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Discuss all things tuning in this section. News, products, problems and results.
What do we do if customers Injector brand doesn't provide small low pulse width table?
Do we just compensated from the Target AFR map ?
Here is a really important concept to consider - A few years very few tuners in the standalone tuning market knew what a 'short pulse width adder' was. About 15 years ago few people knew what injector deadtime was and some ECUs didn't even compensate for it (some sadly still don't).
Now we have an ever increasing amount of data all aiming to increase the accuracy of our tunes. Each additional parameter makes increasingly smaller gains in this accuracy. Don't get me wrong, it's all great data and it does improve the situation but we also managed to tune cars and get quite acceptable results when we didn't know this stuff existed or couldn't utilise it even if we had it.
So in short what I'm saying is if you have the data then use it. If you can find the data then hunt it out and use it. If however you don't have short pulse data, set this table to zero and be happy in the fact that your engine will probably still run quite happily. You will end up tuning around the non linear area of injector flow with the numbers in your fuel / VE table and it may end up looking a little funky as a result.
If you're reflashing a factory ECU that includes a short pulsewidth adder table then this does present a larger problem as you usually aren't tuning a fuel table or VE table as such and hence can't fudge these tables to account for the injector linearity. In this case the ECU is relying on the input from the MAF sensor and the target AFR table primarily. The result of not having the correct short pulse width adder data is that the closed loop system may end up working slightly harder at low pulse widths to achieve target. Unless you've got a really terrible set of injectors though, this shouldn't present a large issue though. Also remember that the non linear area of flow typically only extends to 2-3 ms so you are only going to be in this area at idle and very low rpm / light load.
My advice would be try it and test the results to see how the car performs. If you can't get an adequate result explain this to the customer and what the implications will be. It can then be their decision as to whether they source the right data/better injectors or accept the results.
Got it thanks