O2 question
Melting Slicks
Joined: Nov 2013
Posts: 2,049
Likes: 316
From: USA
The front O2 sensors provide feedback into the ECU during idle, cruise (most conditions) to maintain 14.7 AFR. This is called closed loop. At wide open throttle the ECU goes into open loop and then your AFR goes to something richer than 14.7 and the factory narrowband O2 sensors are worthless so they don't do anything-- regardless if you're on stock or custom tune.
Hope that answers your question.
Hope that answers your question.
Thread Starter
Instructor
Joined: May 2013
Posts: 184
Likes: 22
The front O2 sensors provide feedback into the ECU during idle, cruise (most conditions) to maintain 14.7 AFR. This is called closed loop. At wide open throttle the ECU goes into open loop and then your AFR goes to something richer than 14.7 and the factory narrowband O2 sensors are worthless so they don't do anything-- regardless if you're on stock or custom tune.
Hope that answers your question.
Hope that answers your question.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
I agree The rear 02's only report the condition of your cats Typically with headers you will get false codes and reporting from the rears--so most tuners simply turn them OFF
The front 02's are completely different On a stock OL/CL tune the front 02's are the measuring device that will make adjustments to your P/T fuel to correct the AFR to the stoich 14.68 VIA your fuel trims----This OL/CL stock system works well up to around 450 RWHP----beyond that tuners will alter the stock OL/CL tune to run either an OL tune or a speed density tune--depending on the mods you used--An OL tune or a Speed density tune will most likey NOT use the front 02's--so they are then turned OFF--
The front 02's are completely different On a stock OL/CL tune the front 02's are the measuring device that will make adjustments to your P/T fuel to correct the AFR to the stoich 14.68 VIA your fuel trims----This OL/CL stock system works well up to around 450 RWHP----beyond that tuners will alter the stock OL/CL tune to run either an OL tune or a speed density tune--depending on the mods you used--An OL tune or a Speed density tune will most likey NOT use the front 02's--so they are then turned OFF--
