Low MPG help! 91 GT

[Psypher]

Hey everyone, I'm looking for some help with my 91 GT. First off, I bought this car about 4 months ago for really really cheap (It had a few issues, exhaust, paint, etc) but nothing huge. Anyway, i've noticed that i've been having terrible MPG since I bought it.. doing some research on the issue has always pointed towards changing the o2 sensor. So i'm here to ask you where it is located! I've been told this car only needs one of them, but I'm not 100% sure where it is. I thought I found it in the engine compartment but i'm not sure .. please help!



Is it that rod in the center(ish) of the image?

Thanks!

[Cali90sGTS]

Bad O2 sensors or clogged or malfunctioning EGR system can cause bad MPG..
The rod sticking out is a O2 sensor if your car is in California then you should have two O2 sensors.. You should start checking the cheaper parts before you go crazy with the O2..

[Psypher]

What cheaper parts would you recommend looking at? The o2 sensor seems fairly cheap to replace (as far as I know it's never been replaced, and i'm sitting at 157,000 miles). My local autozone has it for 30-40$. I don't live in Cali so I only need one.

[mrlieu]

Yes that one in the head shield is the o2, change that out! I would also replace the fuel filter, that has some to do with mileage too.

[blaze]

i replaced my o2 sensor thinking i would get better mileage but nope its still the same, i should of did the fuel filter first... thats next on my to do list once it gets warmer, im missing an extra 100kms per tank

[1990CelicaGTS]

I replaced my o2 from autozone. Run better after my old one got toast from using them fuel injector cleaner... I should just bought the OEM o2 from toyota for only 129$... Now that I having a code 25. My 2nd o2, after the cat. convertor is bad. I could not take that out. Seem like it got melted in with the exaust flang... Thinking of cutting it off and try to drill it out... They said that the 2nd o2 is nothing but to check your cat. convertor but when I have that code 25, the car would heat up pretty high, and start to smell. I always have to reset it...

[Huaraches]

Mine is currently going through bad mpg so im thinking egr ?

[BottleCapBandit]

Originally Posted by Huaraches

Mine is currently going through bad mpg so im thinking egr ?

Yup. Fuel filter will also show hard starting and irractic acceleration and idle. Same with ignition components. You will get about 15-20 mpg with a stuck egr. Stuck egr will also cause ping.

A full fuel filter will cause about 3-5 mpg drop, same for ignition system. Now dont get me wrong if your car hasnt been maintained then it very well could be multiple reasons for bad mpg. Alot of factors play into mpg. How good are your tires. You can pick up 3-5 mpg from bad to good tires. Has you cat been changed? It would need to be changed if not. Are you using the correct oil for the ambient temp?

You could point and shoot at our cars on what needs to be replaced. Not knowing the car and the background of the engine.

With all that being said. If you notice a pretty big drop in mpg first thing to check is egr. EGR (exhaust gas Regeneration/Recirculation) takes unburnt gas in the exhaust and routes it to the intake for another combustion cycle. This is for emissions but will also save gas. It dirtys the motor up but gives you a healthy boost in mpg.

[Huaraches]

what about cleaning the canister? my fuel filter was changed less than a year ago ive driven my car 6,000 miles approx..... my car has 127 k approx so my cat should be fine yes? idk about the O2 sensor they look grayish i only took out the first one. tires are semi new only 6k on them (Micheline tires) stock size 185/65 r14 (32 psi F 28psi R) i blew air through the EGR VACUUM MODULATOR and cleaned the lil filter in it. air flew through it so it should be fine? but i havent check egr valve