Target Lambda/AFCMD discrepancy

[Truedeal]

This is on a 2009 CU2 using Flashpro manager 4.2.1.0.
In an attempt to salvage a little more fuel efficiency I set my Target Airfuel ratio to 15.3, and my closed loop Lamda target limit is an airfuel of 15.90, my closed loop target at low load is also 15.3.



The problem is the ecu won't actually target my low load targeted airfuel ratio. It will target 15.3 for approximately 10 seconds after startup and then afterwards it always defaults to 14.7 for the foreseeable future. I'm currently using my AFM for fueling, but I have the same experience whether using AFM or MAP.

[Truedeal]

I have more information regarding this to elicit a response.
The ECU is a 37805-RL6-E540, with an attached calibration

I have posted two data logs, the first one is just a engine off to engine start datalog, you can at about 16 seconds the AFCMD switches from the value I have defined in the closed loop lambda section to its own 14.7 that its pulling from somewhere.

The second datalog I have live tuning enabled for "Closed loop target lambda limit", and "Closed loop target lambda low load". The vehicle was already running for about 30 seconds prior to starting the datalog which shows the commanded AFR is 14.7. What is interesting is that if I increase my "Closed loop target lambda limit" during live tuning and then reduce it the AFCMD will try to temporarily use my defined value in the lambda limit table but it always defaults back to 14.7. At 27 seconds into the datalog I set my Closed loop target limit to 16, and reduced it again to 15.7 to see the ECU listened but once again defaults to 14.7 2 seconds later.

[Spunkster]

Try the attached calibration. It may not work to do what you are trying to do.

[Truedeal]

Try the attached calibration. It may not work to do what you are trying to do.

Hi there, I've attached a datalog using the provided calibration.
The vehicle behaved the same , you can watch the AFCMD initially target 15.3 and default back to 14.7 around the same amount of time post startup.

[Spunkster]

If you want to save on gas I would say that WOT air fuel tables are the way to go. Going leaner on non WOT lambda tables the ECU does not let happen because it's bad for the engine.

[Truedeal]

If you want to save on gas I would say that WOT air fuel tables are the way to go. Going leaner on non WOT lambda tables the ECU does not let happen because it's bad for the engine.

So it is not possible to run above 14.7 AFR while cruising?

[Spunkster]

The ECU doesn't like to. It can run richer, but not leaner.