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Discussion Starter · #1 ·
I'm getting around 12-13mpg driving a mix of highway and city driving. I live in NYC, there have been times where i was stuck in traffic for about 20-30 minutes.
The car is a 94 Turbo, 6spd. Spark plugs were done at 90k. Car has 94k on it. The O2 sensor was never changed, there were no codes that show the O2 sensor was malfunctioning, but im not sure if i should just get a new one anyway.

The car is basically stock but i think the car is running rich
Heres what i have:
Apexi GT-Spec exhaust
RMM downpipe (with removable flanged high flow catalytic converter)
K&N drop in filter
HKS aluminum intercooler pipe upgrade
Greddy BCC
NGK 6097 plugs
Hallman manual boost controller (it is tuned down to run at stock boost)

Are any of these modifications causing bad gas mileage? i did a search and it seems like it could be the O2 sensor but before i go and purchase a new one im trying to definitely pinpoint the problem. Could it be the fuel injectors?. Car has stock fuel injectors and i know for a fact that they have not been changed.
 

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After purchasing a new o2 sensor the car runs leaner while cruising and just overall much better. But BPU is also just a gas hog, especially up top. If you can find a way to read your a/f's see what you are cruising at and what your idle is at.
 
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AtlSupra said:
Try change the O2 sensor, fuel filter and clean the injectors.
how you clean the injectors? just buy those injector cleaning bottles that you add to your tank? or remove them?
 
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I bet its the O2 sensor. After I got my 02, mileage improved tremendously. From like
less than 10mpg in the city to 14-15 at least
 

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1993.5 White Turbo Supra
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I have a 93.5 MKIV auto tt.. 94k miles, bpu, get about 14-16 mpg city.. dont know the highway cuz i haven't done long hwy drives since bpu.. prob just need the cleaning.. no need to buy spend more $$ on buying new ones if the old ones are fine..
 

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Supra Owner Since 1996
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2,715 Posts
From experience.
BPU 15/20
APU 13/18

And yes you should replace your O2 sensor. I've had them go out without throwing a code. $112 from Curt.
 

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I definitely agree with the O2 sensor replacement. That can definitely lead to abnormal gas consumption.

But.....

What about turbo timers? I hope you all have turbo timers. Think about it, if the car idles ~4 minutes each time you run it, that will definitely eat up some gas, even though the car is just idling.

Just something to think about....
 

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heres an idea... how about getting some sort of fuel management like the map ecu. people sell them a lil bit cheaper here and there. i bet you could work out the fuel at cruising.

also, ive heard apu getting up to 28mpg with an aem tuned well and off boost on 900cc+ injectors.
 

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I get around 12-13 in city and just recently did 212miles on half a tank of highway dirving. So I think that is about 22miles to a gallon. This is with a big single and 1000cc injectors. The 02 sensor should help out as it is probably at the end of its life.

Lawrence
 
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