I replaced my front O2 sensors that had 113k on them yesterday with a pair that had 20k on them. Man, I wish I hadn't done that. After switching them I took my car for a test drive. It ran great, at first, but after 20 mins. my car would barely move. I couldn't even get it over 30 mph. It was starting to backfire and stumble like crazy and the exhaust smelt extremely rich. Finally got it home and put my old O2 sensors back in. It runs a little better. It can actually go over 30 mph, but it still has a bad stumble, and it's missing pretty bad too. Any ideas what all I could have screwed up? I'm guessing sparkplugs, but any other info. would be great.

 

Did you burn a wire in the process of putting the new O2's in? Check the O2 wires all the way back to the PCM.

Also, disconnect the PCM fuse for a little while to reset it after the O2's. That way it can start fresh for when it adjusts the fuel trims.

Dan

 

All the wires are fine for the O2 sensors. I had the battery disconnected while I put the old O2s back in so the PCM was reset.

 

ttt

 

the "new" pair that u put in with 20k on them could have been faulty.