Brian,
If mode 4 is at the default setting and the engine ran smoothly on just the secondary injectors when using the backup procedure, it seems unlikely that there is a significant difference in flow rate between those secondary injectors.
It might be useful to set modes 1, 4, and 6 back to factory defaults and set mode 3 at a MAP just below the staging threshold. The reason for this suggestion is because when MAP becomes higher than the staging threshold, there is the effect of the mixture going lean due to injector lag. There is also the effect of the mixture going rich due to bringing on the larger flow rate secondary injectors. It just so happens that with 28 lb primaries and 40 lb secondaries, these two effects very nearly cancel each other out if the engine is running in the neighborhood of 4000 RPM and using about 6 gal/hr. With a default table and higher fuel flow rates than 6 gal/hr, the injector lag effect will gradually tend to make the mixture richer. The excess fuel flow rate will be about 10% by the time a flow rate of around 14 gal/hr is reached. This richening tendency can then be compensated for using mode 1 or 9. No guarantees, but it may be worth a try.
Do you happen to know at what RPM staging occurs on the ground and in flight? Do you also know the fuel flow rates under those two conditions?
Steve Boese
No, I don't have a secondary injector failure as far as I know. Several points- I had the injectors cleaned and flow tested. Primaries are 28 #, secondaries 40#- the engine
is a 13bREW- 93 twin turbo, but normally aspirated. I checked to see if all the injectors were firing by disconnecting all the other leads and running on mode 1, engine off and press program switch. They all are firing. Also ran the injector backup proceedure.
The engine runs well on the ground all through the power band, but in the air , after staging it is a bit rough and misses. My theory- the secondaries are not firing equally and need to be tuned in mode 4. The engine stages normally at MAP address 84, and transistions through that point pretty smoothly, and runs very smooth below that point. That's why I think I need a bit of rotor matching in mode 4 above the staging point using the EGTs.
I feel that I am making definate progress.