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Low power/poor fuel economy

Created On Thursday January 07, 2016 11:24 Diesel Talk
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Note Thursday January 07, 2016 11:24 View thread in raw text format
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I bought a 2007 western star in July of 2013. it has a 14.0 L Detroit in it. For the first 2 months I owned it,it ran great. it had 765k on it when i bought it. The truck got 6.2 mpg fully loaded pulling a reefer at the time. after that the jake boost seemed to be intermitten on the high setting getting 35-38lbs "sometimes" but mostly around 25-28lbs. The power and fuel economy dropped off roughly the same time. from there on gettting around 5.4 average loaded and upwards to 7.4 empty . the inj codes are set at 75, it gets on the power side 42-44 lbs of boost. Nothing that anyone has tried on this truck has ever changed the mileage or the lack of power. also during the first 2 months it "burped" through the intake at times, but has not done that since the power and mileage went to hell. pulling any kind of hill with a load on caused the coolant temp to borderline over heat and high exhaust temps. in some cases it went into derate.

I recently had an in-frame done on it,rebuilt head,fresh injectors,jake tune up and the inj haness replaced. at 6500 miles after the in frame,it dropped from 5.2mpg to 4.9mpg and now is lucky to get 4.5mpg. that mileage decrease happened in about a weeks time.

the cac has been tested. fuel pressure at 2100 rpm is 45lbs. the vpod is working correctly. the turbo is good and the actuator is not leaking. it was tested for air in the fuel system,that is ok too. The shop installed a test ecm and reflashed it for my VIN. installing that ecm and putting the correct inj codes in it,the boost dropped from a peak of 44 to 32 max. fuel mileage dropped to 4.1-4.3mpg and it was very sluggish. the jake boost seemed unchanged. My ecm was reinstalled with the correct inj codes in it,the boost is 40 lbs max, but it takes 17-1800 rpm to reach that amount. jake boost is back to max 28 lbs.

too my knowledge this truck did not have any performance ecm programming in it when purchased. anyone here have any idea's where to look? 20k on and inframe and its now worse than its ever been.

Edited: Thursday January 07, 2016 at 11:29 by flatbedder
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Note Sunday January 17, 2016 13:41 View users profile View thread in raw text format
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just off the wall guess , the values have gotten tight or losse , may need to redo the top end
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