Hi Al,

 

I might be able to add a little here.  I had the "snubber" mod done to my EC-2 and it totally fixed the idle mixture problems.  I haven't fouled a plug since getting the upgrade (I have a workbench full of fouled plugs which I hope to be able to clean and use).  

 

Another mod I had Tracy do was to change the EC-2 over to the Renesis style crank-mounted CAS.  That maybe wasn't one of my better decisions.  It took lots of testing and finally hooking it up to a scope to get it de-bugged so that it would run up into the higher rpm ranges.  I ended up adding a 22K resistor in the CAS lead, and a 6.2V Zener diode/620 ohm resistor combination te'ed to ground to clip the voltages down to something the EC-2 would accept.  I was hoping to get a more reliable system by using the crank mounted sensor rather than the gear driven sensor.  I believe the signal is more stable, but I'm not sure the circuit is superior.  We'll have to wait and see.

 

Best I recall, my coil disable switches work as they should, i.e. engine slows when shutting down either.  But is slows more when I disable the leading coils than when disabling the trailing coils.  I haven't tried it at high rpm though.  

 

I don't know if it "auto-leans" with altitude as I haven't flown yet.  I'll have to watch that closely when the time comes.  Also, will have to check mode B to make sure engine still runs.  I haven't tried copying A to B since the last upgrade as I have been afraid to mess up B as bad as I did A.  Actually, it is running pretty good (better than ever before) on A, so now might be a good time to try copying A to B.       

 

I do suspect that my auto-tune feature isn't working (could be operator error).  It was supposed to have had the auto-tune upgrade done a year or so back.  But I go through all the steps described in the manual but the mixture doesn't seem to change.  

 

Hope this helps a bit, and thanks for the update,

 

Mark S. 

 

  

 

On 7/11/07, Al Gietzen <ALVentures@cox.net> wrote:

Further to my last posting on the subject; we did the following changes to my 20B EC2

 

1. reduced values of the added caps for noise filtering on the ignitions circuits by a factor of ten.
2. replaced the MAP pressure sensor on Controller "A"
3. added what is being referred to as the 'clamping diodes' or 'snubbers' on the injector circuits.

 

Changing the capacitors had no noticeable effect on what I believed was a timing issue.  I still find that at low power disabling leading coils has definitely more effect than disabling trailing; whereas at high power, say about 19" MAP and above, disabling the leading has small effect and disabling trialing has larger effect.  I have concluded that the timing is not late with both on; since I found that now retarding the timing a 2-3 steps (4-5 degrees) at power increased the rpm a bit. I think the larger caps did result in a small retarding of the spark.

 

Does anyone else with a 3-rotor, and using the LS1 coils, note the same behavior when disabling leading/trailing ignition?   Tracy mentioned that on his 20B using the renesis coils, disabling either set results in the engine stopping, so there may be something amiss in the circuitry.

 

I thought that the strange leaning of mixture with altitude when running on controller A was solved by replacing the pressure sensor – until I got over 5000'.  Then over the next 200 ft increase the mixture monitor bar on the EM2 went slowly off the bottom of the scale, and it took turning the mixture knob to about 3:00 position to return it to a mid-scale reading.  Switching to controller B gave me a momentary scare – the engine quit, well completely lost power for the fraction of a second that it took to switch back to A. More on this below.

 

Adding the snubbers on the injector circuits resulted in quite a different profile on the mixture table settings.  It also resulted in smoother running at low rpm, and seemingly easier tuning to get smooth transition from 'low' to 'high' table, and across the stage point (or maybe I'm just getting better re-tuning). 

 

One thing I had discovered when re-tuning was that, apparently due to powering up the unit on the bench to check the MAP sensor, resulted in the injector pulse setting (mode 3) to get set to a much lower value, and the stage point to someplace out of range.  The engine would only run with the cold start switch on.  Once I got those things straightened out, things proceeded smoothly.  When I had all well on controller A, I did the copy A to B. Prior to flying, I had not checked running on B. (OK, it's on my check list, I just bypassed it.) After the episode in the air I figured out that B was acting like A did before the retuning. I tried multiple times again to copy A to B; but it did not take.  I had to manually retune B to get things running right.  Don't know what, but the copy A to B is not working.

 

Didn't mean to run on here – am I boring anyone yet J?

 

Expect to fly tomorrow for some air pressure measurements on the oil cooler.

 

Al