Need some opinions or personal experiences.

[Win94]

Fellas, i have a 2000 Jeep TJ SE with 125,000kms running 31" procomp all terrains.  It of course has the stock gearing , 4 cyl and 60 liter tank.  I have been commuting on the highway to Fort McMurray from Edson  and have noticed gas mileage getting worse.

On a full tank i am lucky to get a range of 400 kms (248 miles)  If i had a bad O2 sensor would this cause a reduction in mileage??  Also if i had a bad O2 sensor, wouldn't it throw an engine code or throw the check engine light on??

[bae146]

AAHHHHH the joy of computerized autos.  Your computer in you jeep will only set up a code or fault of the information from that sensor is outside a particular value.  So you o2 sensor could be providing inaccurate info but not to far off, so you get no code and poor mileage.  So start with the basics, when was the last time you changed your plugs, checked your air filter etc...?  When you check your air filter check you mass airflow sensor and see if it is dirty.  Check your tire pressure.  Your O2 sensor has a lot to do with finetuning your air fuel mixture but you temperateuse sensor has even more to do with how your computer schedules fuel.  If you computer doesnt see a warm enginge it will always think you jeep is still in warmup mode and never schedule fuel correctly.   Sorry I have not given you any magic answers but with these new cars everything is so interrelated it is hard to guess what your problem may be,


Start wit the basics and go from there.  Best of luck!!!