100hp injectors poor fuel mileage - Chevy and GMC Duramax Diesel Forum
01-04.5 LB7 Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission Ect

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Old 11-29-2010, 07:22 PM   eBay Motors  #1 (permalink)
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100hp injectors poor fuel mileage

LB7, I just replaced all stock injectors at 130,000 miles because of fuel in crankcase. I replaced with Scheid Diesel Lightning 100 hp injectors, and installed a FASS lift pump with filters. Runs great, has more power, doesn't smoke much.

I just pulled a trailer 500 miles empty at 74-79 mph and got 11-12 miles to gallon. Returned loaded with a Kubota RTV running 74-79 mph and got 10-11 miles to gallon.

When I push the speed to 79 mph (2400 RPM) empty or loaded the "service engine soon" light would come on. I am not sure what the code is, or how to get it.

Why is fuel mileage so bad? How can I get back to stock fuel economy of 15 mpg.
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02 Silverado 2500HD Crew Cab 4X4, 132000 miles,
Scheid Diesel Lightning 100 HP injectors, FASS lift pump & filter

Last edited by Randy Gough; 11-29-2010 at 07:25 PM. Reason: Did not list engine lb7
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Old 11-29-2010, 07:26 PM   eBay Motors  #2 (permalink)
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Is the truck tuned? with EFI live or HP Tuners? (a programmer is not tuning, and won't compensate for larger injectors properly).

Larger injectors require custom tuning if you really want them right....
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Self built/tuned sideways s366 setup | DPC converter / Co-Pilot | 1792 / BD Filter| Black 5" Hood Stack | Homebuilt Trac Bars | Coil-overs | 250psi water/meth | Black MM951's | roll pan | Autometer/ISSpro/UltraGauge | sleeves | self Lowered | deep pan etc.
12.61 @ 105 - 5800ft elev (stock trans) 12.6 vid

Parted out my car for a Pilot's License!!!
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Old 11-29-2010, 07:28 PM   eBay Motors  #3 (permalink)
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What was the mileage before??it does sound unusually low but I've heard injectors will do it.
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EFI LIVE TUNED by wory killis
TRANS BY SMOKIN DIESEL
30% LDS INJECTORS,LBZ FPR
BATMOWHEEL PORTED STOCKER
KENNEDY LIFT PUMP,LML DS MANIFOLD
DRP TANK SUMP;NICTANE CAT FILTER
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Old 11-29-2010, 07:32 PM   eBay Motors  #4 (permalink)
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No tuners or programmers, bone stock.

So I need to have it tuned? How? Where?
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02 Silverado 2500HD Crew Cab 4X4, 132000 miles,
Scheid Diesel Lightning 100 HP injectors, FASS lift pump & filter
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Old 11-29-2010, 07:33 PM   eBay Motors  #5 (permalink)
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well going 80mph certainly ISN'T helping your MPG's.

Slow down to 65-70.
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Old 11-29-2010, 07:36 PM   eBay Motors  #6 (permalink)
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can you check your codes somehow im thinking it is a 1093
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Old 11-29-2010, 07:38 PM   eBay Motors  #7 (permalink)
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What is a 1093 code? Is it a fuel pressure/supply issue?
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02 Silverado 2500HD Crew Cab 4X4, 132000 miles,
Scheid Diesel Lightning 100 HP injectors, FASS lift pump & filter
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Old 11-29-2010, 07:40 PM   eBay Motors  #8 (permalink)
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How can I check the code?
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02 Silverado 2500HD Crew Cab 4X4, 132000 miles,
Scheid Diesel Lightning 100 HP injectors, FASS lift pump & filter
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Old 11-29-2010, 07:41 PM   eBay Motors  #9 (permalink)
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Ok... heres basically whats happening.

Your injectors open and close for a period of time when they spray- (Pulsewidth). Obviously when they are opened longer you get more fuel (heavier throttle and rpm)... of course fuel pressure plays a part in how much fuel is injected as well.

With larger injectors, you are getting more fuel injected per injection event. It will probably effect you the worst under cruise, light throttle etc. I would imagine the throttle is a little more touchy depending on how much the MAF is limiting fueling.

With custom tuning you can adjust injector pulsewidth to compensate for the larger injectors, you can also adjust injection timing, fuel pressure etc. to dial in everything.

You should get the CEL pulled.... most auto parts stores will scan for codes for free.

EDIT: Anyone know how these "100hp" injectors would stack up against a % over injector?
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06 LBZ / 6spd Allison 4x4 ec/sb
Self built/tuned sideways s366 setup | DPC converter / Co-Pilot | 1792 / BD Filter| Black 5" Hood Stack | Homebuilt Trac Bars | Coil-overs | 250psi water/meth | Black MM951's | roll pan | Autometer/ISSpro/UltraGauge | sleeves | self Lowered | deep pan etc.
12.61 @ 105 - 5800ft elev (stock trans) 12.6 vid

Parted out my car for a Pilot's License!!!
GravityKnightFlying

Last edited by GeneralTJI; 11-29-2010 at 07:43 PM.
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Old 11-29-2010, 07:41 PM   eBay Motors  #10 (permalink)
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low rail pressure during power enrichment
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