I have posted on here before about this, but here we go again.....What should i do about getting better fuel mileage. I am getting no better than 10mpg. You can see in my sig. what i have. Where should i start? (buying a new truck perhaps) /ubbthreads/images/graemlins/smile.gif It just gets me that a dully can pull 17mpg and im only getting 9.5mpg. something aint right.
Fuel Mileage
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Have you had all of your injectors tested (for pop-off pressure and leakdown)? Turbo injectors should pop off at a higher pressure than n/a injectors, so you may need to adjust your timing some. Remember the higher pop off pressure has the net effect of retarding the timing. Your off-road setup will hurt mileage some, but it should be better than 9.5.
Go over to the Ford Truck Enthusiasts forum and search for the thread called "Using glow plugs to super tune the engine", you might learn some things there you might use to diagnose your timing and fuel variables.
Go over to the Ford Truck Enthusiasts forum and search for the thread called "Using glow plugs to super tune the engine", you might learn some things there you might use to diagnose your timing and fuel variables.
pete- the lift and big tires will hurt your mileage but it shouldnt be that much. my 6.9 with 3.55s and 285/75/16 gets 17 with no turbo... . but thats highway, offroading will me much different. do you have much smoke? it could be a timing issue, bad injectors? Pump turned way up?
I assume you have 4.10s with those big tires
I assume you have 4.10s with those big tires
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I see you have the big tires. Did you recalibrate the speedometer for those tires?
Thats what everyone is thinking that i have talked to is that it is a timing issue. The truck runs great, starts up instantly every morning and throughout the day. The pump is not turned up and has been rebuilt recently. I havnt ever replaced the injectors at all and i have had it 2 years i dont know if they were done before i got it. What is your guys advice on seeing if it is in time or what i should do about that. I reallly dont know where to start on timing one of these give me a small block chevy and we could do some business lol. these idi's are another breed.
quick speedo check: get a stopwatch, keep it steady at 60 on the highway. The time between the green milemarkers should be 60 seconds. Repeat a few times, and you should have a pretty accurate idea of speedo error.
I suspect something is actually wrong with your truck. My bus gets high 8's but its 10 feet tall and weighs 13,600 PBS dry, and its not turbo or overdrive. Your big tires should help you on the highway. What rpm are you turning at speed in top gear? Look for black smoke. Have the timming checked at an in or truck place. Bad injectors are possible, but I think you'd have smoke if that were the whole problem. Do passing semis blow you all over the road? Could there be a granny or alignment issue? Is the crankcase pressurized?
Kip on truckin'
I suspect something is actually wrong with your truck. My bus gets high 8's but its 10 feet tall and weighs 13,600 PBS dry, and its not turbo or overdrive. Your big tires should help you on the highway. What rpm are you turning at speed in top gear? Look for black smoke. Have the timming checked at an in or truck place. Bad injectors are possible, but I think you'd have smoke if that were the whole problem. Do passing semis blow you all over the road? Could there be a granny or alignment issue? Is the crankcase pressurized?
Kip on truckin'
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Wanabpete.........you can not accurately set the timing until the injector pop off has been set............if you are not running any more than about 10 PSI boost then setting the injector pop off at 1900-1950 PSI will be fine .......get them as "humanly possible" to the same pop off on each injector.......( a Huge trick to fuel mileage is that the injector Does Not Drip a Drop at just a few pounds under pop off pressure, if they drip, they are not clean or need to be replaced)
then set the timing.....(I do not agree with Fords timing speck, but that is a very long story)
make sure the thermostat maintains a top radiator hose temperature of 190-195°F.........
make sure the air pressure in the tires are at Max For the Tire/Load............
(then learn the glow plug reading method to change your driving habits for the best mileage)
crossbones
then set the timing.....(I do not agree with Fords timing speck, but that is a very long story)
make sure the thermostat maintains a top radiator hose temperature of 190-195°F.........
make sure the air pressure in the tires are at Max For the Tire/Load............
(then learn the glow plug reading method to change your driving habits for the best mileage)
crossbones
I just filled earlier and I am getting 14.6. I drive 55 miles a day to and from work, 60% of that is thru town. I tend to run a little heavy on the throttle (the straight pipe sounds good) and could probably get better if I drove a little less aggressive.
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I have a dually with the same engine setup, I get a constant 20 mpg now,when I drive both city and hwy, if it is just city only about 17.
I used to only get 10/12 city 14/15 hwy, that was long ago, 6+yrs ago
It took awhile for me to learn how to drive my truck and maintain it to get the better MPG, Im glad I have it now..
I used to only get 10/12 city 14/15 hwy, that was long ago, 6+yrs ago
It took awhile for me to learn how to drive my truck and maintain it to get the better MPG, Im glad I have it now..
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Did the mile post test and at 60MPH from post to post is 56 secconds every time
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If that's the case, then you are actually doing 64.3 MPH when your speedometer reads 60 MPH. For every 100 miles showing on your odometer you have actually gone 107 miles (approx). Multiply your speedometer reading by .07 and add that to it and you will have your actual speed. You may or may not be able to correct that with a new drive gear on the speedometer cable. Hope this is accurate as it has been a while since I've done these kind of calculations.
Did the mile post test and at 60MPH from post to post is 56 secconds every time
[/ QUOTE ]
If that's the case, then you are actually doing 64.3 MPH when your speedometer reads 60 MPH. For every 100 miles showing on your odometer you have actually gone 107 miles (approx). Multiply your speedometer reading by .07 and add that to it and you will have your actual speed. You may or may not be able to correct that with a new drive gear on the speedometer cable. Hope this is accurate as it has been a while since I've done these kind of calculations.
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