Lean at WOT, not following target AFR

[mrQQ]

Hi,

so long story short: the car does not target the AFRs I have set. Stock tune, I have set OL WOT AFR targets starting with 2500 rpm to 0.68. Looking at logs, it only targets that value after 5k RPM. What is going on?

Also, is "desired lambda" actually what ECU is calling for, or is it just a copy of actual lambda?

[mituc]

the Desired Lambda/AFR is the lambda/AFR ECU is targeting for. Keep in mind that the ECU may target a different AFR than what you have in your tune because there are a lot of other aspects ECU is altering the AFR based on: SWAS, BATs, magnitude of the KR, ECT, and so on. However, the AFR targeted by the ECU is usually richer.

The AFR differences you are experiencing may come from the fact that the OL and CL tables are not correlated near the OL-CL transitioning curve. What I'm saying is that if the tune targets, say, 13AFR at load 1 and 2500rpm in CL, and 11.5AFR above load 1 at the same RPM, and the CL to OL transitioning condition is load above 1 then you may see a pretty high AFR difference both because of this lack of correlation as well as because of the turbo spool - that assuming that the MAF cal is spot on.

I checked your log especially in those areas where the load was above like 1.2 and the actual and desired AFR pretty much match. It looks to be a bit too rich at WOT (around 10AFR/0.69lambda, while you're saying you saw it's lean. Can you please let me know the line numbers you're looking at?

[Steve @ VersaTune]

Actual AFR not matching Desired AFR at WOT is often due to MAF calibration or some other mechanical issue related to air or fuel metering.