Duramax Diesels Forum Truck of the Week
  #1  
Old 10-18-2018, 12:32 PM
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Default Loss of power.

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 4Ē 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. Iíll 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 donít have a boost gauge or egt gauge currently so that doesnít help me.
But Iíve replaced fuel filter with an ac Delco filter. I performed a boost leak test and surprisingly found no leaks anywhere. Truck feels like Iím 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 donít hear it anymore or like I did previously.

Iíve 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
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Old 10-18-2018, 12:45 PM
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Is the check engine light on? If so what codes.
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02 GMC 2500HD, EC/LB, LB7, 2wd, 6" lift, 35" tires. ds LML manifold, PPE 260 hp tune, boost valve, race plug, Airdog 165 lift pump, CAT filter mod, mechanical egt and boost gauges, SB intake, high flow turbo horn, ported turbo exhaust housing, kbd drop in wheel, Banks Bighead wastegate, egr blocked, intake heater delete, PPE downpipe, 5 " exhaust w/ cat delete, Mike L built trans w/ Goerend R converter. Levi's heat blankets

7-6-17...New headgaskets, studs, Fed heads, and LDS replacement injectors @ 202,239 Miles
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Old 10-18-2018, 01:01 PM
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Quote:
Originally Posted by ChrisPerry View Post
Is the check engine light on? If so what codes.


Havenít had any check engine lights on for this problem. Thatís what is odd..
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Old 10-18-2018, 01:21 PM
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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.
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Old 10-18-2018, 01:31 PM
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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.
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02 GMC 2500HD, EC/LB, LB7, 2wd, 6" lift, 35" tires. ds LML manifold, PPE 260 hp tune, boost valve, race plug, Airdog 165 lift pump, CAT filter mod, mechanical egt and boost gauges, SB intake, high flow turbo horn, ported turbo exhaust housing, kbd drop in wheel, Banks Bighead wastegate, egr blocked, intake heater delete, PPE downpipe, 5 " exhaust w/ cat delete, Mike L built trans w/ Goerend R converter. Levi's heat blankets

7-6-17...New headgaskets, studs, Fed heads, and LDS replacement injectors @ 202,239 Miles
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Old 10-18-2018, 01:34 PM
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Quote:
Originally Posted by JoshH View Post
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, Iíll find a local diesel shop or some local with the ability to do that.
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Old 10-18-2018, 01:40 PM
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Quote:
Originally Posted by ChrisPerry View Post
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. Iíve 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
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Old 10-18-2018, 02:13 PM
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Seeing that the switch isn't acting right, I'd remove the mudule and see if the truck runs correctly.
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02 GMC 2500HD, EC/LB, LB7, 2wd, 6" lift, 35" tires. ds LML manifold, PPE 260 hp tune, boost valve, race plug, Airdog 165 lift pump, CAT filter mod, mechanical egt and boost gauges, SB intake, high flow turbo horn, ported turbo exhaust housing, kbd drop in wheel, Banks Bighead wastegate, egr blocked, intake heater delete, PPE downpipe, 5 " exhaust w/ cat delete, Mike L built trans w/ Goerend R converter. Levi's heat blankets

7-6-17...New headgaskets, studs, Fed heads, and LDS replacement injectors @ 202,239 Miles
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  #9  
Old 10-18-2018, 02:25 PM
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Quote:
Originally Posted by ChrisPerry View Post
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.
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  #10  
Old 10-18-2018, 04:14 PM
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Remove the module...
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