Hey HT,
So I have a 98 hatch cx. On a full tank I'm only getting around 240miles. I get about 20MPG. 20!!! I have all stock motor and exhaust, intake. I do though, have a bad o2 sensor2. I don't think that would cause this severe a drop in mpg though. And has anyone had any success with ebay o2 sensors?

PS: I have a 98 with a 2000 body conversion. I'm missing my right wheel well/splash guard. Which one do I buy, 98-00?

And, I also hooked the car to a computer to get codes, and it gave me the o2 sensor code and also gave me a "trans motor malfunction". I have NO clue what that could be. I have auto tranny. If anyone has any information on that it would be so appreciated!

Thanks a lot guys!,
Evan

 

replace that o2 sensor asap It wont go into closed loop with a bad o2 sensor I was getting 18.8mpg on my del sol but I had more wrong than just an o2 sensor
Like a dark brown air filter..
A stock never replaced fuel filter that poured black stuff when I took it off
A never ever cleaned throttle body

I bought a ebay o2 sensor and it works fine

couldent help you with that trans motor malfunction buisness
Post the actual Cel code like P0xxx

 

Thanks a lot for the tips Lizardslap. My airfilter is super clean and I recently cleaned my throttle body. Only thing I can think is the sensor. I will change it asap.

As far as the code goes, it doesnt come up with a P0xxx code. It just said "trans motor malfuction". Maybe it could be a VSS? Can that go bad and my odometer still work?
Thanks again!

 

That O2 code is killing you...The ecu relies on the upstream O2 sensors to determine if it is running rich or lean.

Denso is a good one to go with (a bit pricey though) or NTK..either brands is OE replacement.

I recommend one made specifically for your car. Cheaper, universal one can definitely work, but they can also cause more problems.

 

Thanks for the responses. If this helps I'll try to describe a problem I have with my transmission. It seems when I apply regular pressure to the gas pedal and am accelerating through 1st gear, right before it shifts to second it, it releases and revs. Like a free rev before it goes to second. Only way I can describe it is like when someone is driving stick and they go to shift to second gear and they press the clutch and rev some before going into second.. I hope that helps if at all anything. I'd really like to get this problem resolved. Thanks again!

 

Go with a Denso O2 sensor. I just tried a Bosch one that was listed for my car (99 LX) and it didn't fit right. The Denso one was a perfect OEM fit. For $35 from Amazon I couldn't be happier. Got the check engine light off and am getting great MPG.