Another Gyroplane Application Question

[Jon Carleton]

I've posted questions before and this forum has been very helpful. We build gyroplanes using Yamaha sled engines. Usually the FX Nytro and RS Nytro 3 cylinder engines. They work VERY well in aircraft.

This is a question regarding a 3 cylinder carburetor model that -probably- came from an RS Nytro, circa 2009.

The problem is an engine that starts easily and seems to run OK at idle, but will not run well above 2500 RPM and begins to surge. The engine sat for a while before installation and had to have the carbs cleaned out to get to this point. We -think- they are operating properly now. Compression is fine. The only real clues we are getting are the codes 21 and the usual hand-warmer code. We can deal with the hand-warmer, and it has never impacted the way an engine runs. All three cylinders are firing. As I said, it seems normal at idle.

I believe 21 is a thermal code, but the water pump is running, the radiator is new and the thermostat is operating properly. There is no indication of a head gasket issue or other leak in the cooling system. Is it possible the computer is doing some kind of "limp home mode" thing because of the 21 code? Or have we missed something else obvious?

 

[HighSpeedLowDrag]

Ensure the throttle override system is bypassed. There is a switch on the throttle lever and another on the throttle. Plug the pair of wires together on the engine side to eliminate this. Codes for handwarmers can be turned off by turning the handwarmers off and restarting the engine.

 

[HighSpeedLowDrag]

 

[Jon Carleton]

We typically put a 10 ohm resistor across the hand warmer leads to stop that error code. We use the speed sensor as a rotor tach to solve the "revving in neutral" issue. When the rotors are turning, it thinks we are moving....odds are we are moving. This engine install and related wire trickery is identical to machines that are working without issues. It still could be a carb problem, I suppose. We were hoping for just a bad sensor for the cooling system or throttle position sensor causing issues with the computer. But if that's not likely, we will have to look at other things.

Thanks!

 

[maim]

have you checked the ohm spec on the temp sensor?

 

[Jon Carleton]

WE SOLVED IT (with your kind help).
The problem was indeed the TORS. Our overzealous builder eliminated some of the wiring that had been provided in the working model, thus causing the TORS problem. I strongly suspect that wire cutters are at the root of the 21 thermal error as well and that investigation is ongoing. The temp sensor does ohm out properly.
The engine is running strong and I may fly the beast tomorrow if the other issues are resolved.

Thanks again!

 

[Jon Carleton]

Ok...so the 21 error is still winning. The wires are intact from the sensor to the computer, the resistance changes with heat, but we still have the error.

The obvious question seems to be, "At what resistance value does the code turn off?" For that matter, knowing the expected range of resistance would be helpful.