Cadillac XLR LH2 Tuning VVT Tune 6E – MAF adj, Baseline

For Tune 6E I returned to Tune 6B, except I further corrected the MAF signal in high frequency to a smoother curve.

xlr Tune 6E Maf adj compare 6B

Click to zoom in, back to return.

Today’s run in blue, comparison best run 6B in red.  These have the same setting except for the MAF tuning.  The blue is lower than the red in mid and high rpm.

Today’s run was a big hit with the airflow, and with the calculated hp, in hotter weather, with more weight in the XLR (gas).

xlr tune 6e comparison with 6b

I am not sure why that doesn’t translate into a better measured performance, which is what I expected to see.

I am taking 6E as the current baseline (tuning is identical to 6B) and will run more baseline tests to check.

XLR 6E vs 6B O2 voltages -- 6B is 10 mv lower

Narrow band O2 meters are notoriously poor at reading exact AFR, but the 6B was running 10-15 mv lower on each side than the 6E.  This suggests the XLR is running richer in 6E than in 6B.  This could be the effect of different days, or it could be that with the MAF adjustments in 6E vs 6B the PCM recognized the higher airflow now and is adding more fuel to get to 12.5:1.  So although closer to commanded now, perhaps the XLR would prefer 12.8:1 again?


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