metalmechanic

anybody getting better mileage, mine has gone to ****

Swift_01_z-28

iTrader: (1)

Yeah, it's gonna do that until you get it tuned. It'll prolly continue to be crappy after the tune, just depends on how you get it tuned. The headers and exhaust are making it run rich.

GO BABY GO

iTrader: (15)

After i put mine on I reset my fuel trims and the car got amazing gas mileage. I used hp tuners

shaun

my car picked up some mpg you just need a good tune.

metalmechanic

well its been tuned and runs great, my tuner is a tech at gm dealer and drags his own f body, he mainly adjusted the timing, and idle rpm, im guessing its a trade off

ChocoTaco369

I put my headers and switched from 2.73's to 3.42's at the same time. My mileage only dropped about 1 mpg, so I'm willing to estimate that was more due to the 3.42's than the headers. Essentially, my headers didn't do anything to my mileage.

What really hurt my mileage was my dynotune. I picked up almost 40rwhp from the tune, but I lost 1-2 mpg. That really upset me as I was expecting to get better mileage, not worse

20ws601

check for exhaust leaks those will kill your mpg

Badguy7

iTrader: (6)

yea my gas mileage has gone to crap as well.

nemss1

its recommended to get a tune with LTs. this will fix the horrible gas mileage problem

udienow

iTrader: (18)

I never got a tune after headers, I averaged about 17-19MPG mostly city... which wasnt much different from before i did the headers.
Are you guys talking about a dyno tune after headers? I cant really justify $400 bucks for that just for a few MPGs and a few HP/TQ.

9000th01ss

iTrader: (10)

I've got two camaros with headers, one has no tuning for the headers and got 27 mpg on a road trip.
On the other car the O2's started switching slow which sets a insufficient switching code, which puts your car in Open Loop and rich.
Most tuners know about LT's and this code and turn it off. The O2's can switch slow, but with the code turned off won't stick it in OL all the time.
I turned that code off and the MPG's went back to normal.

metalmechanic

my motor is stock LS 1,LS 6 Intake with kooks lt,s , high flow cats, kooks y and dumped straight out the back, my plugs are gapped at .040, ????????????

9000th01ss

iTrader: (10)

Plug gap is too small IMO.

SOOO.......hows the switching on the O2's looking? Have you scanned to check?

Of course you could do what most people do and replace good O2's with new O2's without checking, and when the new ones make no difference be all discouraged thinking the car is a gas hog.

Internet people can guess at whats wrong, it's up to you to do the hands on and find out.

jmilz28

iTrader: (13)

AMEN!! You need a tune, period. Headers with a tune will improve MPG...IF...you keep your foot out of it. Most of us "test out the sound" of the new headers a lot, which kills mileage all by itself. Keep your foot out of it, get a tune, clean your air filter, and you will see small but noticeable improvement. Get a new fuel filter too.

FYI, I have seen headers improve MPG without a tune and hurt. Depends on how off the factory tune is. I've seen factory tunes rich (most are) but some lean. I've seen headers cause a stock tuned car run richer and leaner, go figure. Anyway, point is, get a tune. FYI also, if you have cats and are running rich, your cats will die sooner.

Good luck,
J

jmilz28

iTrader: (13)

If you can' justify it, you either aren't paying attention or have the wrong hobby. You will pick up MPG (assuming your foot doesn't get heavier) and HP with a good tune, bet on it.