[Richard L]

I just read your forum discussion.

WOW... so much!

My assumption is the fluctuation of the AFR and power readings were skewed due to uneven methanol distributions to the cylinders. The distribution is greatly affected by the position of the jets. It is especially significant if methanol is injected in large quantities to supplement fuel.

The cylinder distribution vs jet position is frequently discussed in the BMW 335 N54 forums. The his engine has two lambda probes for each of the 3-bank cylinders. Logging the STFT (Short Term Fuel Trim) has highlighted the importance of the meth jet locations. They spray 100% methanol to supplement fuel.

Here is the long term consensus that all agreed:
(Initial discussion started just like your forum)

1. Close to the TB, large STFT deviations in the two banks
2. At the exit of the IC, the deviation is down to +/- 5%

The argument regarding the methanol trapped upstream of the TB is a valid argument but so does the charge air. Onset of methanol injection is normally under boost so the delay due to distance is minimal as air/methanol is travelling at supersonic speed towards the cylinders.

Since the discussion, 90% of the methanol tuned N54 have move their twin 1mm nozzles to the exit of the IC. No more discussion surfaced since.

I will try look for links to this STFT topic with logs.