----- Original Message -----

From: Tracy Crook

To: Rotary motors in aircraft

Sent: Monday, October 16, 2006 10:06 AM

Subject: [FlyRotary] Re: Coil / EC2 Wiring

Keep in mind that there are entire books written on the subject of aircraft wiring so this will not be an exhaustive answer and there are always situations which I won't think of until something goes wrong (like Al's situation with the remote EM2 display and the EC2 PCM wiring).

 

  The only shielded wire in my system is the alternator cable to the battery (mainly for radio noise suppression) so extensive use of shielded wires is usually not required.  I did use a twisted pair for the crank angle sensor on the Renesis.

 

Here is the general guideline on the EC2 wire routing outlined in the EC2 installation guide that I should go back and expand on, clarify, etc. 

 

 Route the low level control lines (PCM, crank sensor, coil control lines, etc) separately from any high current switching lines (coil power, coil ground, injector power & drive lines, etc). 

 

  That's it.  As stated above, there will always be possible exceptions like Al's situation but 99% of the time this general rule will work fine.

 

Tracy  (back to getting the 20B setup to run for the Rotary fly-in)

 

 

----- Original Message -----

From: Bill Bradburry

To: Rotary motors in aircraft

Sent: Sunday, October 15, 2006 8:35 AM

Subject: [FlyRotary] Coil Wiring

Tracy,
I have both my harneses (EC &EM-2) soldered up and ready to be routed.
I would like to do this once and correctly...:>)

I have two firewall penetrations, one on the pilot side going to the
injectors with the injector control wires bundled together.  I had
planned to bring the injector power wires thru this same penetration
bundled together, but not bundled with the control wires.  If I need to
do any twisted pairs, exactly which pairs should be twisted together??
How far apart should the two bundles be?

The other firewall penetration is on the copilot side.  I currently have
the balance of the EC-2 wires bundled together and going thru this
penetration.  I also have all the EM-2 wires bundled and going thru this
same penetration.  This includes therrocouple and temperature sensor
wires.  Sounds like I need to separate some wires.  If so which wires
need to be separated and  how?  Do I need more penetrations?  Exactly
which wires need to be twisted together and or shielded??  How far apart
should the bundles be and if they are together (penetrations) how far
can they be allowed to be close?

Thanks,
Bill Bradburry




Mark; Tracy;



I'd like to explore this further.  Mark S wrote:

After reading Bob Darrah's post last week where he noticed a big
improvement after separating the leads to his coils I gave it a try on
my 20B.  It made a big difference, but was most noticeable in the lower
rpm range.  I was only able to separate the wires down near the coils,
and then only by a small amount, but it made a substantial improvement.
My question for Tracy is, can I leave the grounds and +14v wires bundled
together and only separate the trigger leads, or do I need to separate
all the wires?  Also, if I were to use 3 individual shielded wires and
ground the shields, could I then bundle the trigger leads together with
the rest of the coil wires?



On a side note, after separating the coil leads, it took a much leaner
mixture to get it to run smooth.  Before, the best it would idle was
about 1200rpm, now it will idle nicely at 900 rpm, not that I want to do
that, but it shows that the improvement isn't all in my head.



Clarify for me which leads you separated; the control leads from pins 3,
20, and 21 (C-pins) from each other?  I find that below about 1400-1500
rpm the engine begins the occasional miss, and gets progressively
rougher as rpm decreases.  I've been thinking that it seemed more
ignition related then mixture related.



I have the C-pin leads and the B-pins ground bundled together from the
box to the firewall penetration (a few feet). These bundles are separate
for each set of coils (lead, trail).  From the firewall to coils (a few
more feet) the power lead (pin-D) joins the bundle. The A-pins are all
grounded at the coil mount.



Tracy wrote:

1.  How long is the wiring harness between EC2 and coils?

About 6 ft for the trailing and 10 ft for the leading.



2.  How is the power ground to the coils (A terminals) routed?
(hopefully not in the same harness, if so, there is your problem).

3.  Same question as 2. on the power terminals.

Does this say that the power lead (D-pins) should not be bundled with
the C or B pin leads?  If so, is this just as true if the lead and
trailing bundles are separate.



4. I would be surprised if this turned out to be the problem but if
coupling between the control lines themselves (C pins) turns out to be
the problem,  use either twisted pairs or shielded wires to drive the B
& C lines to each coil.  I would lean toward twisted pairs.

I ran a common B-pin ground for each set; bundled with the C-pin leads
but not twisted.  Twisted pairs would mean adding more wires - or would
twisting 3 control leads with one ground to as well?



5.  Are there any other lines routed along with the coil harness
(injector drives, etc)?

The coil bundles run with the injector drive bundles from the near the
firewall to the top of the engine, maybe 4 ft or so; and run with other
wires for a foot or so.  One objective is to minimize firewall
penetrations, another is to maintain separation between sets of
injectors and sets of coils for true redundancy, and another is to
separate noisy wires from quiet wires; so further separating isn't a
simple matter.



Al






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