I know there are threads about gas mileage - but non-really talk about anything besides people saying they have good gas mileage and others saying they dont.

Well - i took note this weekend of my gas guage going from 3/4 tank to 1/2 tank with only making about 45 miles. Im guessing this is pretty bad.

Im not sure why i have such horrible gas mileage - i put my CATLYTIC converter back on to bring it back up - and that didnt help at all and im not sure hwat could be wrong.

If anyone has any adivce- ANY! i would love to hear it. PS - i never give more than i would say 3/4 throttle and thats not often, so its not because i just floor it all around. Is there something wrong that i need to have it go checked out - and if so where would i take it because i need to figure out something b/c 150 miles per tank is pretty damn ****ty to me when alot of people get like 250 and thats with a TURBO!

Thanks guys

 

with my aem cai kaikaze header and greddy exhaust...im getting about 200+ driving it hard every so often...now 45 miles is that on street or freeway...this weekend so far i prolly have a gallon left before half tank and im at 120 so mostly freeway miles...i say about 70 freeway and the rest street ...plus starting it like 20 times....so 45 for a 1/4 of a tank is about right...maybe you have a leak or your filter is dirty...

 

I average 310 per tank, but my only mod is the RRM short ram. Since you and I are in the same location, I doubt it's the gas you're buying.

You say you put the cat back on. Which one? You've got two, one attached to the stock headers and one on the outlet piping before the muffler. You'll need both to maintain a good gas burn, but I still think there might be more to it than that.

Put your stock headers, with cat, back on and check your mileage for a full tank. Drive the car the same way as before. If that helps, you're probably running too rich. Have you reset the ECU recently? If not, go ahead just for the fun of it.

Once you put both cats on, get your emmissions tested. It'll let you know if you're running really rich, or worse, really lean.

Take the car to Max Madsen in Downer's and see if Todd can work you in. They shouldn't bother you about your mods, and they might find a real problem that needs to be dealt with.

If you don't want to go to a dealer, have your oil and plugs changed, and check your tranny fluid level. Then make sure your brakes are OK. Sticky brakes can hold onto the drum and cause the motor to work harder for less.

My advice, seek professional (ie, dealer) help. If you aren't willing to do so, you may be out of luck.

 

Mike, still having problems huh?

If you really want to figure out what the problem is, do what Sailor said, put your stock header w/ the cat back on. This will tell you if it really is the header and from there you can decide if you want to keep the header or just get bad gas mileage.

I really don't know why you're getting such bas gas mileage, all i can really think of is that your right foot is kinda heavy but then again, my gas mileage doesn't change no matter how i drive the car (i always get 24 mpg plus or minus .3 mpg or so)

i havent really heard of a case where an exhaust modification would kill your gas mileage like that. do you recall when it REALLY went down? was it after you put on your headers? was it after you put on your cat? was it just like that maybe?

and even after you put the header back on and you still have bad gas mileage, do what sailor said, take it to Max Madsen. this problem could be worse than you think (knock on wood). So Mike, good luck and have fune trying to figure this thing out

 

really? .. how much d u get on a full tank? ... usually when its full it takes awhile for the dial to go down but as u hit half a tank it will go down faster. i always monitor my mileage, resetting the counter everytime i fill up and always waiting till i see the light turn on.. most i ever got was 250 (i didnt want to risk it and run out of gas) .. haha

 

I get about 200 miles on the first half of the tank, and only about 100 more till the light comes on. Worst tank I ran about 24mpg, and the best was on a roadtrip and I got 38.5mpg. I have a SRI, Headers, downpipe, Testpipe, Magnaflow axleback.... uh, and magnacore wires. Im not sure what else would lead to poor gasmilage, but with my mods I'd expect to be running closer to 22-24mpg while Im actually getting about 27+

 

whens the last time you change your air filter? engine motor oil?

 

I have a washable air filter so i wash it out every so often.

Also - im getting my oil changed in a few days bc thats when its scheduled to go in.

As for taking it to Mad Max - i didnt buy my car from them so i wouldnt be warrantied by them so im not sure if they would be able to help me or not.

 

well at this point you're not gonna be warrantied by many people, bud, so it might not really matter where you bring it in

...unless of course you're gonna do what sailor mentioned... takin' off your mods and replacing with OEM for inspection...

 

i doubt i would do that since i have a catback and it wouldnt be worth to take it off just to get it inspected.

i might just take it in to get a tune up and see what happens then.

 

if you are still under stock warranty... any mitsu dealer should take it.

 

see - i didnt buy it from a mitsu dealer - so i dont have that warranty.

 

well i got an axle back exhaust and the 2 breather filters instead of the intake, and i only get about 230 to a tank driving pretty hard.

this tank i took it easy (as in..i only got above 3k rpms twice) getting on the interstate only time. i kept it below 2.5k rpms almost the WHOLE time and i got about 250 til the 1/4 tank line. but once it hit that line for some reason my foot doesnt get off the floor...lol dunno why..i guess driving below 2.5k rpms ALL the time makes me go insane and i need to go fast! lol

 

are you using cheap gas? i only use 91+ octane now. 89 makes my cars injectors dirty and the thing gets the worst mileage ever.

 

see if the hose from your fpr to your intake manifold is damaged, loose, or disconnected. having the fpr open to the atmosphere gives 3 bar fuel pressure when it should only be around 2.5.

if you didn't bolt the header on in the correct tightening order, you might have an exhaust leak before the first o2. you might be able to hear it. that would cause it to run rich since the exhaust will be sucking in air causing a lean reading.

if your ebrake pulls up in less than 5 clicks, you can loosen it.

it's not about keeping it under 3k rpms, it's about throttle percentage. i can floor it to 3.5k all day and let off and have ****ty mileage. stay under and at 15% throttle more or less regardless of rpm and you should have pretty good fuel economy.