Crappy gas miliage

[Worx]

I know it been discussed before but my 03 4.3 is only getting 14mpg.:mad:

I have a PCM forless tune set to run on 93 & it runs good but the gas milage sucks bad,running around town with the ac on & I dont drive like grandma moses either.

I havent changed the plugs,cap or rotor becuase it runs very good & I just wanted to see what other people are getting in their 4.3's around town.....

Should I just do a tuneup & see if it gets better & what plugs do you recommend ??

[XTREME80]

My 03 Xtreme only does about 18 on a good day with moderate highway driving.

[Jongo88]

I get 15.3 all around on a good day....

[EricPts10]

Put a LSx in. You could about double your mileage.

[93_deuce]

My 93 CPI averages about 16-20. That's mostly city driving and a little highway to/from work. It's not really highway driving during rush hour(s) though!

[Nickelin'Dimer]

You think you've got reason to complain? My LN2 (4-cyl) '99, with the SFI & long intake runners, gets only 18.5avg... While my '94, equipped the same way, got 24.5! What's up with that!?

[SleeperSS]

I'm getting 23.5 with 222K...

[droopy89]

City, im happy to see 15, highway/city, i was about 19-20 before my tune

[Worx]

City, im happy to see 15, highway/city, i was about 19-20 before my tune

Sounds like we got the same tune.

I love how it runs but it sure sucks gas !!

[rentedmule]

A/C and a heavy foot is killing you. I have no idea what my tune is like (it's not stock) and I get 18 or higher in town and I've seen as high as 24 on the highway. I absolutely do drive like grandma though and only use the A/C maybe once a year. My mileage goes down in the winter when I'm running the defrost constantly.

[Worx]

A/C and a heavy foot is killing you. I have no idea what my tune is like (it's not stock) and I get 18 or higher in town and I've seen as high as 24 on the highway. I absolutely do drive like grandma though and only use the A/C maybe once a year. My mileage goes down in the winter when I'm running the defrost constantly.

Do you guys have ethanol in your gas ???

[rentedmule]

I did when I lived in Alberta and that's when I saw those mileage numbers. I was getting the same kind of numbers when I had the supercharger on too. Black-X on the other forum has done fuel economy dyno tunes on stock 4.3's and saw 4 mpg increases with no change in RWHP. It could just be that your tune is off.

[Jay-Sliver]

AC just sucks the life out of these trucks..

4mpg more on an economy tune with no loss in hp, sign me up!

Jay

[droopy89]

Mind you, my 15 city, is 1 mile to work, 1 mile home, barely has time to warm up..thats what kills mine..

[Worx]

We have to run ac here or sit in a sweat soaked seat.

What plugs should I use ? AC ??

[droopy89]

Im running NGK Iridiums, many others are as well, but either those or the AC iridiums are prolly your best bet imo

[XTREME80]

I would go Delco professional or NGK.

[csl2006]

wouldn't happen to have a k&n on there? My s10 used to get about 19mpg and for a couple week stretch it got 9-13mpg it varied on checks. I even drove it extra easy thinking I was at fault. I did a complete tune up no effect. Ended up the K&N after 3 years of it being on, the oil gummed up onto the MAF sensor and started throwing codes. I cleaned the MAF real good and instantly the MPG went up. The code was still on for the MAF but the MPG never went down after I cleaned it and ditched the K&N.

[King_Ice_flash]

Do you guys have ethanol in your gas ???
I get better mileage than 18MPG with e85.

[Worx]

I run a in the box K&N filter & clean it twice a year,maybe its time.

I use a very light coat of oil after reading on here about the MAF sensor but will check both those today.

[Worx]

Ok I pulled the filter & it was ready for a cleaning. I looked at the screen on the MAF sensor & it was clean.

Should I spray some kinnna cleaner thru it ???

[Heavy Chevy]

Ok I pulled the filter & it was ready for a cleaning. I looked at the screen on the MAF sensor & it was clean.

