Need lean protection using Lambda, not AFR

[gwenthe]

Hi all.

I converted my d16z6 to E85 with bigger injectors and addition of ethanol content analyzer. Because E85 can be 51% to 85%, target stoich can vary so I'm use lambda to measure if lean or rich,

Everything is setup in lambda and working well EXCEPT lean protection. Smanager requires an AFR ratio but since that changes based on ethanol content I want to use a lambda target of 0.85.

I can't really use an AFR lean target as it would be between 12.5:1 (pump gas) and 8:1 (85% ethanol)

Is there some way to set up lean protection parameters to use lambda instead of AFR?

Thanks!

[Hondata]

You don't need to do anything. The AFR is a gasoline AFR with a fixed conversion of 14.68:1 so is not the actual AFR.

You can calculate the true AFR is you wish, but the ECU behavior is the same. It's much easier to do everything as a lambda ratio but the archaic AFR unit is in widespread use.

[gwenthe]

Thanks for reply. I agree lambda is the ONLY way to tune engines using fuels with different stoich.

So to be clear....if I set AFR Lean protection at 12.5:1 then the lean protection will engage for mixture reading above 0.85 lambda? Correct?

[gwenthe]

Hi Hondata,

So to test, I set boost protection at 11:1 (about 0.78 lambda) with load over 5 psi. This means protection should only engage if leaner than 11:1 over 5 psi. Attached is the datalog and calibration. You can see rev limit kick in when boost goes over 5 psi even though lambda is NOT too lean at about 0.85

I then turned off lean protection and ran a test for comparison. You can see boost goes up well over 5 psi and lambda stays below target of 0.85. Please see datalog and calibration.

Any ideas how I can set lean protection to engage if leaner (higher) than 0.84?

[Hondata]

11:1 AFR is 0.75 lambda. At the 11 second mark in the datalog there is a lean cut because the lambda is 0.85 and MAP over the minimum for the cut. Looks ok to me.

[gwenthe]

Thanks for the reply.

So our recommendation is to set at 12.5 (0.85 lambda) correct?

Does that engage lean protection if wideband sees lambda ABOVE 0.85?

Thanks so much for the help.

[Hondata]

Set your lean protection to whatever you want. Just convert the lambda to AFR using 14.68:1