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TERRIBLE gas mileage....

XbajajeepX

XbajajeepX

NAXJA Forum User
Location
So. Lake Tahoe
Ok so I ave been getting VERY bad gas mileage for the last 2 weeks.. I am getting around 7 MPG, the jeep is stock with 30's... The check engine light has been on for around the same time, also.... I figured it was an O2 sensor.. My fiance works at a jeep dealership so I took the jeep in today and the guy ran the system and it said cylinder 6 misfire. He took care of that by updating the computer... I have not had enough time to drive it around to see if the mileage is any better, but would a misfire cause that bad of mileage?? Thanks,

Mike
 
Anyone??
 
No, he hooked it up to a computer and said that the computer needed to be updated or something... I dunno but it defintetely runs smoother now..
 
The update if it is a 96 is for the cat. It does something to the engine management system to detect if the cat is bad or not. A misfire you should feel. When was your last tune-up? Oil change? and type of oil. Year? we need more info. Did you pay attention to your temp?
 
its an 01... I changed ALL the fluids, spark plugs, filters, belts, everything about 3000 miles ago..... I used Royal Purple oil... The temp is fine... and it has 110000 on it.

All I know is he hooked the scanner up to the jeep, it said cylinder 6 misfire... He then took the scanner over to a computer and uploaded something to his scanner, then, hooked it back up to the jeep for a good 10 minutes till it was done doing whatever he was doing... It definetely runs smoother now, though... I drove it a little tonight and it seems the MPG is back to where it should be..
 
Last edited:
Well the gass mileage is back to normal.... So whatever he did with the computer worked..
 
There are two O2 sensors on mine. I had great mileage (22+mpg) and went down to 12 ish when the ck eng lamp came on. Downstream O2. Mileage is back now A-OK
 
Ok so my mileage took a turn for the worse... I will only get like 200 miles to a tank at best...

The idle has been acting up a little, now... It will idle just a tad high throughout the day. Its not constant but just every now and then..

Any ideas??
 
I would change out the #6 sparkplug. I did a plug change on the wife's Explorer last week, had a miss, and found a plug that was bad right out of the box. Just because they're new dosen't mean they're good.....

I'd also clean the throttle body and IAC. That should cure the intermittant poor idle.
 
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