Loss of power.

[twl2u87]

Hey guys, new to the forum and duramax trucks. I recently got a 2005 Chevy Silverado 2500hd 4x4 CC with 248xxx miles. Truck is pretty stock except a 4” straight exhaust without a muffler. Resonator delete. Pcv reroute. And some Max Power mp8 module that was already on the truck when I bought it.

My problem started maybe a week back. I’ll start by saying when I first test drove the truck and the couple weeks following, it pulled hard and really got up and goed. But now not so much... feels like a loss of boost pressure. And I don’t have a boost gauge or egt gauge currently so that doesn’t help me.
But I’ve replaced fuel filter with an ac Delco filter. I performed a boost leak test and surprisingly found no leaks anywhere. Truck feels like I’m running on just engine and no boost. I can hear the turbo once I first barely get on it but if I give it more on the throttle, I don’t hear it anymore or like I did previously.

I’ve read through many forums about similiar problems. Limp mode, boost leak, bad diesel fuel, turbo vain position sensor, bad injectors, etc etc.
just looking for some feedback before I start throwing parts at it.
Anything I can check or try?

Thanks

 

[ChrisPerry]

Is the check engine light on? If so what codes.

 

[twl2u87]

Is the check engine light on? If so what codes.

Haven’t had any check engine lights on for this problem. That’s what is odd..

 

[JoshH]

Get a scan tool of some sort and verify the engine is commanding and achieving proper boost, fuel pressure, fuel quantity, etc. We can't guess what the problem is without knowing what the truck is or isn't doing.

 

[ChrisPerry]

Is it blowing black smoke when floored.

Start with cleaning the maf, check that the resonator plug hasn't popped out, did you accidentally turn the programmer to a smaller tune.

 

[twl2u87]

Get a scan tool of some sort and verify the engine is commanding and achieving proper boost, fuel pressure, fuel quantity, etc. We can't guess what the problem is without knowing what the truck is or isn't doing.

True. Thanks, I’ll find a local diesel shop or some local with the ability to do that.

 

[twl2u87]

Is it blowing black smoke when floored.

Start with cleaning the maf, check that the resonator plug hasn't popped out, did you accidentally turn the programmer to a smaller tune.

No black smoke. I’ve cleaned the maf sensor, but will check into it again. Resonator plug is still firmly seated.

Possibly? The dial switch for max power module in the cab of the truck does not illuminate a light where it should. 3 wires to that switch. Red, black and a green. I tested to see if power was getting to the switch yesterday.. and once I put the test light to the red wire, it lit up, than the idle of the motor came down a 100rpms or so. It was odd

 

[ChrisPerry]

Seeing that the switch isn't acting right, I'd remove the mudule and see if the truck runs correctly.

 

[twl2u87]

Seeing that the switch isn't acting right, I'd remove the mudule and see if the truck runs correctly.

I will try that soon. Thanks. I appreciate the input.

 

[NC-smokinlmm]

Remove the module...