Hight Altitude crossover point

[racemonkey]

Does anyone know what the crossover point is where "high altitude" maps take over for Spark Advance?

I'm just under 1000 ft elevation and it seems like the WOT spark advance is closer to the high altitude table(s) than the base table(s).

[ninjawarrior821]

No idea, but I think it's effecting me to at sea level.

[RaraK69]

not positive, but interprolation starts around 1500 feet and full values used at 7500 ft as a guess. I see a map, but i dont have the function sheet for these ecu's to give solid answer.

There isnt a straight switchover between the map sets fyi, its going to be interpolated based on a curve essentially.

[VFORCEJOHN]

Helpful tuning hint. In scanner.

Create a timing map using the same exact parameters as shown in the timing map into a table. Same rpm. Same throttle or map or load whatever.

Do this axis copy for BOTH maps especially if they differ or one is based off map and one off tps or load. .label one Low and one high altitude.

Do this in the gear you want to have data on ONLY. don’t sit there and rev in neutral as load values increase timing will also decrease with boost.

Set high altitude to read highest or lowest (not average) values.
Set set low altitude to read opposite of high. Try it both ways.

You’ll then be able to map the exact crossover points out as the data will begin to differ in a 3d fashion vs one throttle , rpm, lid, map value.

Hope this makes sense