Should I spray some kinnna cleaner thru it ???
I would take the MAF sensor off and spray it with carb cleaner!

[rentedmule]

There's a specific cleaner for the MAF. you're not supposed to use carb cleaner for some reason that I don't remember.

[Worx]

I will look for MAF friendly spray

[Worx]

I went to Advance & got some CRC MAF sensor cleaner & some NGK Iridium plugs.

See if the mileage increases.....

['94 Benson]

im interested to see if those plugs work or not. my dad put a set of Iridium plugs on his silverado ( '07 4.3l) and he said it pulls so much better and even fixed his cruise control issue (it liked to kick down hard at speeds >65mph) and he said his mpg went up. i think he gets 23-24 out of his truck now (compared to 21-22 before). i only get 16 mixed city/highway.

[Worx]

I installed the plugs & cleaned the air filiter & MAF sensor.

Drove around & it feels a little better & the plugs looked original. I will fill it tomorrow & see what it gets....

[Worx]

Rained here all day today so no mileage tests.

[Heavy Chevy]

There's a specific cleaner for the MAF. you're not supposed to use carb cleaner for some reason that I don't remember.
Ooops, thanks for the info! I would hate to steer someone wrong!

[Worx]

Hey I saw your truck....NICE.

[XTREME80]

Speaking of mileage my engine swap 4WD truck got 16.5 mpg with allot of idle time on this last tank.

[spideyjected]

The Sierra gets 16 "all purpose" if I keep the foot out of it... Close to 20 on the highway obviouusly less around town and in 4 wheel drive

[Heavy Chevy]

I get 20/21 with mine, highway!

[Worx]

Update

I drove to Orlando (125 miles) running 80 mph with ac on & back running 85 + with no ac & it got 18.3 mpg.:cool:

Its good not to see the gas guage drop so fast & the ole truck (155,000 miles) runs like a champ. It will shoot right up to 100 with no problem.:hypnotize

[Worx]

Went to NY this past week towing a trailer with 3 skis & it got 15.

Dropped the trailer in NY & the best I got was 20.5 mpg with no AC.

[4runnerchevy]

9-11 mpg suckas, I am slowly, but surely draining those fuc#ers of their oil reserves.

['94 Benson]

got 10.8 mpg the other day, but that was pure city driving. i get 16.5 to 17.8 on an average tank. i also just replaced the plugs (which were already starting to get carbon build up) so maybe that will help a little.

[Nickelin'Dimer]

Drove my '99 LN2'd 'Noma out to my brother's early Easter-morning, holding it to just-about where it'd hold overdrive without downshifting, and running steady like that for miles. Ran 78 most of the way, touched 81 a few times... Even hit 83 once! only had to hit the binders twice (Damn robo-cop speed-traps!). The result: About 24mpg, I reckon'. That's the best I ever saw it get, and the first time I ever saw it get it!

[Brian_D]

mine gets around 12 as well....

wasn't to bad tho when gas wasn't so expensive.

[emillard]

94 4.3 SS here.

I'm glad I'm in good company. My truck is not a daily driver and I fill the tank full after only 50 or so miles of driving. (It stings less ya know?) With 100% pure city driving and going easy on the gas I'm at about 13.5mpg. I was rompin' on it pretty good a few tanks ago and got 11mpg in the city....ouch!!!! With some highway added in I get a whopping 17mpg. Oh and my engine is freshly tuned up as well.

I've got a 2011 Chrysler 300 with a 3.6L 295hp V6 that gets about 23mpg combined driving and will easily get 27mph on the interstate.

Technology sure has improved sine the days of the 4.3L

[disturban]

For those of you who are getting bad gas mileage but your truck runs good change your O2 sensors! Your O2 sensors will get lazy with age yet will not set off your CEL and they will cause bad gas mileage. This is a maintenance item and they should be replaced at 100k regardless if you have a CEL on or not!