Using MS2/Extra, I am working toward a blended tune with alpha-N controlling the low end, and SD modifying the high end. I've just about got the alpha-N working perfectly across the entire power range. The biggest issue I'm having right now is some strange cranking behavior.

I've experimentally determined that the engine wants about 12ms of PW during cranking when it's 80 degrees outside. The req_fuel is set to 9.5, so the Cranking Pulse set to 120% at that temp should give me the 12ms I'm looking for. I'm using 1 squirt per engine cycle, simultaneous injector staging

Instead, I get 18 or so ms for several cycles and then it drops to just under 5. Eventually, it will jump back up to 18 and the engine will start up and run smoothly, but the entire process generally takes about ten seconds.

What is producing the sub-5 ms PW?

 

I think I may have found the issue.

I switched to simultaneous injection a few weeks back, so that I could do some stanging...hoping that it would improve my idle. I didn't switch from the number of injectors from 4 to 2 at that time.

Since my cranking PW was about half of what it needed, this would make sense.

 

Unless you are using timed injections, with each primary injector on its own channel, you need to use 4 injections per cycle. This is because each rotor ingests air twice per cycle, offset by 180 deg, so there are 4 intake events per cycle for a 2-rotor. If you want to be sure that the same amount of fuel is being delivered for each intake event, you therefore need to use 4 injections per cycle, since both primary injectors are on the same channel (with channel 2 driving the secondaries). This should help your starting, idle, and low to mid-load a lot.

Simultaneous vs Alternating doesn't make a difference for rotaries, since channel 2 only comes on for the secondaries (at high loads, flow rates etc), so its timing relative to the primary injection isn't very important. In fact, in rotary mode I'm not sure if this setting actually even does anything.

 

You must set simultaneous. Weird things will happen with alternating and staged injection (if the code doesn't already give you a config error when you do that).

Ken

 

Tuner Studio won't let you select staged with alternating selected; hence my switch to alternating. I now have it set for two injectors, because I have two injector BANKS, firing simultaneously, four times per engine cycle.

With that, the req_fuel is 9.5, producing a base PW of 4.75. With the cranking PW set to 120%, this would produce the ~5ms PW that I see while cranking. I think the real solution to my cranking problem is to move the cranking PW up to over 200%.

 

What generation 7 is this on? If you have primary & secondary injectors (stock FC & FD setup), then injector channel 1 needs to be wired to both primaries, and injector channel 2 needs to be wired to both secondaries, and you need to use staged injection. If you don't, then you'll be firing the primaries and secondaries for each rotor at the same time, and at low-load & idle, you won't be able to control the amount of fuel finely enough, since you'll be barely opening the injectors & will have a very inconsistent opening, spray pattern, and thus amount of fuel delivered and amount of mixing.

Basically, if you're running primary & secondary injectors, inj channel 1 needs to be wired to both primaries, inj channel 2 needs to go to both secondaries, you need simultaneous injections, 4x per cycle, and staging set.

 

The only other point is that the number of injectors should be set to 2, because it really isn't the number of injectors. It is the number of injector banks. Correct?

 

Yes, number of injectors should be 2, but thats because there are only 2 injectors on the primary channel, which is used for calculating req_fuel. The other 2 injectors are accounted for in the staging split correction value

 

toplessFC3Sman is correct. You should be connecting injector channel 1 to both primaries and injector channel 2 to both secondaries and running sequential.

 

With the suggestions from this thread, I understand where my numbers for PW are coming from and I'm able to manipulate them to get the number that the engine wants. Not only is it running smoother from idle to WOT, but it is making more power along the way. I've gone from maxing out at around 5100 to yesterday when I hit 5640.

Time to finish the sand-and-fill work on the left wing, and then start the high-speed taxi testing.