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strokin now cummin later!
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Discussion Starter #1
before i put in the imjectors, dv, turbos, timing, etc. i was only getting 15mpg. only mods were afc gutted and no plate. intake, exhaust, and gsk.
now im getting 14-15 mpg modded. why is the mileage so bad? is it cuz the afc isnt tuned. wouldnt think it would make that big of a difference just crusing down the highway.
 

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strokin now cummin later!
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1,116 Posts
Discussion Starter #3
i understand the right foot. but i usually have the crusie set at 75 on hwy get maybe 400 miles to a tank.
 

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gone fishin!
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2,833 Posts
might be the injectors???? not sure tho....... might bump your time a few more * and you might pick up some more mpg.....
 

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off to another home
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15,472 Posts
put the afc back together and tune it.

i was able to do 16-20 with 4.10s and dealing with L.A. traffic daily. i would do 500mi easily on a tank, did over 600 a few times as well.

Garrett
 

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Hot Rod Farm Boy
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1,226 Posts
Dirty air filter?
 

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Senior Member
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1,836 Posts
I think that I would start with the basics, tire pressure, tire rating E, are the brakes dragging, wheel bearings (temperature for balance to start), toe-in, wind drag... you started at 15, it should have been 20-21.

Six years ago I was driving a ton truck - the co had 2 the same - I made 16 mpg and the other made 9, we traded trucks and had the same results I made 16 with the truck that had been logging 9 and my truck made 9 with the other driver. It even made 16 when I put the Isuzu on a towbar to relocate, I took care to control windage with tarps and run easy. The other fellow drove comfortable - both feet on the floor when I rode with him.
 

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Hot Rod Farm Boy
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1,226 Posts
Does that pickup have 4.10s or 3.55s?
 

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Senior Member
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4,827 Posts
The flatbed is hurting your mileage. I lost 3-4 mpg putting one on my '97 dually.

Even with 4.10 gears, I got 16mpg stock with it. And nearly 18 after I modded it. Flatbed knocked me back to 12-15 range. Mostly 13-14, highway or not. No matter how I drove.
 

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strokin now cummin later!
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1,116 Posts
Discussion Starter #10
Yeah it don't matter. If I'm towing haulin or empty. Same mileage. Tires, bearing, alinement, etc everythings good.
 

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Senior Member
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Put the plate back in and reassemble the AFC and tune it.

I dynoed 416hp/892tq with my '97.

TST 10 plate and AFC housing full forward, adjusted star wheel, 191DVs, DDP stage 4 injectors, HTT Killer B2 64/14, ATS exhaust manifold, BHAF, 5" exhaust to 5" turn-out stacks. And, got the aforementioned almost 18mpg.
 

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Senior Member
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2,063 Posts
Put the plate back in and reassemble the AFC and tune it.

I dynoed 416hp/892tq with my '97.

TST 10 plate and AFC housing full forward, adjusted star wheel, 191DVs, DDP stage 4 injectors, HTT Killer B2 64/14, ATS exhaust manifold, BHAF, 5" exhaust to 5" turn-out stacks. And, got the aforementioned almost 18mpg.
:whs More than likely you are over fueling before the turbo can spool and just wasting fuel. The fuel plate will limit that.
 

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Junior Member
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46 Posts
Just for hahas check fuel pressure. I had a customer with a 95 12v burn through a tank in 100 miles. I found absolutely nothing wrong except low inlet fuel pressure. I put a new overflow valve in and it was fixed. I seriously thought someone was stealing his fuel, but he claimed he didnt do anything different, and the next tank was 500+. Probably not your issue, but worth a shot.
 

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strokin now cummin later!
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1,116 Posts
Discussion Starter #15
is there a good place to stat when adjusting the star wheel and preboost screw?
 

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Senior Member
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I had mine full forward, til i went to Colorado. Air is too thin up there to spool the 64 worth a crap. Put it back towards the middle helped and I kept it there. Worked pretty good.
 
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