# Gas Mileage Issues..
**URL:** https://forums.speedlife.net/t/gas-mileage-issues/248494
**Category:** Shift518 Automotive
**Created:** [November 19, 2009, 4:26pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494 "2009-11-19T16:26:30Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@99Blackex](https://forums.speedlife.net/u/99Blackex)
#### Post date: [November 19, 2009, 4:26pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/1 "2009-11-19T16:26:30Z")
I recently just put my beater truck on the road and I have started taking it out to work this week. However Im less fuel mileage than what I was expecting to get. The truck is a 92 Chevy C1500 with the 305, 5sp 2wd and it has 3:08 gears. Now I expected to get somewhere around 18-19mpg but my last tank full netted me 16mpg and I just filled up again tonight and calculated 14mpg. I do understand being an older vehicle and possibly being affected by the 10% ethanol. But it sure seems low to me. I put new plugs, wires, cap and rotor in. As well as a new air filter. It also has new tires with proper inflation. Thats what has me wondering what is making it get such shitty mileage. I’ve even been driving slower, setting the cruise at 70. The only thing that I can think of that could be cauing this is… if my fuel filter is clogged or the catylitic converter is clogged.
The check engine light comes on at random too. And I mean its totally random. I can go a whole day without it popping on but then the next day it does. I have only been able to narrow it down to the fact that it only comes on while Im at highway speeds and once I turn the engine off and go to restart, the light goes out. If I do any kind of city driving its fine. However, the truck doesnt seem to be running shitty… Just a random cel and shityy mileage.
Any suggestions would be appreciated.
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### Author:  [@GATVILLE](https://forums.speedlife.net/u/GATVILLE)
#### Post date: [November 19, 2009, 4:49pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/2 "2009-11-19T16:49:09Z")
the 98 silverado i had was the 305 and only got like 15mpg according to prev owner although i didnt drive it enough to find out exactly
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### Author:  [@psi2high](https://forums.speedlife.net/u/psi2high)
#### Post date: [November 19, 2009, 4:56pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/3 "2009-11-19T16:56:57Z")
Yea I had a 4.3 in my full size and it only got like 17 on a good day
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### Author:  [@usmc2801](https://forums.speedlife.net/u/usmc2801)
#### Post date: [November 19, 2009, 5:10pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/4 "2009-11-19T17:10:14Z")
That seems like descent gas mileage for that truck…but maybe an O2 sensor is going bad???
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### Author:  [@6SPD\_S4](https://forums.speedlife.net/u/6SPD_S4)
#### Post date: [November 19, 2009, 6:33pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/5 "2009-11-19T18:33:43Z")
Seems about right
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### Author:  [@JClark](https://forums.speedlife.net/u/JClark)
#### Post date: [November 19, 2009, 7:06pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/6 "2009-11-19T19:06:51Z")
Got me beat by 2mpg.
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### Author:  [@dubnix](https://forums.speedlife.net/u/dubnix)
#### Post date: [November 19, 2009, 8:22pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/7 "2009-11-19T20:22:39Z")
Yea dude. sounds like the o2 is going bad.All that heat we put on that exhaust mani stud to get it out ,most likely did it.
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### Author:  [@indy440](https://forums.speedlife.net/u/indy440)
#### Post date: [November 20, 2009, 4:02am UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/8 "2009-11-20T04:02:09Z")
14-16mpg doesnt sound too bad really. Swap out your o2 sensor and see what happens, you might do a little better.
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### Author:  [@freakLS7](https://forums.speedlife.net/u/freakLS7)
#### Post date: [November 20, 2009, 4:44am UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/9 "2009-11-20T04:44:28Z")
damn im getting 19/22mpg in my full size! :banana
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### Author:  [@underboosted](https://forums.speedlife.net/u/underboosted)
#### Post date: [November 20, 2009, 4:49am UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/10 "2009-11-20T04:49:08Z")
My 94 silvarado got 10 mpg. Yours sounds about right
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### Author:  [@indy440](https://forums.speedlife.net/u/indy440)
#### Post date: [November 20, 2009, 5:18am UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/11 "2009-11-20T05:18:28Z")
> [@FS:Lambo door hinges](https://forums.speedlife.net/t/fs-lambo-door-hinges/26117/8):
>
> damn im getting 19/22mpg in my full size! :banana
diesel FTW
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### Author:  [@KrazyKid](https://forums.speedlife.net/u/KrazyKid)
#### Post date: [November 20, 2009, 5:57am UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/12 "2009-11-20T05:57:35Z")
Guys, my H2 daily is only getting 9mpg city and 12 highway? I dont understand it. Is it my 26" 120lb wheels and tires, or the 450lbs of speakers in the back?
