89 Terrible MPG!!!
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New User
Joined: Jun 2012
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From: Minnesota
89 Terrible MPG!!!
I have an 89 F150 302 auto with 33s and im getting 8MPG!!!!
Its a project...rear cat is removed (i guess it had 2??) and no muffler. bought it like this cheap to make into a hunting rig. also, the manifolds are both cracked... would those things make it that bad? I can get better MPG with a v10!!! I dont know where to start
Its a project...rear cat is removed (i guess it had 2??) and no muffler. bought it like this cheap to make into a hunting rig. also, the manifolds are both cracked... would those things make it that bad? I can get better MPG with a v10!!! I dont know where to start
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
Stock tires on that rig were 28.5" tall so your speedo is way off and therefore so is your milage guesstimate.. assuming you're using the odometer to calculate milage and not the fuel gauge... which is typically so inaccurate it's laughable.
What gears does the truck have?
Is it dual or single tank? If dual do they both work and if yes do you get the same milage on both tanks?
What gears does the truck have?
Is it dual or single tank? If dual do they both work and if yes do you get the same milage on both tanks?
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New User
Joined: Jun 2012
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From: Minnesota
i dont remember off hand on the gears. only code is from the rear cat being gone. and i have the rear tank removed... doing a tune up this week. thinking of headers and duals with a balance h-pipe night help some?? that will delete the other cat...
Posting Guru
Joined: Jul 2009
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From: Toledo, Ohio
Probably normal due to your gearing and tire selection. I get 9 in my truck. People have pushed and pushed and pushed on that tire size vs odo deal and I can state with 100% accuracy that is not the case.
Switching to different tires will increase the mileage, but according to factory these trucks sucked on fuel anyway. Only looking at about 14 or so.
However, one thing you did not mention, is it a 4x4 or not?
Switching to different tires will increase the mileage, but according to factory these trucks sucked on fuel anyway. Only looking at about 14 or so.
However, one thing you did not mention, is it a 4x4 or not?
Postmaster
Joined: May 2003
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From: E.Lincoln County, NC
Maybe I don't understand your statement.
Senior User
Joined: Apr 2012
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From: Fort Worth, Texas
There was another mpg thread going around not long ago and it got me to checking my fuel economy. Mine gets 11.5 mpg with no mods to the motor. I have a 300 six with an E40D and the highway gears (2.70 something I believe) in the rear end. I have 31x10.50 tires. I do however run a bottle of Valvoline complete fuel system cleaner in both tanks every oil change. I change my oil religiously every 3000-3500 miles for the last 17 years in this truck.
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FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
You guys in the states write this off as insignificant because your scale of measurement.. the mile and the gallon are so large that the losses appear to be small. In places that use the metric system the units of measure are much smaller(kilometer and liter) so there is more resolution and therefore the differenes are easier to see. But regardless the fact is larger tires make the speedo read low so you unknowingly drive faster which consumes more fuel, and at the same time the odometer racks up less distance than you actually covered so there are two factors impacting fuel consumption and the combined effect is double what you think it is, and that is significant.
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FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
Try driving the truck on the highway in D not OD.. especially in hilly terrain and windy conditions, you should see a healthy increase in milage.
Postmaster
Joined: May 2003
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From: E.Lincoln County, NC
But regardless the fact is larger tires make the speedo read low so you unknowingly drive faster which consumes more fuel, and at the same time the odometer racks up less distance than you actually covered so there are two factors impacting fuel consumption and the combined effect is double what you think it is, ......
Really? My Sport Trac has one a slightly larger tire than came on it and the speedo reads slow so believe it or not I actually drive a few MPH slower ...... so I don't gather speeding tickets. I doubt I'm the only American who can figure this out.
There are just many variables that can determine MPG so they term YMMV really does apply here!
Lead Driver
Joined: Jul 2007
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From: Rhode Island
Better check that code again. The EEC-IV system in your truck cannot monitor the cat, and won't care or know if it's gone.
Posting Guru
Joined: Jul 2009
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From: Toledo, Ohio
Ok, I apologize and I should rephrase it... As I am not sure what 'cam' is using to calculate his mileage, I have proved the low mileage is caused not by watching what my odometer reads, but by the actual distance I am driving.
The reason I said the tire size vs odo argument is not the case is because I myself checked it even after Conanski stated before that I was actually reading it wrong due to my change in tire size. I only threw that possibility out because I would assume the OP has calculated that sort of logic before posting. Also seeing as to how he has 33's and did not state the gearing, I could only guess that the reason he is getting such poor mileage is indeed because of his gearing. Especially if his truck has a C6 trans which lacks an overdrive gear..
The reason I said the tire size vs odo argument is not the case is because I myself checked it even after Conanski stated before that I was actually reading it wrong due to my change in tire size. I only threw that possibility out because I would assume the OP has calculated that sort of logic before posting. Also seeing as to how he has 33's and did not state the gearing, I could only guess that the reason he is getting such poor mileage is indeed because of his gearing. Especially if his truck has a C6 trans which lacks an overdrive gear..
Postmaster
Joined: May 2003
Posts: 3,310
Likes: 9
From: E.Lincoln County, NC
No apology needed, just picking at you.
Always heard the top 3 things a man will lie about are income, MPG and their love life.
Don't worry about me lying ......... all of mine are bad!
Always heard the top 3 things a man will lie about are income, MPG and their love life.
Don't worry about me lying ......... all of mine are bad!
Thread Starter
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New User
Joined: Jun 2012
Posts: 12
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From: Minnesota
Probably normal due to your gearing and tire selection. I get 9 in my truck. People have pushed and pushed and pushed on that tire size vs odo deal and I can state with 100% accuracy that is not the case.
Switching to different tires will increase the mileage, but according to factory these trucks sucked on fuel anyway. Only looking at about 14 or so.
However, one thing you did not mention, is it a 4x4 or not?
Switching to different tires will increase the mileage, but according to factory these trucks sucked on fuel anyway. Only looking at about 14 or so.
However, one thing you did not mention, is it a 4x4 or not?