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m/s fuel maps

Understanding AFR

Discussion and questions related to the course Understand AFR


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hi guys where can i get more info on doing a millisecond fuel model , as i understand the ve part of the course but im stuck with an older ecu that only uses a ms model

Tuning in MS is absolutely not different than VE.

VE is just a ratio of the "base" opening time, so it really easy to convert from one to the other method.

base time (in ms) x VE = opening time (the value you would have in a ms based ECU)

PS: m/s (meter per second) ≠ ms (millisecond)

my bad on the typo ,

There are a couple of ways that an ECU can implement a millisecond based fuel table. One method which is employed by Haltech, Pectel and Life Racing is to directly enter the actual injector millisecond opening time into the fuel table. The other option which is used by the likes of Link/ViPEC and MoTeC is to use a base millisecond pulsewidth as a type of scalar for the overall fuel delivery. The numbers in the fuel table then become a percentage of this master or base pulsewidth. Often with this system the ECU will be applying a background compensation to the fuel delivery based on manifold pressure (and any other comp tables in use such as IAT/ECT etc), which has the effect of flattening the table numbers somewhat.

Regardless which system you're tuning though the actual tuning process is the same - Doubling a number in the fuel table will double the fuel delivery. you can also apply the correction formula of 'Measured/Desired' to calculate a correction to apply to the fuel table value to get your AFR where you want it to be.