Commanded EQ Showing 1.13 Lambda in Scanner (1.13 = PE of 1.13)

[Dave_In_VA]

2005 Corvette, E40 ECM.

I'm logging data in lambda.

The tune has Stoich AFR set to 14.7:1. PE is set at 1.13, when combined gives a 13:1 AFR when PE is enabled. PE is set to engage at 3600, its been engaging about 3200.


In scanner, the "Equivalence Ration Commanded (SAE)" below 3290 RPM shows a lambda of 1.000. Then PE gets triggered and EQ Ratio Commanded shows a lambda of 1.13.

Picture of Commanded EQ = 1.000 2022-06-13.jpg

Picture of Commanded EQ = 1.130 2022-06-13 (1).jpg

A lambda of 1.130 equals a AFR of 16.61. My wideband gauge is nowhere near that lean.

I believe that scanner is improperly reading the lambda. Also, according to scanner, the car is super-rich at full throttle.

Ideas anybody?

[pannetron]

From the Editor description for EQ Ratio: "[ECM] 12400 - Power Enrich EQ Ratio: This is the main table that is used to tune WOT fuel. The values in this table are Fuel/Air multipliers (or Equivalence Ratio) ie. values greater than 1 are richer, values less than one are leaner. The values relate directly to the Stoich AFR and the resulting commanded AFR is Stoich divided by this PE multiplier. Eg. if the multiplier is 1.1 then the commanded AFR will be 14.7/1.1 or 13.36."

EQ Ratio isn't the same as commanded lambda.

[Dave_In_VA]

From the Editor description for EQ Ratio: "[ECM] 12400 - Power Enrich EQ Ratio: This is the main table that is used to tune WOT fuel. The values in this table are Fuel/Air multipliers (or Equivalence Ratio) ie. values greater than 1 are richer, values less than one are leaner. The values relate directly to the Stoich AFR and the resulting commanded AFR is Stoich divided by this PE multiplier. Eg. if the multiplier is 1.1 then the commanded AFR will be 14.7/1.1 or 13.36."

EQ Ratio isn't the same as commanded lambda.

@pannetron

Thank you.....

[pannetron]

If your wideband is accurate, it's reporting ~0.84 at a commanded EQ ratio of 1.130. That commanded EQ Ratio equates to a lambda of around 0.88 so you are running a little richer than commanded. Other than a little rich at WOT, IMHO that log looks really good. Stoich for 0% ethanol gas is 14.7 but more ethanol reduces that.