I pulled the A/F numbers out of the ECU and plotted them in Excel. Seems that my engine likes to sit a lot at 14.7 and 15.0 (the first statistical freq. plot). The second plot is RPM versus A/F.
Anybody else did these plots? I have the A/T RX-8, hence my RPM values.

 

your car will do that in closed loop.

When logging data, delete anything under 5000 rpm to prevent it from poluting your information.

 

Or capture the fuel system status and remove anything that is logged when the status is "closed" (i.e. closed loop)

 

Interesting, and normal.

Can't you collect and plot WOT curves instead of random running involving close loop?

What 'tool' did you use? Or did you connect directly to the lambda sensor?

 

I used the CANScan tool, then got the file in Excel. I'll try other values combo, see which ones looks best. Thanks everybody for your suggestions!

 

These are curves I measured using the (still in development) Hymee CAN OBD tool. It's WOT data taken during an accel from 4000 to 7500 rpm (Std Power, sorry!).

It clearly shows the trend of massive overfuelling to maintain an acceptable cat temperature (approx 960°C).

 

Does the closed loop cycle end at 5,000 rpm? Can this be changed with tuning software and or would you ever want to?

Why not just keep the closed loop on all the time since it automatically trys to meet the optimum AFR based on the sensors?

Is it because of this?