Help, Engine Power Is Reduced on Chevy Duramax

[Ford Idaho]

DPF is under the truck.

https://www.google.com/search?q=dura...w=1366&bih=712

[hrlyguy2]

2007.5 is when the started the new body style.Lmm is name for your motor.
Lb7.lly.lbz lmm.lml are all gm.diesel engines

[hrlyguy2]

No separate section.

[OKI Marine]

Without checking any codes DPF sounds like a high probability. I will have to take it in to the shop tomorrow and get it looked at. thanks for everyones help.

[Herk7769]

I believe it is back by the tail cone.
There should be a diesel fuel line going to it.


2010 Duramax LMM Turbo Diesel DPF Diesel Particulate Filter Exhaust GM | eBay

I know that was for the 2010, but it looks kinda like that.

http://www.ehow.com/how_8561954_clea...l-duramax.html

[JFM-jr]

If it is an 08 it absolutley has a DPF and if there was an issue with the DPF the dashboard display would state "Clean exhaust filter" if it were a clogged DPF due to non completion of regen cycles. I would change the fuel filter as suggested and then if that does not work get the code checked. As stated earlier your shooting blind otherwise.

[jevanb]

could be a multitude of issues, take the truck to a auto parts store and pull the code, or codes. could be the DPF,low rail pressure , MAF, trans,.ect...the list can go on and on that all cause reduced power. But with out the code everyone is just speculating..

[mhartzel]

I'm comparing apples to oranges here, but my gas 2011 Silverado had a similar issue. Was the throttle position sensor.

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[Herk7769]

Just sayin'

Mine is an 08 Duramax.

Had the exact same error.

Codes showed clogged EGR valve and intake air restriction confirmed by diagnostic run by OnStar.

Solution by GMC dealer was to drop the camper in his yard; drive it back onto the highway to the next exit and back.

By the time I got back it was running great; hooked back up and continued to Florida for 2 months of trouble free driving. Total cost out of pocket - zero.

[JFM-jr]

Herk that sure sounds to me like a remedy for a DPF issue and not the EGR. When the DPF does not complete a regen cycle to clean itself of accumulated soot the prescription is to drive it on the highway. Regen is put on hold under 35 mph in these trucks hence the highway driving needed. After a few failed attempts the "Clean exhaust filter" message can appear.

[SKnight]

OK, many things can cause a reduced engine power message, anything from a sensor error to a faulty hard part, so unfortunately it's guessing. A DPF error will be expressed as a regen message and no, idling long enough to fix a wheel WILL NOT plug it up.

Reduced power merely expresses that a fault code that can potentially harm the engine or it's other components has been detected and the engine will seem weak, but will get you off the highway. Some codes are multiple drive cycle items, but will flag that message to get your attention. Turn it off, key out of the ignition for a couple of minutes to let the system power down fully. Then restart it. Good chance the reduced power message will be gone and it will drive normally, but don't ignore the check engine light.

One guess I'll toss, have you ever filled the DPF fluid? I don't recall how the 2008 trucks indicated they needed filling, reduced power would be a hell of a way to indicate it but I wouldn't put it past GM. Since you didn't know you had a DPF, the tank could be empty. That's a total guess, but not a bad place to start.

[JFM-jr]

No DEF fluid on GM until 2011 model year

[SKnight]

Originally Posted by JFM-jr

No DEF fluid on GM until 2011 model year

That's right, they trained us on it as coming but didn't say when.

I've slept since then.

[Herk7769]

Originally Posted by SKnight

One guess I'll toss, have you ever filled the DPF fluid? I don't recall how the 2008 trucks indicated they needed filling, reduced power would be a hell of a way to indicate it but I wouldn't put it past GM. Since you didn't know you had a DPF, the tank could be empty. That's a total guess, but not a bad place to start.

2008 trucks do not use DPF fluid. They add diesel to the particulate filter and burn it while racing the engine.

The reduced power message comes on to tell you it is happening. Those were the codes my engine delivered due to an incomplete regen. I never had it before and I shut off the engine before it could complete.

[JFM-jr]

Originally Posted by Herk7769

2008 trucks do not use DPF fluid. They add diesel to the particulate filter and burn it while racing the engine.

The reduced power message comes on to tell you it is happening. Those were the codes my engine delivered due to an incomplete regen. I never had it before and I shut off the engine before it could complete.

As I suspected incomplete regen and it takes more than one incomplete to trip the reduced power message. I have a monitor on my truck that I can watch the accumulated soot grams in the DPF drop as I drive when in Regen. A small icon appears letting me know it is in regen mode. As I stated earlier the process stops under 35 mph so local trips will not allow soot to be burned out. It takes about 30 miles of highway driving to clean it. The 08 like mine goes into regen when the ECU sees 42 gram of soot or about 375 miles wich ever comes 1st. My truck ends up using milage last 2 regens were both under 25 soot grams when it started regen. Heavy towing can produce hot enough exhaust gasses to clean the filter passively.

[OKI Marine]

Update on the Engine Power is Reduced. I never had any reduction in power. I did have the engine light stay on. I took the camper to the storage lot to unhook. I got a message to clean exhaust filter and to see owner's manual. After unhooking I took the truck out on the highway and maintained a speed of 70 mph. After a short drive, the message went away. however, i still have the engine light on. I guess I will ned to have it checked.

[kz08h5]

OKI Marine,

Wait a few days before wasting your money taking your truck to the dealer. When the truck goes into Reduced Power Mode it turns on the Check Engine light. It takes a number of ignition cycles to turn it off. I am not sure what that number is but something between 5 & 10. I just had this happen while in Florida earlier this month. It was hot out, above 90, and I let the truck idle with the AC on for about 20 minutes. They way GM has designed the diesel system, idling and hot out are not something the engine control system likes. It does the same thing if you are towing and driving slow.

Put a few 50 mph miles on it and a regen will happen, then a few ignition cycles later the Check Engine light will go off.

[JFM-jr]

Originally Posted by OKI Marine

Update on the Engine Power is Reduced. I never had any reduction in power. I did have the engine light stay on. I took the camper to the storage lot to unhook. I got a message to clean exhaust filter and to see owner's manual. After unhooking I took the truck out on the highway and maintained a speed of 70 mph. After a short drive, the message went away. however, i still have the engine light on. I guess I will ned to have it checked.

This sounds oddly familiar

Originally Posted by JFM-jr

. When the DPF does not complete a regen cycle to clean itself of accumulated soot the prescription is to drive it on the highway. Regen is put on hold under 35 mph in these trucks hence the highway driving needed. After a few failed attempts the "Clean exhaust filter" message can appear.

Drive the truck as for a few days as suggested the light will probably clear for you. What you had happen is very common with guys that take frequent short trips.

[OKI Marine]

Originally Posted by kz08h5

OKI Marine,

Wait a few days before wasting your money taking your truck to the dealer. When the truck goes into Reduced Power Mode it turns on the Check Engine light. It takes a number of ignition cycles to turn it off. I am not sure what that number is but something between 5 & 10. I just had this happen while in Florida earlier this month. It was hot out, above 90, and I let the truck idle with the AC on for about 20 minutes. They way GM has designed the diesel system, idling and hot out are not something the engine control system likes. It does the same thing if you are towing and driving slow.

Put a few 50 mph miles on it and a regen will happen, then a few ignition cycles later the Check Engine light will go off.

Yes, I have done several ignition cycles already and after two this morning, the engine light went out. Truck seems to be running fine. I have never had this happen before and have had the truck for over five years. Guess it will be something that i will need to be aware of. thanks for everyones help

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