My O 2 volt under 3000 RPM goes from .87 to .01. It changes when the APR Air Pump Relay and the PAC Port Air Control switch back and forth. Under 3000 RPM my car seams to stumble, kind of like a surge. I checked the ground on the O2 sensor it looks fine. Is this normal? Thanks for any advice.

 

it should continue to go from the lean side (.40 or lower) to the rich side (.60 or higher) as its in closed loop mode. In closed loop its using the O2 sensor to find the best lean run condition for good gas mileage. It'll cycle up and down like that until you punch it and go WOT. If it stays at .01 while you are accelerating, then something is wrong. Is the sensor new?

Tim

 

I am unsure what closed loop means. If I hold the throttle at 2500 RPM APR Air Pump Relay and the PAC Port Air Control switch back and forth when this happens every few seconds and when it switches it goes for .87 to .01. As i am driving a low RPM under 3000 RPM my car want to learch foward why I am hold the throttle in a fixed position. Yes I put a new O2 sensor on when i put the Down Pipe on a month ago. Car runs good at Full throttle and idles fine runs very smooth.

 

Closed loop mean its trying its best to find the optimal fuel mixture to run as lean as possible, better gas mileage, without popping the motor. It goes back and forth, from low .01 to high .9's as it gets info from the O2 and adjusts for it so it continues up and down, but it normally doesn't cause a surging effect. How noticable is the lerching? head bucking or just enough for you to notice it and not a passenger?

Tim

 

Tim,
Yes, it it not much of a surge noticable by me the driver only. It is not noticable unless you are driving at a slow speed at low RPM's less than 3000. It only happens when you first drive the car for the day for the first 10 to 15 miles. After the car is warmed 10 to 15 minutes of drive time I can not tell it at all. I almost was ready to replace the O2 sensor tomorrow. Thanks for any additional advise.

Dale