sajohnson05

I know there has been tons of Bad MPG threads but i wanted to let you know what is going on with mine.

I have a 1998 Jeep XJ with 4.5" lift and 31" tires, stock gears at the moment. I have been getting between 150&160 miles to a tank and put in around 16-16.5 gallons of gas. I am not having any issues except this. The idle is good, when start will idle at 1000 RPMs and drop to around 500 RPMS while idle. I do have a slow crank sometimes, I feel that my fuel pump is about ready to fail but nothing else is going on.

Any ideas would be great.

Fred/N0AZZ

Check for any codes and do a full tune-up also check differential fluid for starters.

JPXJMOAB

Agreed on the tune up. With that poor of gas mileage my guess is a vacuum leak.

BlueRidgeMark

Right there is the first problem you need to fix.

"Mile per tank" means nothing.


Well, that's not precisely true. It usually means you think you know what your mileage is, but you don't.

It never means you know what your mileage is.


Your gas gauge is not anywhere near accurate enough to judge your fuel usage.

Accurate odometer readings (adjusted for tire size if needed) divided by fuel pumped, as measured by the gas pump meter, is the ONLY correct way of determining your fuel usage.

Any method that involves your gas gauge is worse than worthless.



Work that out first and see if you have a problem. Then start checking the basics. Vacuum leaks, O2 sensor.

sajohnson05

I have just recently got BlueDriver and i have attached a live feed with my 02 sensors and was wondering if anyone could tell if my 02 sensor were bad? Any information would be great.

BlueRidgeMark

All you need to know is right here.

sajohnson05

This was my thread. Just was updating it.

BlueRidgeMark

My apologies.

I wish there were a good place to get info on what typical readings are. It's one thing to have those nice numbers, but it's another thing to know what they mean!

I think CCKen knows more about them than anyone else. Maybe he'll chime in here.


One thing I notice is that you are running a bit cool. Was the engine fully warmed up?