Power Loss-Injector Problem- Fuel Economy

[20050824|7|006327|000000|216.230.93.198]

Gang,

I am a bit cornfused here and I am looking for your advice. I have a 2003HD with of course the diesel and I am either gonne shoot the dealer or the truck. I think my bloody injectors are taking a nose dive and according to the dealer nothings wrong with it. The truck has only been in the shop 3 times now for this. Here's what I am seeing. Periodically at around 2300-2600 RPM I get a chattering noise out of the motor for about 2-3 seconds and then it disappears. Its always during acceleration. At first I thought I was hearing things until I got it to do it when I was running the truck at 80MPH down the freeway. The exact same noise just louder and longer if I maintained that speed. AGain it comes and goes. To top it off I went from 19MPG down to 11-13MPG or 600miles per tank to 300 or so. I wouldnt worry if I had tweaked the performance of the truck or was towing but I havent done either. The truck is bone stock and I have no clue what is wrong. I think its the injectors. Any thoughts? PS. The dealer cant find a thing wrong, and told me the speed limit was 65 to which I replied then don't make a truck go 80+mph.

Thanks,

Tim

[D-MAX]

Read This ;)
http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=3;t=007319
Diesel engine fuel injection systems that use a common rail system, as the Duramax diesel does, may or may not have what is referred to as pilot fuel injection at the lower engine speeds. Pilot fuel injection is defined as a pre-injection of a small quantity of fuel 5 to 20 crankshaft degrees before the main fuel injection. This pre-injection softens the main injection pressure rise and reduces combustion noise. At engine speeds above 2600 RPM, and a fuel quantity supply greater than 35 cu mm, it is necessary to eliminate pilot injection to meet emission requirements. When driving at or above these speeds, main injection combustion noise may be noticeable. It is normal and not harmful to the engine.
When traveling in 5th gear, the pilot injection to main injection transition is typically in the 136km/h (85 mph) range, however it may also be heard under heavy acceleration and when pulling loads up a hill during shifts at or above 2600 RPM. Customers that install the fifth gear inhibit switch, (ODLO), may encounter the fuel knocking of main fuel injection at speeds around 107 km/h (67 mph) in fourth gear between 2600 and 2700 RPM. This sound is considered normal and is to be expected.
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[20050824|7|006327|000000|216.230.93.198]

Dmax,

Thanks for the reply and I am glad to know that is normal. I just thought it was strange since I have a 2003 and my brother in law has a 2004 that only my beast made noise. Can you explain or have any thoughts as to why my fuel economy dropped way off? My driving style and distance is unchanged its all freeway.