I have a frustrating 2001 Toyota Corolla. The check engine light is on and the computer indicates an O2 sensor is bad (the one ahead of the catalytic converter). It’s pretty clear the engine is running lean, is this typical for a bad O2 sensor? Let me describe a bit of the abnormalities regarding the engine running.
When I start the engine, it starts right up without a problem, but the idle is up around 2k rmp. The idle gradually slows down to about 1200 rpm until the car is warm. Once the engine is at normal operating temperature, 50% of the time the idle will be so low that the car wants to die. The rest of the time it idles around 900rpm.
Acceleration is also odd. I get massive hesitation when trying to accelerate 95% of the time. The other 5% of the time the car behaves perfectly. Also, if I run the air-conditioning the car runs pretty well, and hesitation is difficult to notice.
Often times if I stop the car for 10 minutes or so, the poor engine behavior ceases. And the car runs like it’s supposed to…
I have replaced the spark plugs, mass air flow sensor (thinking that was the problem). The plugs were change at a shop and the mechanic said the electrodes had nearly disappeared. I’m planning to change the O2 sensor this weekend…
Any thoughts and or help would be greatly appreciated!
Also this thred discusses my problem to a T. But no solution was suggested.http://community.cartalk.com/discussion/2279294/corolla-check-engine-light-stalling