Quote:
Originally Posted by ASAP
How does the JB4 on the F80 scale / bias fuel? I am going to guess it can't because the fuel tables are written and once you encroach the threshold of the fuel trims, it goes lean.
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You guessed wrong
The lambda target has a fuel trims competent and when the S55 trims go positive it actually targets richer instead of leaner. The more positive the trims the richer it goes. It actually misfires when AFRs get to around 11:1. So by locating the fuel trims positive or negative you can effectively set the AFR target. Of course, this can only be done with CANbus data where the JB4 reads the current AFR and fuel trims.
The JB4 also has a second mechanism for setting fuel targets in the form of an o2 sensor signal bias. Although this isn't used yet on the S55 as it hasn't been needed. It's there ready to go if/when it is though.
Mike