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i have a 2004 flatbed single cab, 4wd allison/dmax. its got 37,000 miles on it, just over the warranty. And i think i might need new injectors. I just changed all the filters, that didnt help my power, and it shifts into 5 gear religiously at 65 mph, all the shift points seem mildly late. Don't the allisons have adaptive shifting or something, it might shift like that due to a lack of engine power. i also own a 2005 duramax and the differences in power are night and day is the low power just a characteristic of the LB7s? i have my foot pretty much all the way to the floor most of the time just to make it go down the highway. and this is unloaded. In my LLY i can keep up with my buddys Camaro. Whats Wrong??
 

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have you changed your tranny fluid? Also, I know that my LB7 accellerates better if I don't put it all the way to the floor. I can keep up with most vehicles at about half throttle. You can get the allison TAPS reset and see if that helps, but unless it has A LOT of white smoke and the crankcase isn't full, then I can't see it being injectors. You been filling up with fuel at the same station, or are you all around. It only takes 1 bad tank to cause problems. You might want to try and clean you MAF sensor. Use some electrical contact cleaner or rubbing alcohol on it. That might help.....When you said you changed all your filters, you changed the allison spin-on, fuel, and air filter??
 

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I vote for the fuel issue. Poor quality fuel is the major cause of low power, hard starting, and a bad smell from the exhaust. AND- it will ruin the injectors in the long run. I only buy fuel at high-volume, chain fuel stops to reduce the chance of getting a tank of poor quality fuel, the slightly higher price is well worth the protection. The stock LB7 has enough power to tow or haul anything legal with ease, providing the owner does his part by performing proper maintenance.
 

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i would have to say there is nothing wrong. that is how all chevys r. :rof
 

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i dont know if it helps the power and responce on the duramax's....but i know you can take a 6.0 ford that seems to be running just fine....and run a bottle of cetane booster in it....and it really makes a difference. you can not know for sure the quality of the fuel your getting and while this may not be your problem....it may be worth trying...not just for you...but for anyone with these newer diesels that seem pickier about fuel quality.......Marc
 

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I tried some diesel power cetane booster and it seemed to blow just a little bit more black some on hard acceleration...
 

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Did A Dura Do Dat said:
I tried some diesel power cetane booster and it seemed to blow just a little bit more black some on hard acceleration...
it doesnt seem to affect 7.3's all that well....they arent picky about fuel quality like the newer motors.........Marc
 

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heck I didn't care, I saw more black smoke and that was enough to make me happy!
 
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