Maybe O2 sensors, my gas mileage went down a lot before the code kicked on

 

ya see....i havent gotten a code..but its been months of low gas mileage numbers...i wonder if i change out the cats then bam, o2 then start throwing codes...

we use to get 330miles a tank and now were lucky to get 250.

-J
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What mileage numbers are you getting now and what were they before?

 

i know i am going to get yelled at on here for this but, I just took a paddlebit to the guts of mine was getting 16 in town now getting 18

 

Not sure how something in the exhaust system would change mileage too much.

I have a ODBC gauge and my mileage hasn't changed 0.1 mpg since I had one of my two catalytic converters changed a couple weeks ago.

 

A clogged cat will restrict flow and cause what feels like a power loss. There really isn't a loss, just the motor not breathing properly which in turn causes a loss of access to all the motor has to offer. I replaced one of my cats, no change in mileage. The last car I had, on the other hand, the cat was clogged, motor could not breathe, wot caused more fuel to be dumped into the motor without being able to utilize all the available power, thus mileage suffered. Anyone know what these motors are rated without emissions/exhaust systems?

 

^ wow, ya thats interesting.....

ya we have wide open highways in Texas. my modlist is as below in my sig, but we would get 330 no problem and now its way down...

-J

 

Stop and go traffic is murder on SUV mileage.

My cats went out with no codes thrown. Prior to them going, I was averaging 17mpg. Now with a new motor, no cats and long tube headers, the mileage is about the same.

 

Was it the Primaries blowing back into the secondaries?