Burning gas like crazy!

[BonesOfSteel]

Hi..
I have had this 95 BMW for about 3 weeks now and I seem to be getting very little mileage. It had a messed up thermostat when I bought the car but I changed it aswell as my spark plugs/air filer/fuel filer. It has a 45L tank and I did 325km with lots of highway and the next week I drove 50/50 and did 310km. This is my 3rd fill up and I at the halways mark and I did 207km. I am going to change my o2 but I don't think it will make a huge difference since I believe I should be getting like 600km a tank which works out to like 7.0L - 8.0L/100KM
I use 91 Ocatane gas, and I am not driving it hard at all. Thanks for all your help!

[Tyler]

Have you changed your fuel filter? Also plugs and wires would be good to change. I don't know km's but i normally get 31mpg city and 36 highway,i drive all highway so i get about 400-415 miles to the tank.

[SparksTi]

check your exhaust, especially the cat. a restricted cat or exhaust system will kill your gas mileage. I went from 20 mpg to 35 mpg after finally finding out that my cat was all jacked up.

[Tyler]

If it was the cat then he /she would notice a funny sound and the carwould be very slow. When my cat was gone i couldn't even ull onto the highway,thats how slow it was.

[Mendi3]

Check your O2 sensor. It may be going bad. The good thing is that 95's have only one O2 sensor.

[BonesOfSteel]

I am guessing it is my o2 but I can't see it decreasing my mileage that much? They say I should be getting around 500 - 600km per tank city/hwy. Would an o2 decrease the mileage that much?? Thanks

[J!m]

It could also be a clogged air filter...

[Mendi3]

Originally Posted by BonesOfSteel

I am guessing it is my o2 but I can't see it decreasing my mileage that much? They say I should be getting around 500 - 600km per tank city/hwy. Would an o2 decrease the mileage that much?? Thanks

It's hard to tell. I know that if the O2 sensor is going bad, the mixture of fuel could be increased significantly since is not getting the right mix. If you have access to a scanner it will tell you if the O2 is bad.

[ClubSport]

My vote is for the oxygen sensor. Mine went from 30mpg to 20 overnight when it went bad, and replacing it brought it right back to 30.

[BonesOfSteel]

Well I spoke to my mechanic today, he says if it was my cat I would know right away because the car would be really slow and only get worse. The told me he checked the o2 last time and it was reading right. Even if it was the o2 it would not cause a decrease of 300km to the tank. I am doing 14.7L/100KM thats like driving a corvette. He said it could be something with my intake. I checked the filter and it is almost brand new! He said before the filter. I just don't know what would cause such a huge decrease in km!

[dodj]

I get 500-550 km per tank using premium fuel
and i get 600+ when i use regular 91

I have tested this numerous times over similair driving conditions!
does premium burn more or something?? i thuoght premium meant to give you better consumption

[thefys]

Hey,

I also have a ti that burns too much gas (I think) . Speed is not a problems o I doubt it's the catalytic. I get 220-250 miles/tank in the city and maybe 310MPG on the highway. Filling with 91.
Is that normal ?
Did you figure out what was causing your low MPG ?


Yanni

[bullmand]

Bones,
How many miles are on the car? I ask because the recommended replacement interval for the 02 sensor is 100,000 miles(160,000 km). I was just reading in the Bentley manual the other day that just because the 02 sensor shows the correct voltage when it's tested doesn't neccessarily mean it's OK. Apparently as they get older they slow down(like people!) and the only way to check it is to pull it off the car and use an oscilloscope. So, if your mileage is that high, you may want to still consider replacing the sensor. Since you didn't mention it I assume you don't have any warning lights lit. This probably won't help but have you tried any injector cleaner or fuel system treatment?
Good luck and let us know what you find out.

[Etienne]

If you figure out the problem I would be interested to know.

I have replaced my 02 sensors (though the fault code reader is still reading an 02 sensor fault... checked the 02 sensors and they appear to be working fine).

My gas mileage is sucking horribly though, and I can't figure it out. Fuel filter is next on my list when I get a chance to crawl under the car again, but the CEL worries me a bit because it won't go off... :/.

Anyway, if you find a solution, post it up

Cheers.
Steven

[davep-uk]

i'm coming up to 100k and i'll change the o2 sensor when i put in for service in a month or so, but what do they cost? i can feel that coupled with the full service, suspension work and brake work its gonna be an expensive May.