MR WESST 02

i used to get almost 400 miles to a tank before i did this install. literally the ONLY things that have changed besides the longtubes and y pipe are the rotors. i also have slp loudmouth. possibly because theres no back pressure? but ive never heard of that ruining gas mileage. at first i assumed because i got on it more and drove like more of an ***. but its been a few weeks and ive been driving like a grandma most places but its just bad. i put about 100 miles on it today and that was about a half tank of gas. any ideas? thanks.

sandsk8erz400

iTrader: (1)

Have you had it tuned?

bayer-z28

iTrader: (14)

FWIH, you need to have it tuned because they are flowing more and the O2's pick up on this an compensate by adding fuel. -Erroneously, but still. Some LT swaps aren't bad but it depends on the car. I was getting 400mi (HW) to a tank on my h/c LS6 intake in optimal conditions, so it'll come back.

TImmy_Jones

iTrader: (4)

Bad o2 sensors would cause erratic fueling and bad mileage.

cookba

iTrader: (10)

all of the above is correct. also you may want to get it tuned before you burn up the O2 sensors from running too rich.

BOBS99SS

iTrader: (2)

Mine did the same thing my buddy hooked it up to hp tuners and the issue was solved,it ran great for a bolt on car after he tuned it

thunderstruck507

iTrader: (18)

1) you need a tune
2) you could have a bad o2 sensor
3) for best results figure MPG, miles per tank is about useless and GM fuel gauges are not accurate by any stretch of the definition

sscamaroburn02

iTrader: (14)

yep needs tuned and check the O2's. Also, 400 miles to a tank is pretty darn good. Good luck!

PheonixLS1

iTrader: (4)

No kidding, I only got 275-300 on a tank stock

Full-Force

iTrader: (11)

Hook a wideband up to your car and check it. Unless o2's are not working right it will be 14.7:1. The PCM will adjust for that. That's what fuel trims are for. Just because it adding fuel doesn't mean its running rich. If its adding then it needs to be adding.

There is no reason you should not be running at 14.7 during closed loop.

TImmy_Jones

iTrader: (4)

Doesn't need a tune! There is something else wrong. Yes a tune will net you some power, but will not fix 15mpgs. Something is wrong.

MR WESST 02

Its never been tuned and im running 02 simulators in the downsteam 02s. i do have an air to fuel gauge as well. right after i installed that stuff when i would have it floored it read the same as it did before lt's, it would go one notch into rich. its been doing that until the other day, when i get on it it will go 3 or 4 notches into rich. and when i was getting around 400 to a tank. it was all highway and probably going about 85-95

Hard Core Z28

Check your plugs. Might be fouled or even cracked.

intenseblue

iTrader: (1)

[QUOTE=thunderstruck507;14745501]1) you need a tune
2) you could have a bad o2 sensor
3) for best results figure MPG, miles per tank is about useless and GM fuel gauges are not accurate by any stretch of the definition[/QUOTE

Points one and two are 100% correct


As for point three... this is I how I do it. I use a local BP station and fill up at the same pump nearly every time. Fill up, set your trip and the NEXT time you fill up divide the miles by the gas it took to cap it off again. Screw the guage.

TImmy_Jones

iTrader: (4)

Any codes? Does the car misfire or backfire? Visually inspect the plug wires...if not I think bad O2 sensor.


Sorry, unless you have a wideband O2 sensor, those narrowbands are just a light show.

99monguse

Comeon dude...400mpt at 85-95mph. I think you're stretching the truth a bit.

thunderstruck507

iTrader: (18)

Clean you MAF sensor. Likely has trash on it.

Check for vacuum/exhaust leaks, 02 sensors could be seeing clean air and dumping fuel

Scan the car for codes.

Check MPG as posted above: fill up/top off, reset trip meter, drive (preferably all highway), return to same pump (for best results, but any pump can suffice), fill up/top off, divide miles traveled by gallons used

Miles per tank= crapshoot, bullshit numbers based on guessing unless you run your tank bone dry

black00ssFL

iTrader: (24)

As said it could be a couple things, not directly related to the longtubes (and isn't imo)

exhaust leak near O2 sensor, making it see "fresh" air and add more fuel
vacuum leak allowing in unmetered air
Bad O2
Your right foot after new mods

MR WESST 02

ive been throwing one code for the air pump, which i took out when i did my headers. but when i clear it it doesnt comeback for a while. both my 02s were good before the install and i know theyre in there nice and tight. ill get my buddy to plug in scanner to actually read the 02s. i had a misfire a couple weeks ago but one of the plug wires came off but when i fixed it i made sure all the other ones were on all the way. and about the 400mpt it was like 380 something, but still.

nmass399

It needs a tune, the maf has to be calibrated for the the right amount of airflow into the engine. You have to do this with a wideband, stock 02's are not accurate. And get someone to tune it that know's what they are doing, not just Billy bob that has hp tuners and such that lives two blocks over lol.