poor mpg 7.3L - PowerStrokeNation : Ford Powerstroke Diesel Forum
 
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post #1 of 7 (permalink) Old 01-15-2011, 05:19 PM Thread Starter
sgh
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poor mpg 7.3L

I have a 97 F350 4x4 crew cab; stock except for 3 inch down pipe. It has 3:55 gears, just changed from 4:10, 5 speed stick, K&N air filter. Tires are 285/75/16, it gets about 14 mpg at 70 mph - does this sound right? Seems low from what I have read on PSN. It does have some soot on fire wall so I think the up pipes are leaking. Could that be the cause of poor mpg? How hard is it to get these pipes out? Thanks for any advice you can give.

I also unplugged the waste-gate and it seems to run better.
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post #2 of 7 (permalink) Old 01-15-2011, 05:21 PM
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Re: poor mpg 7.3L

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Originally Posted by sgh View Post
I have a 97 F350 4x4 crew cab; stock except for 3 inch down pipe. It has 3:55 gears, just changed from 4:10, 5 speed stick, K&N air filter. Tires are 285/75/16, it gets about 14 mpg at 70 mph - does this sound right? Seems low from what I have read on PSN. It does have some soot on fire wall so I think the up pipes are leaking. Could that be the cause of poor mpg? How hard is it to get these pipes out? Thanks for any advice you can give.

I also unplugged the waste-gate and it seems to run better.
There is no wastegate on these old trucks.


Sounds normal for the speed, soot on the firewall is leaking uppipes.

02 f250
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post #3 of 7 (permalink) Old 01-15-2011, 05:24 PM
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Re: poor mpg 7.3L

Thats not too far off, Is your speedo calibrated for the tires? Take a GPS and see how fast you are really going if not, it could be a few mph off. But 14-16 would be close for a CC depending on how cold it is where you are.

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post #4 of 7 (permalink) Old 01-23-2011, 12:19 AM
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Re: poor mpg 7.3L

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Originally Posted by stroked99_1/2 View Post
Thats not too far off, Is your speedo calibrated for the tires? Take a GPS and see how fast you are really going if not, it could be a few mph off. But 14-16 would be close for a CC depending on how cold it is where you are.
good point.
the cold will kill your mileage.
leaking uppipes will mess w/ the turbo spool and that could be causing you to give more go-pedal in response to the lack of turbo spool.

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post #5 of 7 (permalink) Old 02-24-2011, 09:51 PM
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Re: poor mpg 7.3L

also winter fuel right? i have heard that it plays a 2-3 mpg diff.

96- FF 350 200s. 76mm Billett GT4202R. Big Oil. Twin E-Fuel.
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post #6 of 7 (permalink) Old 02-24-2011, 11:59 PM
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Re: poor mpg 7.3L


winter fuel regularly drops my mileage by 2-2.5...
also, I know it sounds like an awfully small change to make a big difference, but slow down to 65 if you can bear it.
Do you have EGT gauges?

Dan
96 Powerstroke: 6637, downpipe to dump exhaust, 140v IDM and a shift kit.

84 Honda Sabre V65 1100: pipes, jet kit and new tires. Faster than I think I'll ever need.
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post #7 of 7 (permalink) Old 02-25-2011, 02:35 AM
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Re: poor mpg 7.3L

Check your brakes. Fords are fanous for dragging brakes.

Check your EBPV. Those things stick shut. Just like an exhaust brake.

Carefully driven (depending on terrain) that truck should give 17 easy.

2000 F-350 SC 4x2 6 speed
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