We have done a few Custom OS modifications on various controllers. The E38 is one of them.
That controller is very versatile, but there are tiny nuances that got corrected on the E92 — such as the ability to change IAT retard based on E85+. That is available on the E92, but not on Gen IV controllers like E38 and E67.
We took that into our own hands and added the table.
E85 is a lot more resilient and not as sensitive to temperature. If your calibration is correct, there is no need to pull the full retard.
This particular OS is 12653249, but we have ported it to most. These are the small things we add to customer calibrations when needed.
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