I'm getting HORRIBLE gas mileage! Help me!

[r37ribution]

The software is a free download from the SCT like I posted above. I just happen to have a brand new cable ( extra ) that I need to sell ( its advertised in the FS forum ).

you have a message...

 

[Concept]

A follow up question.

I've run out of gas one time in this vehicle. Ever since the time I ran out of gas, the check engine light has remained on. That's even after getting a full tune up. Does this poor mileage have anything to do with the oxygen sensor or modulator under the car? I've got two under it. One near the gas tank and other towards the front. They're still hooked and all but I thought I'd ask anyhow.

Thank you everyone. So far, you've all been very nice and informative.

 

[dreamr]

If you have a CEL on then yes it is likely related to your poor mileage. And yes a bad o2 sensor could cause the problem, but I believe you have more than 2 .

And since I was whining about my mileage earlier I should elaborate on my weekend discovery. I checked my speedo against my GPS and it is still about 11% off after the EEC being re-tuned.
So I guess I should quite whining. My mileage is actually rather average at about 14-15 in city.

 

[r37ribution]

If you have a CEL on then yes it is likely related to your poor mileage. And yes a bad o2 sensor could cause the problem, but I believe you have more than 2 .

And since I was whining about my mileage earlier I should elaborate on my weekend discovery. I checked my speedo against my GPS and it is still about 11% off after the EEC being re-tuned.
So I guess I should quite whining. My mileage is actually rather average at about 14-15 in city.

Then get your EEC re-tuned for the larger tires?

 

[r37ribution]

which is exactly what i need to do...but first I need to buy the tuner, ahhh can't wait till Doug replies to my email

 

[dreamr]

Then get your EEC re-tuned for the larger tires?

I did, as well as for low gears, but apparently there was a minor mistake on my program. Not a big deal though, and in every other aspect the tunes are awesome!! I have been driving with a discrepancy for a long time (previous oversized tires), and now that I know it is there still, I'll adjust for it.

When I get around to having some head work done, or track down a new set of heads. I will have it corrected. For now I have the GPS if I need accuracy. I made it a point to compare the readings so I know what I am really doing in relation to my speedo. At 44 I am really doing 50, at 52 I am really doing 60, at 60 I am really doing 70. As to gas mileage figures. I rarely care to see the poor numbers, but if I get curious I add 11% to the miles traveled. Simple enough.

I am sure Doug would be willing to correct this for me, but like I said I'll wait till I have a need for re-tuning. A bit of speedo inaccuracy isn't worth bothering the guy yet again.

 

[r37ribution]

Yeah I hear ya, did he sent you the XCalibrator tuner or how did that work? I REALLY want this for Friday, I have never been to a dyno before and my truck needs it badly. I just bought Aldive's extra PC link cable so I can play around with my own program when I get the tuner. We musta posted at the EXACT same time, look at the post above yours...My milage is kinda crappy too, but then again I'm running 31" BFG tires so if my math is correct and the origional tires were 29" then I should be adding 6.45% to my milage? the odometer is reading approx 220 miles per tank so I'm getting somewhere around 234 mpg with a check engine light for the missing cat. Yet another reason for the tuner. It seems to be my cause for the bad milage, since when I clear the code the milage seems to get a lil better.

 

[terdrocket]

I get anywhere from 11.5 to 13.5mpg.
I just installed a new flux capacitor and it didn't show any gains.

 

[dreamr]

Yeah I hear ya, did he sent you the XCalibrator tuner or how did that work?

I have a SCT Micro tuner I purchased from Apten a year ago. Thankfully Doug appeared on the scene and reprogrammed it much to my pleasure. I love it. I believe Doug is out of town currently, but he has awesome customer service, so I am sure you will hear from him as soon as he returns.

 

[351wExplorer]

for some reason im only getting 8-10 mpgs

maybe its because of the 35s, or the 351w, or shoot maybe the gas suckin 650cfm edelbrock, shoot it could even be my heavy right foot

 

[r37ribution]

WOW you got a 351 in your truck? NIIIICE any pics?

 

[351wExplorer]

yeah theres a couple pics on a thread in here
351wexplorer

 

[flyboy777]

2000 5.0 Awd Mpg

I purchased mine 2 weeks ago and average 14 mpg around town and 18 mpg on the hwy.
Whats with all the horror stories of 10mpg?
I just had an XM installed and the installer has the same model and says 10 mpg as well.
My 92 4.0 was worse with 14 mpg hwy at best.

might as well be a mustang.

Matt

 

[monkeydude3]

1994 XL 4.0L OHV, 5 speed manual 4X2. I get 12mpg city. Sometimes I can push near 20 on the highway, but when I average it out the best I've seen is 16. It sucks. That's why this summer I'm sellin 'er to get somethin smaller. Anyone interested??? it's near perfect otherwise. It has been my guinea pig for my auto class so everything I could find wrong I fixed and it was all done by me (i know what the F I'm doin) also under the supervision of two ASE certified master technicians.

C-ya

George

 

[merc2dogs]

I get 15 - 17 in the city, and 21 - 23 on the highway, unless I keep my foot in it. 91 4.0, 373's, and normally a heavy load of tools in the back.
mileage was a little worse before I changed the gears from 327's

ken.

 

[r37ribution]

I purchased mine 2 weeks ago and average 14 mpg around town and 18 mpg on the hwy.
Whats with all the horror stories of 10mpg?
I just had an XM installed and the installer has the same model and says 10 mpg as well.
My 92 4.0 was worse with 14 mpg hwy at best.

might as well be a mustang.

Matt

I'm jealous, I get 11.5mpg in my '97 5.0 XLT no matter what city or highway
I do have a check engine light on for the EGR valve and I'm hoping when I fix that my milage will go up significantly... :crossesfingers:

 

[smcgee1979]

i just finished installing an engine today. ran it 50 miles and used a half tank. truck is 97 xlt 5.0 awd. no cel.

 

[Mbrooks420]

It probably didn't actually use a half tank. Did you fill it right before putting the motor in? Does it have raw fuel coming out of the tailpipe?

 

[r37ribution]

My 97 x had a bad hose going from the filler neck to the gas tank. It was leaking right out of the tube ever time I went up hill or even hit the gas hard! The design on the filler neck tube is much better on my 96 that thing ain't ever gonna leak.

 

[smcgee1979]

Yup I filled up and 10 miles later yanked the engine. Nothing that I can see outta the tail pipe, or whats left of it. I have to get a new tail end, it rusted right at the bend over the axle. The rest of the exhaust is solid though. Also I hear pressure releasing. maybe a bad pcv valve. When I shut the engine off you can hear the squeal. IF u take the oil filler cap off then shut the engine off, you don't hear anything. Tomorrow I will hit 100 miles and will be changing the oil, and im down to 1/4 tank already. Once I change the pcv valve and maybe illiminate the squeal it will get better.