IGN precision & How does ECU compute value from table?

taitcw · Post by **taitcw** » Fri Aug 28, 2009 3:18 pm

Hi Hondata,

I have a general tuning question.

Let's say for Low Speed Ignition 40deg table:

@ 4500rpm, 87.3kPa (Col 8) = 31
@ 4500rpm, 98.8kPa (Col 9) = 28

@ 5000rpm, 87.3kPa (Col 8) = 32
@ 5000rpm, 98.8kPa (Col 9) = 27.5

If the MAP read 92.8kPa and engine is running @ 4892 rpm,
how does the ECU work out the the requried IGN from the 4 values given?
Does it use simple linear interpolation? What's the algorithm like?

Also, what's the resolution of the calculated IGN like? Round down to the nearest degree?

Thanks,
DT

Post by **Hondata** » Sat Aug 29, 2009 1:08 pm

Linear interpolation. Don't forget that it also interpolates between the cam angle tables too, so it is actually using 8 values. Ignition uses a 0.2 degree resolution.

taitcw · Post by **taitcw** » Sun Aug 30, 2009 4:14 pm

Thanks for confirming that. Very good info!

Does the IGN value show in Sensor window get rounded down to the nearest degree?

Would that be possible to show the IGN in full in Sensor window?