Reduced Engine Power duramax

MaxPayne

New member
Jul 27, 2020
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Hi!

My truck is a 2008 Silverado (Duramax 6.6)

For the past few days my truck has had a loss of power and indicates (reduced engine power)

The problem is intermittent. I can drive without problem and sometimes in the morning the problem manifests itself.

I noticed that the problem happens when I leave in the morning, after 2 or 3 km the problem happens.

Otherwise I can drive a long time without a problem, but as soon as I turn off the engine, and wait 2 or 3 minutes (for example, time to stop at the convenience store), when I start the truck, the problem is present.

It doesn't happen every day. I can ride 2 or 3 days without problem, and I can have the problem 2 or 3 days in a row.

Anytime the problem is there, I turn off the engine, wait 10 seconds, and restart the truck and it's okay. I can do 100km without problem.

Each time I turn off and restart the engine and everything is fine.

If a few things were dirty, the problem would be there all the time.

If I drive a few minutes with the problem, the engine light comes on.

At first I had a code for the EGR, but I cleared the code to see if it would come back. Then I had a code for the MAP SENSOR. I changed the MAP SENSOR. Then I still had the same code, I changed the air filter.

Today I drove with the problem to the garage. But while I was driving the following code came out (Turbo underboost performance P0299)

The problem went away, but no turbo, it was driving slowly.

When I got to the garage, he turned the truck off and cleared the code, and now the turbo is working fine.

It’s a little silliness, but I don’t find the problem.

Sorry for "my english", translate witch google.
 

2004LB7

Super Moderator
Staff member
Dec 15, 2010
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It almost sounds like you have a short or break on your 5 volt reference circuit. that's the only thing I can think of that is related to all those parts
 

2004LB7

Super Moderator
Staff member
Dec 15, 2010
7,099
2,205
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Norcal
there is a 5 volt circuit that runs to each of the sensors, I believe, that powers the sensor or the sensor uses to regulate the signal back to the ecm. if there is a break or short in that line then some or all of the sensors can give codes.

should be easy enough to test with an VOM. most sensors will have three wires. one for that 5 volts, another for ground and one for the signal.

I'm not sure which ones are grouped together off the top of my head, but I believe these use 5 volts. MAF, turbo vane position, oil pressure, throttle, egr position, map or baro sensor,

I would think a short would effect all the sensors on the circuit at the same time so it would more likely be a break in the wire or bad ground. check the large bale connectors for loose or bent pins too

and as mentioned, could be a sticking or leaking egr valve too since each of the codes are related to air movement which the egr effects when open