2002 Silverado 2500HD 6.0L Power Falls Flat after Warmup

[3500GMC]

Followed this thread and learned me something. Always good to see due diligence when folks post back a result or the fix.

 

[btfarm]

Good to hear the positive outcome Ray.

 

[RayMich]

UPDATE -

Truck is running OK most of the time now. But once in a while loses power and the Check Engine Light come ON. A code check points to problem with Knock Sensor. When he clears all codes, truck runs fine again. Need to replace both knock sensors and while at it fix an intake manifold gasket leak. I suspect that the knock sensor codes are cause by the intake leak, but might as well replace them when the intake is OFF. At 168,000 miles it's time to get new sensors.

The Fuel gauge still doesn't work, so he buys at least $20 of fuel every time he drives the truck. That will have to wait 'till after engine problems are fixed.

We need to replace this truck (It is tired!) but have no time right now to pursue that.

He is currently fixing up the house he just bought (painting, refinishing wood floors, etc.) so he has no time to work on fixing intake gasket leak and replacing knock sensors at the moment.

I will post an update when the knock sensor problem and intake gasket leak are fixed.

Thanks to everyone for your comments and suggestions.

Best regards.

 

[THEFERMANATOR]

Knock sensors were problematic on the gen 3 LS engines because they are mounted in the lifter valley and sealed from the elements by rubber grommets. When you do them, also do the knock sensor harness unless you want to redo the job again.

 

[RayMich]

Knock sensors were problematic on the gen 3 LS engines because they are mounted in the lifter valley and sealed from the elements by rubber grommets. When you do them, also do the knock sensor harness unless you want to redo the job again.

Thanks. I will keep thatvin mind.

 

[WarWagon]

I agree the intake leak could cause a lean condition and excessive or lack of knock.

Keep in mind that ECM's are "artificial stupidity" perfected. That is "code for bad knock sensor" means that the test for the knock sensor failed, sure, but what is under test and how?

For example we had a primitive ECM for a 89 olds that kept coding an ignition module failure. (This was after ECM replacement because at first it would turn the SES light on, limp the engine, and wouldn't store any codes.) During system tests that the ECM carries out: It couldn't advance the timing enough to get a knock signal from the knock sensor. Test apparently is advance till it knocks. ECM failed test with ignition module failure because it couldn't hear a knock with max advance commanded. Problem turned out to be an oil leak that insulated the connector in the knock sensor so it never got a knock signal.

 

[RayMich]

I agree the intake leak could cause a lean condition and excessive or lack of knock.

Keep in mind that ECM's are "artificial stupidity" perfected. That is "code for bad knock sensor" means that the test for the knock sensor failed, sure, but what is under test and how?

For example we had a primitive ECM for a 89 olds that kept coding an ignition module failure. (This was after ECM replacement because at first it would turn the SES light on, limp the engine, and wouldn't store any codes.) During system tests that the ECM carries out: It couldn't advance the timing enough to get a knock signal from the knock sensor. Test apparently is advance till it knocks. ECM failed test with ignition module failure because it couldn't hear a knock with max advance commanded. Problem turned out to be an oil leak that insulated the connector in the knock sensor so it never got a knock signal.

Thank you.

I really appreciate your input.