2000

[manev]

Have code for o2 lean and misfires, replaced plugs still runs ruff, would o2 sensor cause engine to misfire ?

[fishexpo101]

Need more info - year and mileage? Any mods to the car? Did this just start recently or has the car been running rough for some time? Maintenance history of the car?

[buci]

It's not likely an O2 will cause the misfire. Do a complete tune up on the car before starting to change things.

[manev]

Bought 2000 Corolla with 129,000 miles, failed inspection due to Random misfire and lean o2 bank one. Put in new plugs and 2 new coil over plugs $90 each and pvc valve. Car still runs rough especially when cold. Car will pause when pressing hard on the gas then slowly pick up.

[rgurleyjr]

Go to Autozone or Advance and get your codes checked.

[phantazn]

bad readings from a dying o2 sensor may tell your ecu its running lean when its not, and flood the cylinders with way too much fuel, thereby causing misfires. just had this same problem on an 01 rx300.

[iskate631]

i had a slightly similar problem a little while back, the rear o2 sensor went and caused the idle to be way out of whack, and another time my wires went the gas pedal choked up a bit when i stepped on it at a low rpm

[manev]

Replaced front 02 sensor, new plugs and PVC valve, cleared codes for misfire and lean bank 1. Still runs ruff, stalls when hitting the gas hard. Light came back in one day with the same codes for misfire and lean. Now what ?

[teppista881]

Try cleaning your MAF sensor. Unplug battery and sensor, unscrew sensor, and blast it with MAF sensor cleaner. Let dry, reinstall. I do this at least once a year to keep the lean code (p0171) away.

You might also check for vacuum leaks around the intake.