we aren't 100% sure what exactly is wrong with the engine, we have several symptoms:
1. CHT's and EGT's we have higher temps on #3 (which is often the case with these engines) but the real problem is that we set up the engine in cruise and not 10 minutes later one of the temps will change significantly (not talking the usual small changes because of lift/sink)
2. Fuel flow irregular - at a specific power setting fuel flow will jump around, pressure is stable at around 24psi, when you put on the electric fuel pump fuel flow goes up briefly and then settles at a LOWER fuel flow than it was reading before
3. irregular starting, I know the injected engines can be tricky but usually you can figure out a system that works, we keep having to figure out new tricks.
4. irregular full power rpm at take off
5. irregular Manifold pressure readings, and unusually low manifold pressure readings
6. higher fuel flow readings than we should be getting for this engine - as mentioned above also irregular
7. leaning is no an even process, you can screw out the mixture, temps slowly climb, then suddenly within a ⅛th of a turn the CHT starts climbing and won't settle till it is 40+ºF higher, I know there is always a "hump" after which it gets a lot more sensitive but this seems extreme to me.
so now you will all be saying to yourselves "but many of those symptoms can be a myriad of other problems", and I agree.... but many of them point back to an irregular fuel delivery into the piston. which is why we have decided to get at least ONE element on the engine looked at and reset to where it should be and then start going through the checks again, otherwise we will just be chasing our tail forever.
we have already done the following:
- correct baffling, now we have relatively good control over our CHT's and can keep them under 400, which wasn't the case before
- corrected lower cowl outlet - now developing enough differential pressure to cool
- moved oil cooler to behind #3 on the baffle and turned oil cooler around (both pipes came out bottom of cooler) so it can self bleed any airlocks - oil cooling now much better (we know that this might be part of the reason why #3 cyl is 20ºF higher CHT than the others, but at least now we have stable CHT and OIL temps.
we have subsequently found a company in South Africa (only 800 miles away) that has parts for our Bendix RSA5AD1 fuel servo and we have shipped our unit to them, then at least we will have one element that should be reliable. will update what the result is when we have it back in the plane.
@Skywagon8a - our full power fuel flow indicates 58-62ltr/hr (15,5-16,5Gal) on our G3X and we have had our nozzles cleaned in a ultrasonic machine and tested them, their delivery is not exactly the same but we have our fuel divider sent in with the servo to be checked.