1500 with really bad mpg, 10.5 avg
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Record Breaker
Joined: Aug 2008
Posts: 1,354
Likes: 1
From: stationed in nc
1500 with really bad mpg, 10.5 avg
Alright guys, im back over here trying to help my dad... he has an 05 w/4.7 leveling kit, 265 tires, cold air intake and flownaster exhaust.. nice truck..
He had his truck for a few years now.. everything else is still stock...
had champion plugs in it had .040 gap.. at best got 14 hyway, then he started to have a knock, did new plugs, ngk, ngk called the truck to have .046 gap, he put those in, and got even worse, around 11.2 hyway, he pulled the plugs put them at .040 like he had, and now only gets 10.5 hyway... also the truck had no power before (my stock 5.2 with 38's had more power) and for sure has nothing for power now... no misses or stalls.
Any idea what this could be? I mean my answer would be plugs, it started when he pjt them on but ngk is good stuff
P.s. sorry for any typos, I am on my pos phone
He had his truck for a few years now.. everything else is still stock...
had champion plugs in it had .040 gap.. at best got 14 hyway, then he started to have a knock, did new plugs, ngk, ngk called the truck to have .046 gap, he put those in, and got even worse, around 11.2 hyway, he pulled the plugs put them at .040 like he had, and now only gets 10.5 hyway... also the truck had no power before (my stock 5.2 with 38's had more power) and for sure has nothing for power now... no misses or stalls.
Any idea what this could be? I mean my answer would be plugs, it started when he pjt them on but ngk is good stuff
P.s. sorry for any typos, I am on my pos phone
Hall Of Fame
Joined: Mar 2009
Posts: 19,168
Likes: 23
From: South GA
Its likely mostly due to the FM exh. Its not the muffler itself causing the issue but what it was when i had my FM was I learned how to hold the gad pedal just right to make it sound off and that caused me to burn more gas.
Other than what you mentioned though, IDK if I would have done NGK. Champion is what came with the truck. Not NGK.
But winter blend fuels always get less. Anything with Ethanol get less. Poor air pressure in the tires, bad air filter doesnt help. Try also cleaning the back side of the throttle body and running some good fuel injector cleaner through it a few times.
Other than what you mentioned though, IDK if I would have done NGK. Champion is what came with the truck. Not NGK.
But winter blend fuels always get less. Anything with Ethanol get less. Poor air pressure in the tires, bad air filter doesnt help. Try also cleaning the back side of the throttle body and running some good fuel injector cleaner through it a few times.
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Record Breaker
Joined: Aug 2008
Posts: 1,354
Likes: 1
From: stationed in nc
Well the exhaust he doesn't make sound good, it is a winter truck right now, he's in upstate ny.. he just &dryer tires put on, all at 38 psi.. he just put the new aircleaner on it.. but ill let him know about the back side of the tb
Veteran
Joined: Aug 2009
Posts: 266
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From: Kansas
So you guys are saying the plugs can cause bad mileage? I put diamond fire plugs in mine and it has terrible mileage 12-14 14 is highway only driving. best I ever got was 15 so far. Worst was 8 pulling 6x8 trailer with 2 quads on it to OK on the interstate..
I would think these little 4.7L motors would get 20 easy.. but not mine.
I would think these little 4.7L motors would get 20 easy.. but not mine.