flyrotary@lancaironline.net Mailing List Archive

I may be giving the impression that the manual is perfect and if only the builder would read it, all would be well. This isn't the case for many reasons.

For one, every installation is different and the manual mainly reflects my own experience. When I get feedback from builders (which I highly encourage! ) I add details which may apply to other installations. That's why there is no hard and fast procedure that will apply to every installation. Hence my prodding builders to fully understand each programming Mode and apply the appropriate one at the right point.

For another, the manual AND the controller is constantly being updated with new things and procedures. Mode 2 has been completely redefined in recent years and Mode 6 was added about the same time.

There are now over 20 versions of the manual and it has become a nightmare keeping them all synchronized and up to date. So if it doesn't explain something properly, don't hesitate to point out errors and missing details.

About the staging point, I need to carefully read and analyze what Steve is seeing. The staging point has gotten very complicated over the years due to the addition of the RPM map and the changing method of defining it. For you guys digging really deep into the EC2/3 operation, be aware that there is hysteresis in the stage point so it will not be at the exact same point when throttling up as it does going down. It is also defined as a map table address instead of an absolute manifold pressure, but only when above the active RPM based table. Even I get confused here until I review it carefully.

Mode 6 may be necessary even if you have identical injectors. This is because the on and off times of the injector is not the same.

That's all for today's dissertation on EC2/3s :-)

Tracy

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On Tue, Feb 17, 2009 at 12:29 PM, sboese <sboese@uwyo.edu> wrote:

Tracy,

I have always wondered why so many people seem to have trouble with staging, myself included. My setup uses all four injectors of the same part number and the flow rates and dynamic ranges are very well matched as demonstrated on a flow bench.

As you know, I am in the process of retuning my system after an EC2 upgrade. When looking at data logged from the EC2 at less than 1 second intervals, there appears to be an inconsistency in the manifold pressure corresponding to the staging address and the manifold pressure the EC2 reports when staging actually takes place. In my case staging will take place with the manifold pressure reported by the EC2 up to 4 In Hg less than that corresponding to the staging address. So far I have not seen the system stage at the manifold pressure corresponding to the staging address.

Is it possible that the EC2 is actually staging at a lower manifold pressure than that set in the staging address, using the mixture correction table value at that lower address, and when the manifold pressure rises sufficiently, the correct correction table addresses are used again? With my mixture correction table, a significant increase in table values is required just above the staging threshold. If the above were happening, the mixture would go very lean when the EC2 staged and used the values in the correction table lower than the staging address. This is what I see on the O2 sensors when there is a problem staging.

I hadn't tried to change mode 6 settings since I am sure my injectors are very well matched and the manual indicates that in this case mode 6 changes shouldn't be needed. Your message brings up the thought that if the above is happening, one may be able to use mode 6 to obtain a mixture correction table where there is no or very little change in table values for addresses in the region corresponding to the staging point and a couple of inches of manifold pressure below that. Then it wouldn't matter exactly what manifold pressure the EC2 actually staged at or the actual correction table value used since the mixture would still be close to correct. Mode 1 or 9 may still be able to obtain correct mixtures outside this region. Is it possible that those who have no staging issues have stumbled on this type of mixture correction table accidentally?

Crawling back into my hole to continue to RTFM.

Steve Boese

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Tracy Crook
Sent: Tuesday, February 17, 2009 9:30 AM
To: Rotary motors in aircraft

Subject: [FlyRotary] Re: Second flight

Again, it is very important to understand what is happening. Without this understanding, a builder is working in the dark.

Fuel delivery is not doubled when the EC2/3 goes from staged (2 injectors) to unstaged (4 injectors). The controller cuts the pulse length to about 1/2 when this happens so the net effect on fuel delivery is very small. The amount that does change should be tuned out by using Mode 6 PRIOR to any MAP table tuning. See the previous message on this subject.

When in doubt, RTFM! One caveat. The manual has been updated many times over the years. If you don't have a current edition, feel free to ask for a MS Word copy of the manual via email but be sure your controller has been updated to match the documentation.

Tracy