I just bought my first Diesel ever last week, an 08 GMC 2500Hd Dmax, so I'm pretty much a newbie. My question relates to the DPF cleaning or regenerating, whatever you call it. When the DPF cleans itself, is the engine supoosed to sound different while driving? I just took the truck out somewhere, and it sounded a bit different. Also, I couldn't really here the turbo at all. Is that normal?

there can be a slight sound in engine sound but hard for me to tell. The first few times it does regen you may smell something burning. That is some tags on the DPF burning off and residue from manufactoring of the exhaust system. At idle it runs maybe 100rpm or a bit higher over stock idle rpm. There is knowing that will tell you are regenerating. There are a few devices that display this info when it is happen. Search for Edge Insight and DashHawk II. When it regens many things go on like adding addtional fuel to generate higher exhaust gas tempertures EGT. The run roughly 1100 to 1200 degrees F during regen. There is also an Intake Throttle valve that closes to about 20percent while just driving normally but if accelerating it opens back up to allow more needed boost. Once regen is done it opens back to normal running position. This is the sound that is heard when you shut the truck off. Sounds like a motor cycling 3 or 4 times. All normal for stock.

With the DOC and DPF it is hard to hear the turbo to spool plus current default stock OS the truck is running. Using one of the mention devices above can show turbo boost pressure plus the EGT sensors on both sides of the DPF. Granted those EGT sensors are not the best as location goes. Many perfer to add an external EGT off the exhaust manifold for that.

Brian

It's just wierd because the truck doesn't sound the same as it did before this. I've only had it since July 24 and it is new. I just took it out again, and no change. How long does a normal regen usually take?

It's just wierd because the truck doesn't sound the same as it did before this. I've only had it since July 24 and it is new. I just took it out again, and no change. How long does a normal regen usually take?

Usually 20min or 20 miles or so, you can tell by the mpg on the dic taking a dump, sometimes longer, sometimes shorter.

If you shut the truck off before the regen is through, it will pick back up when you head off driving again. If you notice a chlorine smell and a hot popping and cracking exhaust system, it was probably regenerating when you shut it off. Don't be tempted to touch the megaphone unless you want some pain.

^Well that makes sense then. The MPG has been dropping since yesterday like crazy and I did smell something when I turned it off earlier. I guess that answers my question. Thanks guys.