Crazy MPG in a V8

[mobeious]

i have a 2004 v8 only performance mod i have is the airbox mod i recently noticed im at the gas station more then my house lol .. i ran my truck to dead ass empty and put exactly 20.8gallons of gas in it and tracked how many miles i get off that i was shocked.. i ran 231miles off that tank thats 11 miles to the gallon and i travel on HWY 90% of the time i rarely drive my trunk in town WTH is wrong with my truck

 

[CALDWELL]

what were you getting before the airbox mod ?

 

[MikeyLikeIt]

How fast on the highway?

 

[mobeious]

what were you getting before the airbox mod ?

over 300 prolly 350 or so

How fast on the highway?

65-75mph

 

[n.gardner]

Dude i get 11 mpg with a V6 and 285s
thats normal

 

[lynchy wa]

I lost 1 mpg after my air box mod but got it back and then some after my tune.

 

[FarmTruk]

Has your local station recently switched to "winter-blend" gasoline?

That can account for a 1-2 mpg decrease by itself.

 

[perkinsbrandon72]

the same thing is happening to my truck i always am putting gas in it i get about 240 to a tank when i use to get like 350

 

[matt0248]

Clean teh trottle body and MAF sensor, disconnect teh battery for 10 minutes (or while cleaning the parts) and see what happens. When was the last time the fuel filter and spark plugs were changed?

 

[Limited02]

I am going to run this tank out and see where I am. I was currently getting around 300-330 myself(50% hwy/city) and just recently hit 270ish. Only thing I figured was winter blends as mentioned above.

Hoping to add a CAI and put the efan back on to see if there's a change. It'll be a short while though.

Also do what Matt mentioned, if it hasn't been tuned up in a while, that'll be a good start.

 

[MikeyLikeIt]

The winter blends kill my gas mileage along with the extreme cold weather. I normally get low 18 - 22 in the summer, but in the winter I am 14 - 18. 75% Highway, 25% around town.

 

[Inspector13]

The winter blends kill my gas mileage along with the extreme cold weather. I normally get low 18 - 22 in the summer, but in the winter I am 14 - 18. 75% Highway, 25% around town.

Same here. Was talking to a local guy about running E85. Worried about MPG loss running and he said that running synthetic oil and one heat range hotter spark plugs will result in no loss of MPG. He drives a Dodge Caravan though. Any one here try it?? Also what would one heat range hotter be for our 4.0's??

 

[Limited02]

Same here. Was talking to a local guy about running E85. Worried about MPG loss running and he said that running synthetic oil and one heat range hotter spark plugs will result in no loss of MPG. He drives a Dodge Caravan though. Any one here try it?? Also what would one heat range hotter be for our 4.0's??

Read through some of these threads about E85-

http://www.svtperformance.com/forums/distillery-374/

 

[FarmTruk]

The winter blends kill my gas mileage along with the extreme cold weather...

A good point as you mentioned above, another cause of cold weather mpg drops is the fact that it simply takes longer to warm the engine at 20* than 90*. On my drive to work I barely get it out of the richer running "open loop".

This is more noticable if you primarily drive city/short trips than long highway drives. But it still affects mpg.

 

[CALDWELL]

^ couldnt agree more...

I do all city driving, and my longest trip to work is only like 5-7 miles from my house...

 

[donlightbody]

more air = more gas to keep that ratio the computer loves

 

[Elessar65]

I have a 98 SOHC, 32s, 4.10s, CAI, and Catback. I'm happy if I get 200 out of my 17 gal tank. Usually I get to about 160 before I fill it up (but I refuse to let it fall below 1/4 tank). But its mostly cause 98% of my driving is in town, and my truck never has a chance to warm up. I live like a 3 min drive from work. 1.5 min if I hit the lights green. Back when I drove 20 min to work everyday in the summer I was getting like 17mpg.

Its always worse in the winter, either due to the winter blend fuel, running in open loop til its warm, or cause it sits in your driveway warming up for 10 min every morning.

 

[JonSwift]

i have a 2004 v8 .. i ran my truck to dead ass empty and put exactly 20.8gallons of gas in it and tracked how many miles i get off that i was shocked.. i ran 231miles off that tank thats 11 miles to the gallon and i travel on HWY 90% of the time i rarely drive my trunk in town WTH is wrong with my truck

Similar situation for me a few months back. Among other things, I used Seafoam, replaced the PVC valve, replaced the fuel filter, replaced an O2 sensor, and cleaned the MAF. I was kind of diagnosing the problem as I went along, but at least one of the above seems to have done the trick. I was getting - on average - 21 MPG on the highway, maybe more [after I fixed it: before the fix, it was 12 mph, and worse, plus rough going]. Driving a V6, @ speed limit 55-60 mph, easy on braking/accelerating, etc.

The biggest, most easily gained improvement I saw in my Explorer's performance was after I Seafoamed her. [Used the vacuum line before the PVC valve, to make sure all 6 cylinders were treated]. It ran disturbingly smooth after. Maybe you ought to give it a try if you haven't already? It might just be built-up crud in your engine.

 

[safn1949]

Read through some of these threads about E85-

http://www.svtperformance.com/forums/distillery-374/

I read it and I question this guys opinion very much,he is gung ho for Ethanol and contradicts most of the science I have seen on it.

 

[Inspector13]

So does anybody know the part number for a one heat range hotter then factory spark plug for the 4.0 V6 is?? I'll give it a shot and see if it's true or not.