Ok, i know yall read my threads and post of real crappy gas, i mean like something 19-20 to the tank(or less) on FULL GAS. Something like a lil over 200miles a gallon all city, thats rx8 gas mileage. Anyways, my cars under warranty so I asked the mitsubishi service center for some help, I didnt show them my car, I was getting it washed and asked the guy "symptoms of bad gas". He told me a lead foot, and I told him I dont have one. He said 'well, theres all sort of symptoms out there", i said like... and he said 'well, you know alot... cant think of the top of my head, but when its finished washing, ill take a look at it for 80bucks diagnostic check. I was like "80bucks, wth?" Im under warranty, he said if you are than dont worry, but you do have an exhaust, so whats under the hood and I said nothing, stock (I have a SRI), he said, well ur warranty is probably gone because of the exhaust and if theres intake, your warranty will be voided, and i was heated. I said, look just tell me some symptoms and he wouldnt budge, but if I flashed green he would have done it. So I left mad, with being on empty the 2nd time this week.

So I went to jiffylube to get my oil changed and asked the manager, the same symptoms and he told me lead foot and i said no, dont have one. He said, fuel injector cleaner, and I said... really. He said, yeah. Have you got them cleaned and I told him no, he told me for 50bucks he could clean them in 15mins and it could well improve my gas. So i told him, i look around for cheaper price first and he said ok, no prob.

Now i remember about 8months back, i bought this stuff called "seafoam" for my sentra, because well she kept bogging and getting bad gas, and man did that stuff open her up, its like she threw up everywhere in my neighborhood . Just wanted to know, has anybody used this stuff? Should i use this on my lancer, its still farely brand new car.

 

I wouldn't many of the products like that clean whatever they have to clean but they
also make the part kind of more vurnelable for another occurence like that.
Just go and get it cleaned by a professional mechanic.

 

$50.00 is not really a lot, and if that thing will f%$#^ your car guess how much you'll have
to spend then ........$$$$$$$$$$$$$$$

 

how many miles have you driven?

You car might need a tune up. Some new plugs and a reset ECU might do you well.

WADAD

 

i noticed you said that you have a SRI and exhaust. this might seem a little weird but when i had the same setup, my car would eat up gas like crazy also (NO heavy foot). then when i installed my header everything seemed to balance out and i had good gas mileage again. i know it sounds weird but thats what happened. maybe something to do with the air to fuel ratio? just a guess.

 

try some stuff by redline called fuel system cleaner it is sold at pep boys for like $5 and it does work amazingly used and my gas milage went like 40 miles

 

I really like the Lucas Fuel Injector cleaner... runs about $3.50 a bottle where I am. Has an upper cyclinder lubricant, and a VERY heavy detergent package. The tank you put it in will get shiat gas milage, but the next tank it'll be like a whole new car.

 

I would be suspicious of air-to-fuel ratio, too. Check that to make sure you are not running too rich. If the car is fairly new and nothing is really wrong, that’s gotta be it.

 

^^^ how do I check that, my fuel/air ratio?

 

These cars should be able to adjust their own fuel trims to get the best A/F ratio. Hell, my '91 Eclipse did that.

If you still have your stock intake, try putting it back in for a couple tanks of gas. See if it makes a difference. If that doesn't work, try it with your stock exhaust. That's the easiest way to see if it's your mods that are $@#&ing up your mileage.

 

Have them check your O2 sensors if they are giving the right inputs to the ECU.

The front O2 may be giving false readings causing the ecu to dump more gas. This will not neccesary trip the "Check Engine light" because it's still reading but not correctly.

Should still be covered under warranty

 

They can only adjust for what the sensors are telling the ECU and to what it was calibrated to. When you change things, such as intake or exhaust, you throw it off from the factory tuned settings. That's why you need reflashes. Also, messing with the MAF and O2 sensors can definitely throw off the ECU. Both of these could well have been altered.

Arithmetic, if the Mitsu guys are useless, try to find a good shop or tuner in the area. Unfortunately, I don't know any in the local area other than the big names you see around the forum. Go figure.

 

Well, so far, he's only said he's got a CAI and axle-back exhaust. None of the sensors have been messed with in that case, and the car should be able to compensate just fine.

I suppose I should have added "to a certain extent" to my previous statement.

Swapping back in his stock intake and exhaust would help narrow down the problem, though.

 

19-20 city seems about right no?...but i have a lead foot so..i dunno....with the piggy im getting around 240 from full tank to when the yellow turns on ....so i dont think that your mileage is that bad...unless mine has also gone to shiet

 

20MPG is retarded low. Even with the test pipe on I was getting 24.7 consistently in mostly commuter traffic.
I put the catalytic back in and not only noticed more low end power (duh) but my MPG went up again. Tuning the eManage for both commuting and racing has helped a lot (both in power and in consumption)
I also notice an increase in MPG after an autoX day..... maybe you DO need a lead foot and a slow shifter hand.... burn out some of the deposits?

My last tank had 311 miles on it before I had to fill it 10.3 gal... and that was in mixed driving (one 50 mile trip to the track, 3 lousy tries at the cones) I'm looking reall good right now at 122 miles and the needle's just below the 1/4 mark (yes, I know it doens't mean anything, really, but it's a good indicator for me that I'm gonna be breaking the 25MPG mark).

Are you getting a CEL? When I was in closed loop (before the O2 sensor CEL eliminator) I used to get crappy mileage too, because the ECU's "Limp mode" makes it dump fuel to protect the internals.....