Alright, so I had a hunch that my 95 ST was a little thirsty as of late, and to test it I put exactly three gallons in and reset the trip. Turns out I'm getting between 10-15 mpg
I know that I need to fix a crack in an exhaust pipe (driving on dirt roads riddled with large rocks through Colorado forest with the lowest sitting car ever created by man was a case of poor judgment in hindsight), but other than that I'm a bit confused. During the summer I could smell gasoline when driving, so I suspected a leaking fuel pump perhaps, though the smell disappeared with the coming of winter. Even then, I was getting about 35 mpg highway in the summer.

The only other thing I can think of is that I put in a new air intake, and followed the guide on resetting the air/fuel mixture. Could be that I did it wrong, but I have no idea how it would result in this poor of performance, especially as I don't notice a change at all in the car's driving. I've checked for leaks in the fuel line, but it's solid.

Anyone have some advice?

I'm new here by the way, name's Nick. This site seems incredibly helpful already, and I've been looking for a resource like this for a while. Celica's forever.

Welcome to the forum! All you can try is a tune up! is it misfiring at all?

Tune up is spark plugs, leads, distributor cap, rotor and a fuel filter couldn't hurt.

The engine is running fine, all cylinders firing, no knock. The spark plugs are almost brand new, but I guess I could check the other aspects. For some reason those don't seem significant enough to cause this bad a decrease in fuel efficiency.
This is a recent problem. Could a faulty reset of the ECU be causing it? (The only thing I touched were the fuses...)

change your primary 02 sensor.

switch to unleaded foot, thats what most people do... after you try switching the O2 sensr.

I get smoked by raisins in Buicks at stoplights, I can assure you it's not my driving. O2 sensor sounds like a promising fix though. Thanks for that advice. However, the engine light has never come on, is that something OBD would report?

This post has been edited by senick: Mar 29, 2011 - 9:29 PM

raisins... ROTFLMAO!!




but seriously, when the O2 goes is starting to go bad, it wont always trigger the check engine light, it may not have gotten that bad yet.

Alright, O2 sensor it is. And I'll fix up the exhaust. Only question now is: Denso or Bosch?

Is it a question of using some CRC or WD40 to get some carbon off the tip of the sensor or is some **** burnt out?

Haven't taken the sensor out of the socket, but I've 161K on the motor, and I'm almost positive that's the original sensor. Even if it just needs cleaned, it's well past the point of replacement anyway, and $40 isn't sacrificing too much (especially considering I'll hopefully make that up in a few weeks in fuel savings).

id go denso

Replace the sensor AND fix the crack in your exhaust. The crack might also be throwing off the readings of the senor.

>

When was the last time you checked your oil? Mine burns oil and once it gets to a certain point my gas mileage drops significantly.

Well, I checked the oil recently, and it looked fine. Only a few days until my next scheduled change anyway, but I'll check again.
Good advice on fixing the exhaust crack as well. I was planning on doing that, but makes sense that it could be throwing off sensor readings.
Hhhhh...time to get out the jackstands...

yeah just do your tune up, i just bought a gt, put ngk spark plugs, spark plug wires, then new air filter, changed oil and put new fuel filter and its gettting about 30 mpg.

Pop your hood while the engine is running and sniff around -- an O-ring on an injector could have gone, which would lead you to be leaking gasoline.

Yeah, I've already done that. No trace of gasoline, thankfully!

Do you have a vacuum leak? When I did my car was guzzling gas.

i was getting about 20 mpg for awhile. replaced my O2 sensor with a bosch universal (cut off oem plug, crimp, solder, and heat shrink on new sensor) and its jumped back up to ~30