Changing K vs injection pulsewidth

[Torque]

Out of interest:
When I change K which represents the injector size, why doesn't the Estimated Pulsewidth in NT change?

[Matt]

Estimated pulsewidth is based purely from a themoretical calculation where 0.125 x filtered value of the fuel map (from memory). It is not an actual pulsewidth of the table since the table itself is just a multiplying value

The 'real' pulsewdith is calculated by the ECU as explained at the start of my training notes:
https://www.nistune.com/docs/Workshop%2 ... %20Web.pdf

When Nistune was originally written, it was based from the Japanese ROM editor which used the same calculations. I've wanted to remove this (and the estimated AFR) since it confuses new tuners, but the old school tuners use the values so I have to leave them in ... even through they do not reflect actual ms/AFR due to variations in K/TIM and other enrichment factors like coolant temp

[Torque]

Thanks for the explanation,

Interestingly the values in the pulsewidth table are very close to actual values I get from the logs.

How would one have to tune without an AFR table?

[Matt]

Use the wideband (or the Trace window)

Usually we tune doing the following
1. Adjust K constant until get full use of the fuel map
2. Adjust TIM until cruise mixtures are 14.7:1 (with near 0% STFT/LTFT)
3. Tune fuel map with the 'filtered values' window and adjust these values until we get the required AFRs on the wideband/trace window

[Torque]

Hmmm ..

I don't have TIM, so as far as I remember the procedure was to adjust K till A/F ratios are in line with what the wideband shows?

[Matt]

Without feature pack, yes you need to use K instead of TIM and then adjust TP scales afterwards

[Torque]

I you knew how much air (in weight) went through the AFM at what voltage you could better estimate injection times/AFR.
But I guess that data is not available...