All of my pump gas passes were at ~11 psi...on race gas all we were able to take it up to was ~17 psi, that is when I started to experience the boost control issues, and couldn't go any higher...

850/1680cc injectors ... the highend was hovering around 11.5 afr... duty cycles were in the low 60's ... but egts were creeping high ...

 

here is a datalog of my staging problem.
its around frames 1148-1178 look at pulse widths, rpms, etc.

injectors 550/880
staging point 35
staging off delta 3
staged scaling factor 197

injector delay cycles 25

 

xbox: seems like a bit of rpm noise when your secondaries kick in ... from 3200-3700 ... with a delta of 300, it is kicking on/off. Perhaps try a larger delta (maybe 5+), or find why the noise is getting in there only at that point.

 

There's no afr data in that log, so it's hard to see what's going on. If your scaling factor is incorrect, then you'd go lean as you stage, causing rpm to drop. Back on primaries afr would return to normal, pulling rpm up again, causing staging to occur. Are you sure those flow rates are correct for the injectors you are using?

The next issue is that of running rpm-based staging. If you are running the stock throttle body, rpm-based staging is not the best. If you accelerate gently, its possible to reach the staging point with the secondary throttle plates still closed. When the secondary injectors fire, there is no airflow to pull that fuel quickly into the chamber, so you end up with a bad lean hiccup. Try TPS-based staging set to stage after the secondary runners have opened up a bit.

 

ok ill give that a shot thanx, on wideband my afrs would jump from like 15 down to 24 back and fourth..

 

well, unless you're running an aftermarket FPR, the numbers will be wrong since our fuel rails work at ~38 psi while the testing pressure is ~45 psi IIRC. You just need to hope that the flow in both increases proportionately with pressure, and once you have an AFR trace, play around with the staging number to account for this.

On my car, decreasing the scaling factor by 3 or 4 seemed to mostly cure the AFR hiccup (186 to 182) by making the MS think that the secondaries were smaller than normal, but then it would run a little rich once the secondaries were on. I think i need to work out a balance between this and the map to get things where I want them.

The problem with TPS-based is that I would like to have the option of using TPS with RPM, but the only option would be TPS and pressure which is not only a little redundant, but it would be possible to max out the primaries duty cycle at high RPM low throttle. I know you dont drive in this condition much (if at all), and it would take a bit of work to get to high RPMs under part throttle without hitting boost or opening the secondaries, but i just want to try to keep it bulletproof

 

whoa, it sounds like you're having a pretty bad problem with your wideband then Xbox. You shouldnt really even see 15 afr under full throttle, and 24 would be the engine just coasting. If you're using an Innovate unit, make sure that the black wire (calibrate wire) isnt touching ground or has worn thru, and make sure that the calibrate button is not getting accidentally pushed (stuff sliding around, passengers feet, it getting wedged between wires etc). Then do a new free-air calibration. I had the same problem (before the wires got eaten through anyway :-/) and it turned out that the calibrate button was getting pushed b/c of a shifting bit of harness pushing it against the frame.

 

That's a good point. If those 880's are spec'd at the std test pressure of 3 bar (43.5 psi), then the actual rating at our fuel pressure of 39 psi would be 880 * sqrt(39/43.5) = 833 cc/min. Your new scaling factor would then be 550/(550+833)*512 = 204.

Have you ever actually seen that issue? I've been running that setup for a while on my S5 turbo with no issues and nice smooth transition. There just isn't enough airflow past that primary throttle plate to max out the primary injectors.

 

well my problem isnt at full throttle its mostly just cruising. when i floor it i think the problem goes away.
i will try new scaling factor and see how that works thanx!!
i highly doubt its my wideband.
what would TPSADC value be?

 

You would need to use the "get current" button on the TPS calibration window to see what the value the TPS is at when the secondaries start opening. Adjusted to stock settings, the S4 TPS runs out of range just as the secondary plates begin to open, but im going to try to adjust it to get a little bit of range once they are open already.

I dont know if my primaries are capable of supplying enough fuel for just the primary throttle at high RPM, I havent tested it. I know at about 100 kPa and 3600 rpm, with just primaries on, i was seeing duty cycles of about 60%, so at 100 kPa and 7000 rpm they would definately be maxed out (all else being equal anyway). Now, the question is whether the primary runners could maintain 100 kpa at 7000 rpm, or whether this would drop off due to head loss (i doubt id see choked flow).

Oh, we may want to move this into one of the "staged injection" threads, just to keep things organized

 

Get your own HELP ME PLZ thread remember this one is a post your video thread. Thanks and have a nice day Never mind You can stay with this one I will start a new one. I mean we are on page 3 and we got one video of a great run but tragic ending claimed not to be Mega WHO! Related.

 

Not everyone spends their time videotaping their vehicles. I've been driving MS'd rotaries since the fall of 2002 and have never taken a video clip. Might be a generational thing.

 

Try it its fun. You can send me the footage and I'll edit it for you. I have been driving them since 83 and owned my first in 85. I only wish I had taped them then.