4agze Running Rich

[TruenoGTV]

my corolla has been running lean recently without the o2 sensor (dyno figures showed 177bhp and 178ft/lbs). YesterdayI fitted a genuine toyota o2 sensor and reseted the engine management light, but after about 5 minutes of driving the code 21 blinks, and it seems to run more different, I get the odd puff off smoke.

I have re-checked all the wires and it seems fine. Also I get lots of pops and bangs out of the exhaust, it seems to me as it is running too rich.

Need help

[Unity Jon]

if you fitted a decent air filter the car would probably have run slightly lean because its able to suck in more air with less effort than before, if you had it tuned they should have turned the mixture screw in slightly on the throttle body to richen it back up, IF they had the required levels to hand, its easy to over do this. By fitting a new 'clean' o2 sensor your ECU has probably increased the mixture some more, maybe too much, lean the mixture back with the screw in the throttle body, beware, its very, very sensitive.