Posted this because someone asked me about the jerky response they are getting now that they are running split injection. Ie they are using a small injector for slow running and a large injector for power. I think the issue is in the size of the step on the map at the point where the ECU changes from the small injector to the larger one.
The Ecotrons Alpha-N map is not a fuel map but a map of predicted changes in engine load (torque) with respect to TPS and RPM.
It is like a stair case and to keep the Load steps even, it is possible to cluster the rpm steps around the area of rapid changes in Load (torque). And on my dyno graph that is 7,500 to 9,500 rpm (yellow line). Above that the power goes up with rpm but the change in Load is a lot flatter. So you can have quite wide rpm steps below and above where the engine comes onto the pipe and cluster the rpm steps where the Load (torque (yellow line)) curve climbs rapidly so as to have even predicted Load steps across the complete rpm range from 3,000 to 13,000.
Ie on my map the first rpm point is at 3K rpm, the second is 6k the third is 7k then 7.5k, 7.75k, 8k, 8.5k, 9k and rpm step 9 is 9.5k step 10 is 11k then 12.250 and finally 13,250 rpm. So the spread of rpm points is chosen to get even changes in the Load steps.
My TPS steps are 0, 10, 12, 15, 18, 20, 26, 31, 36, 41, 46, 51, 61, 71, 85, 98. there is much greater changes in air flow at low TPS than there is above 70%. If you look at the dyno graph everything above 70% has pretty much the same power output.
What I think happens when split injection does not work properly and jerks all around the place is that when the small injector gets to a load cell step that is to big and would max it out the ECU swaps to the big injector which squirts to much fuel for the rpm (because the min on time for the big injector flows to much fuel) and the rpm drops back below the small injectors last effective load cell and the air/fuel clears and the rpm slams backup and the cycle violently repeats itself. Now a smaller big injector might help but a disparate size in the load steps can be the real problem.
This will not be confined to a set rpm position on the map but a patch of Load cells where the effective differences in predicted Load is to great. And I expect the ECU's hysteresis between injectors will play a part here too.
The trick is to group the RPM columns and TPS rows in such a way that the changes between adjacent Load cells in any direction are much the same.
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