TP and K are related. The relationship is TP~K*Q/N
where Q is from MAF VQ table, N=RPM, and ~ means "is proportional to". When you open the throttle (add load), Q goes up quicker than N, so TP (load) increases. At a given throttle setting, as N goes up, if Q doesn't change much, then TP goes down. When the throttle is steady and RPM is steady (like when cruising), TP is steady.
TP is the Theoretical injector Pulse width at that Q and N, and TP/256 is the load scale of the fuel and timing maps. When you increase MAF size, MAF voltage drops at the same mass flow rate (Q), so depending on which VQ table you're using, Q also drops. When Q drops, TP drops, so the idea is to increase K until TP comes back into line with your load scales. The calculated TP is multiplied by a factor proportional to the value from the fuel map (at the current cell based on load (TP/256) and RPM), and by other factors, such as O2 feedback fuel trim, etc., to calculate the actual injector pulse width (IPW).
The injector size factor was added by TunerCode so that the actual injector size could be changed, and tuned for, without changing K, which as explained above, would throw your fuel and timing map load scales back out-of-whack. Another reason for adding the injector size factor is that there are actually 3 different IPWs calculated; one as described above using the fuel map, another when cranking, and the 3rd when opening the throttle (like the accelerator pump on a carburetor). The injector size factor adjusts all 3 calculations so little or no other tuning changes should be necessary when increasing injector size.
The problems folks are having are probably when changing both MAF and injector sizes at the same time, which makes getting the TP vs. AFR balance back to normal more difficult. Increasing K increases IPW, but increasing injector size decreases IPW, so the two can "fight" each other.
Dave
where Q is from MAF VQ table, N=RPM, and ~ means "is proportional to". When you open the throttle (add load), Q goes up quicker than N, so TP (load) increases. At a given throttle setting, as N goes up, if Q doesn't change much, then TP goes down. When the throttle is steady and RPM is steady (like when cruising), TP is steady.
TP is the Theoretical injector Pulse width at that Q and N, and TP/256 is the load scale of the fuel and timing maps. When you increase MAF size, MAF voltage drops at the same mass flow rate (Q), so depending on which VQ table you're using, Q also drops. When Q drops, TP drops, so the idea is to increase K until TP comes back into line with your load scales. The calculated TP is multiplied by a factor proportional to the value from the fuel map (at the current cell based on load (TP/256) and RPM), and by other factors, such as O2 feedback fuel trim, etc., to calculate the actual injector pulse width (IPW).
The injector size factor was added by TunerCode so that the actual injector size could be changed, and tuned for, without changing K, which as explained above, would throw your fuel and timing map load scales back out-of-whack. Another reason for adding the injector size factor is that there are actually 3 different IPWs calculated; one as described above using the fuel map, another when cranking, and the 3rd when opening the throttle (like the accelerator pump on a carburetor). The injector size factor adjusts all 3 calculations so little or no other tuning changes should be necessary when increasing injector size.
The problems folks are having are probably when changing both MAF and injector sizes at the same time, which makes getting the TP vs. AFR balance back to normal more difficult. Increasing K increases IPW, but increasing injector size decreases IPW, so the two can "fight" each other.
Dave
Last edited by OnTheChip
on 2016-11-10
at 14-03-30.
Originally Posted by dfddfd2 
.
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