simple

the differencs between the 2 and when they occur
thanks!

badass383

Open loop is when the engine is first started cold. The computer ignores the sensor inputs and richens the fuel mixture to get it to run smoother until it warms up. So computer decision without sensor feedback is open loop. When it warms up, and I don't know at what temperature that occurs, the ECM then starts reading the sensors and making fuel and ignition decisions based on the sensor feedback. Thus the "closed loop" mode. I use a Snap-on anilizer and it tells when it goes out of open loop to closed loop with an led on the front of the anilizer. Sorry about the spelling

turbo_Z

as mentioned above..open loop is when you first start up. in order for your car to reach closed loop is to achieve an opporating temp of 140 and run for 3 min or something...not exactly sure. now the only real difference between the 2 basically is that in open loop you dont get oxygen sensor feedback so the car runs off the computer alone. after it times out and reaches 140, the PCM will start reading the O2s and make any necessary adjustments to maintain the stoic A/F of 14.7:1.

Tires_Smokin

My 02 on the driverside went bad...I still have to drive...any cons to keep driving with bad 02's? I wont get my new ones till next week. Im a daily driver ...will I foul plugs?

Thanks...

gamecockfan04

You'll be fine driving with a bad sensor, but get it fixed and your car should smooth out a idle a bit.