Horrible Gas Mileage

[Nismo1182]

I filled up my gas tank today, did about 100 miles worth of driving with a few full throttle blasts, but drove normal for the other 99 miles worth.

By night fall im almost at 1/4 of a tank. WTF???!!!!

It doesnt help much that premium gas is expensive.

The car runs rich as hell. I cant even cruise at a set speed without the car starting to sputter. My plugs also come out black.

The car has a Mines tuned ECU. Could this be the main problem?

How can I check that the O2 sensor works?

Im to the point of throwing an AFC on it to try to lean it out some. This is freakin crazy. I cant afford this gas guzzler anymore. Im spending almost 200 bucks a month in gas alone.

Someone please help me. Thanks.:help

[slw240sx]

the mines ECU is prob programed for 550s a bigger turbo, and a z32 maf there for flooding you out. . do me a favor take your ECU out and check and see if you have a socket to change the 28 pin chip in and out easily! if you do ill send you a stock chip for 25$ shipped.

[sammy]

well......I'd be soooooo happy to get 100 miles on a 1/4 tank. right now i get around 75-80 on a 1/4. i guesstimate my mileage to be around 20-21 mpg. At least it beats the 15 mpg when I acquired the car

[Nismo1182]

well......I'd be soooooo happy to get 100 miles on a 1/4 tank. right now i get around 75-80 on a 1/4. i guesstimate my mileage to be around 20-21 mpg. At least it beats the 15 mpg when I acquired the car

Id be happy too.

But unfortunately is the other way around.

I got 100 miles on 3/4 of a tank. I have a 1/4 left now

[Nismo1182]

Oh and what about the AFC. Im sure I can tune it so its not as rich.

[slw240sx]

do you have and AFC on hand? if not it would be cheaper for a stock programed chip. and it would be much easier to work with

[andrave]

I would defintely say its your aftermarket ECU, especially if its one of those "mystery bin" ones. I'm getting my tomei tuned ecu but I know exactly what it is tuned for.Sounds like a quick chip might fix you up.

[Nismo1182]

do you have and AFC on hand? if not it would be cheaper for a stock programed chip. and it would be much easier to work with

My friend has an AFC2 hes isnt using.

Im going to borrow seans stock ecu for like a week or so and see how that works out. If gas mileage improves, im gonna go ahead and trade ecus with him.

If the Mines ecu has a socketed chip in it, ill go ahead and get that stock chip from you. That way ill have the Mines chip for when I do upgrade.