you put any loctite or sealant on the bolts. Also any other issue to be concerned about before digging in.

 

Thanks

[Mr. Smith]

I have this exact problem and have determined that the intake gasket requires replacement per the tests outlined in the bulletin.

 

For those that have done this repair....

What is the torque spec on the bolts and do you put any loctite or sealant on the bolts.  Also any other issue to be concerned about before digging in.

 

Thanks

 

<{POST_SNAPBACK}>

 

 

 

 

I want to say 85 inch lbs on the bolts. I am not 100% sure

 

no sealant or locktite.

[cbxeric]

I am also getting the same trouble codes (p0171 p0174). I have tried checking for a vacume leak and have got nowhere. Before I replace the intake gaskets I am going to try cleaning the MAF sensor. I read somewhere that a dirty MAF sensor can also play games with your fuel trim. I figure it cannot hurt to try.

 

 

Good luck......... Eric.

[hotrodrado]

thanks for the help