If a O2 sensoris going bad...Could it cause me to get horrible gas mileage, and a kinda unconsistent idle(moves up and down a little when cluth is engaged, no tach in my car but it doesnt rev high prolly from like 1k to 500k). Typically i get mid to high 30's in my 92 CX, but lately i been getting 20mpg if that.

I think it is the O2 sensor because every now and then my CEL will come on but once i shut off my car and start again, its gone.

Oh, Yeah my car runs real rich too, i got black all over my bumper...no blue smoke(aka burnt oil).

My mods include a 16 valve head(nonvtec), full exhaust and z6 throttle body.

One more question, when i switched from the 8vavler to 16, should i have switched the timing belt too?...because my car will sputter sometimes like the timing is off a little.


Please Help

 

its all tied intogether.

your 02 sensor monitors output from your engine.

apparently your check engine light is coming since your engine is running rediculously rich.

your engine computer tries to compensate for your engine's exhaust readings causing your gas mileage to possibly suffer.

my advice to you is to get the sensor replaced. they ain't cheap by the way.

 

Yes, a bad O2 can cause your gas mileage to suffer as well as running too rich. Not sure about the eratic idlebut according to the first 2 symtoms your O2 definitely needs to be replaced. Try to avoid universal sensors, I've heard they are notthat good. Go for denso or NGK, there are a few others too just can't think of them right off hand. More than likely it's your pre-cat sensor, but it wouldn't hurt to have your cat sensor checked as well.

Edit: Byers beat me to it.

 

Thanks for the quick reponse. I figured it would be one cause of my problems. Any idea about my timing belt question?

 

i may be wrong drbyers but arent o2 sensors like $50 and easy to put inurself, just bolting of the header?

 

wait a minute exactly how many o2 sensors are their lol???

 

well if youve got a 96 or newer car, you have an OBD2 ECU, which means 2 o2 sensor. 95 or before = OBD1, which means 1 o2 sensor.

OBD2 = on board diagnostics, 2 o2 sensors

 

yooo flippp thanks, now i understand wut the obd's mean, so obd0 meands no o2 sensor correct???

 

o2 sensors arent cheap if you get them through a dealer or parts provider...but yes they are easy to install

 

i dont think that's correct.
my o2 sensor was 22 dollars