JK, man.
My buddy has the same truck, and when I borrowed it to get my sled last yet… it only got about 12mpg. half city/country crap roads & half highway. See if you can catch the CEL and scan it, it is doesnt stick in memory on the ecu. O2 could be bad like mentioned, and riching up the mixture maybe. Cut the cats off and run it straight piped. 94 you dont have to worry about it inspection wise right? Both my beater cars got major exhaust leaks, as in cat back fell off when I hit shit. Both cars picked up 2mpg on the highway.
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### Author:  [@dubnix](https://forums.speedlife.net/u/dubnix)
#### Post date: [November 20, 2009, 7:02am UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/13 "2009-11-20T07:02:13Z")
> [@OK, bought a ext. CD drive/burner](https://forums.speedlife.net/t/ok-bought-a-ext-cd-drive-burner/26124/8):
>
> diesel FTW
Duramax swap will be next
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### Author:  [@99Blackex](https://forums.speedlife.net/u/99Blackex)
#### Post date: [November 20, 2009, 3:49pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/14 "2009-11-20T15:49:26Z")
> [@Awesome time waster flash game](https://forums.speedlife.net/t/awesome-time-waster-flash-game/26107/12):
>
> Duramax swap will be next
I wish… But I did pick up a new O2 sensor from napa tonight. It was 22 bucks. Gonna throw that in this weekend and see what it does.
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### Author:  [@88slowmarro](https://forums.speedlife.net/u/88slowmarro)
#### Post date: [November 20, 2009, 3:59pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/15 "2009-11-20T15:59:42Z")
it is runnin fine ,c.e.l will be a few things prolly o2 sensor or egr actin up .m.p.g sounds about right for that .my camaro is only gettin 10 per gal so feel my pain ,oh and its a race fuel /93 mix
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### Author:  [@99Blackex](https://forums.speedlife.net/u/99Blackex)
#### Post date: [November 20, 2009, 5:39pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/16 "2009-11-20T17:39:56Z")
well im gonna put the O2 in and Dubnix has a egr valve off his old 350tbi that im gonna put in and see what that nets me. If it doesnt help, then oh well… I’ll just deal with it I guess. Just thought I would be getting a little better than 14mpg.
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### Author:  [@88slowmarro](https://forums.speedlife.net/u/88slowmarro)
#### Post date: [November 20, 2009, 5:45pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/17 "2009-11-20T17:45:06Z")
not really, gas mileage is on par for what it is .best bet is to just block the egr vacuum line as most of the time the ports in the intake are plugged and thats why it acts up .but def install o2 sensor as it will help a little
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### Author:  [@PJB](https://forums.speedlife.net/u/PJB)
#### Post date: [November 20, 2009, 5:48pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/18 "2009-11-20T17:48:31Z")
fullsize trucks are gas hogs, especially older ones.
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### Author:  [@99Blackex](https://forums.speedlife.net/u/99Blackex)
#### Post date: [November 20, 2009, 5:49pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/19 "2009-11-20T17:49:34Z")
Okay… I’ll see about doing that then. But if i blocked the vacum line, would it throw a code?
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### Author:  [@99Blackex](https://forums.speedlife.net/u/99Blackex)
#### Post date: [November 20, 2009, 5:51pm UTC](https://forums.speedlife.net/t/gas-mileage-issues/248494/20 "2009-11-20T17:51:40Z")
Well I knew it wouldnt be great on gas… But since my father had an f-150 at one time with the 4.6l and 3:08 gears, he got like 23mpg on the hwy with it. So I figured being that mine is a little older, I would expect somewhere around 18mpg
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