New GM LB7 Crate Motor w/ 63mm Cheetah. BAD FUEMILEAGE - Chevy and GMC Duramax Diesel Forum
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post #1 of 8 (permalink) Old 11-11-2019, 07:20 PM Thread Starter
 
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New GM LB7 Crate Motor w/ 63mm Cheetah. BAD FUEMILEAGE

I recently installed new GM Crate LB7 in my 2004 2500HD 4x4. ZF6 trans w/ std injectors, stock pump, 63mm Cheetah Turbo, MBRP down pipe and factory exhaust. No tune as of yet

I get 11-12 mph in town and 13-14 mph oh highway. Truck used to get 20 mph.

Please help, need to know how to improve fuel economy.

Thanks
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post #2 of 8 (permalink) Old 11-11-2019, 09:24 PM
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Its a new motor? Might be 100-150k before the motors broken in again

In all honestly, i've heard of guys losing mileage when the replace the first set of injectors. Not sure why either. Seen a few post similar on here in the past.

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post #3 of 8 (permalink) Old 11-12-2019, 06:37 AM
HWI
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Possibly to do with having a stock tune with aftermarket turbo? I wouldn't think it would make that big a difference, but I don't know, that fuel mileage is worse than my truck lifted on 35s.

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post #4 of 8 (permalink) Old 11-12-2019, 06:55 AM
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Not being tuned for the 63mm cheetah would be my first guess. Get some good tuning in it n report back

Race/Pulling truck:2012 Cummins/Built 6.8L/Big air/Big fuel/48RE Swap/PCS 2000/B&M Gated shifter
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post #5 of 8 (permalink) Old 11-12-2019, 08:09 AM
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You need to get it tuned to get the fuel map correct for the cheetah. You have air supply, but probably not enough fueling to spool it correctly on a stock tune. Trust me, it will make a difference

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post #6 of 8 (permalink) Old 11-12-2019, 09:25 PM Thread Starter
 
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Thanks for the feedback. Does anyone have recommendations for tuning? I have heard EFI live is way to go vs canned programming. Any input would be greatly appreciated.
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post #7 of 8 (permalink) Old 11-13-2019, 05:57 AM
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Quote:
Originally Posted by Texag80 View Post
Thanks for the feedback. Does anyone have recommendations for tuning? I have heard EFI live is way to go vs canned programming. Any input would be greatly appreciated.
With an aftermarket turbo you really have to go EFI Live, every canned tuner I know of is designed around stock turbos.

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post #8 of 8 (permalink) Old 11-13-2019, 06:01 PM Thread Starter
 
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I am new to tuning. What programming equipment / hardware should I purchase? Who are best EFI live tuners?
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