A/F ratio plots - normal?
10-24-2004, 06:10 PM
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A/F ratio plots - normal?
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.
Anybody else did these plots? I have the A/T RX-8, hence my RPM values.
10-30-2004, 07:22 AM
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Originally Posted by bxb40
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.
Anybody else did these plots? I have the A/T RX-8, hence my RPM values.
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?
10-30-2004, 12:24 PM
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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).
It clearly shows the trend of massive overfuelling to maintain an acceptable cat temperature (approx 960°C).
11-10-2004, 01:28 PM
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Originally Posted by JasonHamilton
your car will do that in closed loop.
When logging data, delete anything under 5000 rpm to prevent it from poluting your information.
When logging data, delete anything under 5000 rpm to prevent it from poluting your information.
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?
Under increased engine load the optimum air/fuel ratio is richer than the stoichiometric air/fuel ratio in order to give maximum engine output and prevent engine damage.
Last edited by davefzr; 11-10-2004 at 01:31 PM.
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