When do secondaries kick in?
 

When do the secondary injectors kick in?
When my S4 RX7 had a stock ecu, the secondaries kicked in around 2800 rpm.
With the rx8, there are 4 secondaries as opposed to 2--when under what conditions do those secondaries kick in.?

It depends on load.
In a NA car the secondaries (outer yellows on an S1) come at 3700 and the p2s (inner yellows)around 5000 .
On a boosted engine the earliest Ive seen is : secondaries 3200 and P2s 4300


It has always been stated on here that the secondaries come on before the p2s.
However , some testing I have done suggest it's the other way around . I haven't said much about it because I haven't tested this to get a 100% definitive answer.

Actually it’s always been stated that way in the Mazda technical documentation


https://cimg9.ibsrv.net/gimg/www.rx8...4a901a6603.jpg

I don't think that chart is a a very accurate representation . For one thing the secondaries start at 20% duty not zero . For another the primaries don't go any higher than that first peak after they drop down when the secondaries kick in.
The reason I had doubts about which was first is because of the way you can hold the ssv shut and it doesn't seem to affect fueling till well after the secondaries are supposed to kick in .

Here is a log of P1 pulse width vs rpm from my turbo 8 where loads are reaching 200%.

https://cimg2.ibsrv.net/gimg/www.rx8...328a54d67b.jpg

And here is P1s from an NA


https://cimg5.ibsrv.net/gimg/www.rx8...59a4297cbd.jpg

I just pulled that offline and am not 100% sure where it came from, seemed to mirror my recollection

but this is straight out of the 2004 service highlights manual. Even if only a generic representation it still states that P1- Sec - P2 is the sequence


https://cimg2.ibsrv.net/gimg/www.rx8...3dfdca890d.jpg

Yeah , have seen that one too . I just can't understand why I can run the ssv closed to 4300 and it's only then that the fueling goes south . Any thoughts on that Team ?

You mean with turbo? Well the SSV is not fully sealed or designed for pressure as opposed to vacuum. I’d also expect some fuel to dribble out the port despite the lack of full flow through the port. Just a few guesses, can’t say for sure :dunno:

This is some awesome information I never knew, regarding the 3rd stage of injection.