The good news is the engine runs! Having said that, this is all extremely uncharted territory, and if it wasn't for Lynn French, I would be completely in the dark. Lynn is the character that first installed an electronic fuel injection and ignition, in his Tri-Q-200.
I used Bosch 24 lh/hr. fuel injectors, sometimes referred to as "blue tops". These are the same size that Lynn uses and it seemed like a good starting point. The ECU is programmable and you can adjust the fuel flow to your own particular application and injectors. When we first got it started, it was extremely rich. I mean rich, to the point where there was black smoke plainly coming out of the exhaust and now there are two major soot streaks running down the belly.
The first few times I ran it, it was kind of a sensory overload; all these new dials, buttons, and the like, to learn. And, it seemed like some features worked and some didn't. It was, and still is, a lot to sort out.
There is a fair amount of programming of the controller to do. The idea is to first match the basic flow of the injectors to the engine, then to map out the mixture tables.
Adjusting the mixture is interesting. First, instead of a mixture knob that you pull out, there is a mixture dial on the Programming Control Module (PCM). You use the dial for tweaking, but you use the Program Variable, Mode and Store controls to make your adjustments permanent. (Over simplification, really).
To adjust the mixture, you really can't use the conventional EGT. We welded a bung into one of the exhaust stacks and have installed a Bosch automotive oxygen sensor. This is connected to a gauge in the cockpit and it provides a digital presentation if the mixture is rich or lean. This gauge reacts much faster than a regular EGT and is easy to interpret. The first sensor I bought didn't work very well, so I bought a better one which has it's own heater.
The O2 sensor is temporary. They are designed for unleaded fuel and after a while 100LL is said to clog them up. I only need it though, for the initial mixture mapping. All of this is so new to me and there is so much to learn. Sheesh!
After a while we (C-Rod and I), came to the conclusion that the programming button wasn't working. Now, we may be mistaken, but we think we have it right. Anyway, after lots of diagnostic e-mails, back and forth, with the controller designer/manufacturer, I pulled the unit and am returning it for evaluation.
I will say that the engine starts easily, and seems to run fairly well, considering. There are lots of unknowns here, I have an automotive racing throttle body, homemade induction system and lots of seat-of-the-pants engineering, so I am taking everything in stride.I guess I'll work on my taxes while I wait the outcome of the controller.
No comments:
Post a Comment