My 95 GS-R using a lot of gas!!! need help
 

what shall i do???
literally the whole tanks gives me around 200 miles

iv done the whole tune up as well
which includes:
NGK plugs and wires
Injen Short Ram
Greddy EVO2 Catback
Fuel filter has been changes
Valve timing was adjusted

dont know if this matters or not but the guy who sold me, told me that the ECU was stolen some time back from this car so he had it replaced by some other ECU from a legend, but according to my knowledge legend ECU's are for a V6 engine so i didnt buy what he was saying. but the car ran fine and no lights were on, my mechanic said its ok as well...my question here is that is it possible that the way my GS-R consumes gas might be because of the different ECU
if so what shall i do? how do i check what kind of ECU i have?

That ecu is probably making it run pig rich if it is in fact a legend ecu. I would pull it out and check to see what it is and replace if necessary. Also, have you replaced the cap and rotor?

ohh yeah the cap and rotor was also replaced in the tune up (forgot to add that)
yeah i wanted to check the ECU out but how would i know if its the right one?

just found a link which tells me which ECU i have and which one is required...kinda helped my self out
but is there any thing else that effects the mileage of the car?

Do you drive it like a maniac? That has a huge effect on mileage. It calculates to around 19-20 mpg assuming you are putting a little over 10 gallons in which is a little less than what I am getting.

On a side note, I calculated my MPG just driving around in boost and it calculates to around 6.6 MPG, so you can really see how a lead foot can affect your mileage.

naa man aint doing the whole maniac driving.....just in city driving mostly...
home...work....home...college...
thats about it
taking it to Ohio tomorow il see how that goes....

NO IDEA what you are expecting with city driving. city driving murders gas mileage. i only get to 300 miles on a full tank if im doing straight highway driving. and thats not very often i do that. stop and go, sitting in traffic, accelerating, decelerating ALL affect your gas mileage. so, your MPG seems just fine, totally normal to me. I wouldnt worry about it, but if you are SO worried about it, you might want to do simple tune-ups, such as oil change, induction service, new spark plugs, wires, cap & rotor, all these things will help you with gas mileage. but city driving, expect AT MOST 230 miles on a tank.

The only thing I see missing from your tune-up regimen is replacment of the oxygen sensor. The OBD-I ECUs allowed a wide tolerance in O^2 sensor input before tripping a Check Engine Light (CEL). So just because your CEL isn't on, it doesn't necessarily mean the O^2 sensor is operating at peak efficiency.

For the record, I only got about 22-26 mpg in stop-n-go driving, so your numbers aren't that far off. If you don't have records of the oxygen sensor being replaced within the last 3 years or so, I'd spend the $30 and 20 minutes required to replace it.

Also, save your gas reciepts and keep track of your mileage via the trip meter. Our gas gauges are not accurate enough to be very helpful in tracking mpg fluctuations..

200 miles isn't bad for city driving i get about 300-350 miles to my tank and i drive 40 minutes of highway everyday

JRSCfed LS here only getting 16-19mpg, mixed