Why is my mileage so low?

GRGT1994 · Sep 15, 2005

I just filled up. And I am getting less than 14 miles per gallon now (like 13.5). WTF? See my sig for mods.

I have the timing dialed in as suggested by Trickflow and Anderson Ford. It runs like a beast now. But still I get this horrible mileage. And I read these posts from others with HCI setups saying they get close to 20 mpg (maybe they guys never corrected their speedos for aftermarket gears???).

Anyone else getting really bad mileage? Any ideas what might be my issue, or what I should look for?

S/CBlack95GT · Sep 15, 2005

What kind of driving do you do? Lots of stop light to stop light? I only get about 13-16 in town, but around 23-24 on the highway.

Pokageek · Sep 15, 2005

I have done a lot of in town lately and getting 15.5 mpg.

mo_dingo · Sep 15, 2005

stay off of the go pedal.....that helps....lol

RIO5.0 · Sep 15, 2005

I look at your sig and say...you wanna play, you gotta pay....more power means more petro....no way around it....
I mean look at the mods and your gears....Those ain't MPG gears....

I'll throw this out for what its worth....you running an oil separator?? I added one and gained some MPG right off....mine was woofing alot of oil and it musta had an affect on my milage..I emptied the separator 3 times in 1200 miles....so it was drinking its share of two stoke mix shall we say...
I havent even thrown a timing light or nada to it since pulling it outta storage this Spring, just drove it...Chit I got 2 YR old NGKs' in it....only thing it got this year has been 2 oil changes...
If i drive it calmly, 18-20...if i drive it normal...prolly 16...

CManT1914 · Sep 15, 2005

I got 16 the first tank, and then 13 (big exhaust leak). Fixed it, and I got 14.6 on the last tank, but I was hot-rodding it around quite a bit. This is with no real tuning, other than maf transfer and injectors.

Al J · Sep 16, 2005

Check the tire pressure---small thing, but made a 2 miles per gallon difference for me cuz of soft front tire.

MisterCMK · Sep 16, 2005

The further you push on the gas pedal, the faster the gas gauge drops. Words to live be.

AaronG · Oct 4, 2005

Well, if nothing else you could check some obvious things. Make sure you air filter is clean, tire pressure, how's your alignment? Maybe you need to replace an 02 sensor. I corrected all of these things on my car and picked up some mpgs. They add up.

Kevin R. · Oct 4, 2005

Check and see if you have a 5.0 under the hood.

I think that's my problem.

MisterCMK · Oct 4, 2005

I actually just got 25.22 mpg on the interstate, from Minneapolis to Fargo while doing 75mph. Not too shabby. I'm shooting for getting 26 or 27, hopefully 28 when I take a trip a little later in october on some 55mph highways.

balderman · Oct 4, 2005

I have never gotten 20 mpg in my car, even when it was stock.. I have a 345 FMS crate motor and I get about 15 mpg and thats when I baby it...

meyers2211 · Oct 4, 2005

your 4.10's change your overdrive gear to like above 2500rpms which is why your sucking down fuel

i'm getting about 14mpg

Zero Signal · Oct 4, 2005

I was getting close to 20mpg with a tune before putting on the Explorer intake. I think it's becuase the EGR isn't hooked up though. Now I get about 10mpg.

DFG 5OH · Oct 4, 2005

RIO5.0 said:
I mean look at the mods and your gears....Those ain't MPG gears....

i agree...4.10's a T-5 and a good H/C/I...i'd be happy with 14

chirs · Oct 6, 2005

Ever think that your speedo may be off. Tire size as well as gears throw of the speedo. Taller the tire, the faster it spins at a given speed. So that could throw of you mpg. Try this, go on the interstate and watch your speedo. Start at one mile marker and see how much your mileage goes up by the next mile marker. Mine only does .7 per mile marker. So, this means, assuming that the mile markers are correct, that my speedo is reading 30% less than what it is supposed to. I am running 275/55/17 tires which are bigger than stock. So you can see that while i only get around 20ish on the highway, with windows up doing 70 with cruise control, im closer to 26.

doobsstang · Oct 6, 2005

Where in GA chirs? Close to Augusta?

meyers2211 · Oct 6, 2005

My smog pump is clamped shut, what is the difference b/t that and an egr

CManT1914 · Oct 6, 2005

meyers2211 said:
My smog pump is clamped shut, what is the difference b/t that and an egr

Smog and EGR have no relation. Two completely seperate systems, one should not effect the other.

Smog pumps air into the catalytic converters to help burn the leftover fuel in the exhaust.

EGR takes exhaust gas and recirculates it through the engine to help cool combustion temperatures (exhaust gas is roughly 600* vs. combustion temps of 2000*).

Two seperate systems.

GRGT1994 · Oct 7, 2005

chirs said:
Ever think that your speedo may be off.

Thanks for the thread revival Chirs. My speedo is reading fewer miles than I am driving. I tested in on highway mile markers (10 miles for accuracy) after I installed my Speed Cal. But it reads within 1% to 2% of dead on.

I know the 4.10's aren't gonna get me into the Sierra Club, but when I read posts like the one from John getting 20 mpg and Zero Signal getting 25 or more I wonder WTF? Are those guys talking about their Prius, or are their speedo's off.

Why is my mileage so low?

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