A few years ago someone on here told me to change either the TPI, or the PCV, or the oxygen sensor every year to improve the gas milage. At the time whichever it was had been working fine. (no codes) When I replaced it I saw immediat increase of 3 mpg. Does any one know which one it would have been?? I can't remember.

This getting old ain't all it's cracked up to be.

 

The oxygen sensor. I usually dont replace mine until it goes bad though. You can get a higher flow airfiter and that will help aswell. I use KnN. Fram is the worst.

 

Already have a K&N filter.

Thanks

 

The upstream o2 sensor is the one that controls the fuel mixture... When mine went out my MPG dropped to 8.

 

Ok, so I'd like to change it myself if I can. How do I find it??

It's a 2000 4.7ltr.

Thanks

 

They're on the tail pipe. Upstream is the one closer to the engine. Downstream is almost at the end of the tailpipe. They look like sparkplugs with wire connectors on 'em. Just unplug the wires and unscrew it. If you don't have a check engine code you shouldn't need to replace it. If you do, check and make sure the wires didn't just come unhooked.

 

I'm not trying to be a wise guy or anything, but, did you read this before you replied?

 

Ya. I was just telling you how to find it.

 

oxygen sensors can most certainly go bad without throwing a CEL code, however replacing them yearly is way overkill. the PCV is a regular maintance part that should be replaced, however will not throw a code if it goes out either.

 

Shrps is right. Doing it yearly is excessive unless you keep getting lemons that go out right away. I replaced my OEM one last year, they will last for quite a while. Now did you lose your 3mpgs again or are you just trying to improve it more?