I'll keep my fingers crossed.  You keep yours near the Backup select switch just in case :>)

 

Tracy

On Dec 21, 2007 8:10 PM, Mark Steitle <msteitle@gmail.com> wrote:

Tracy,

I ran the engine at various rpm today and tried to duplicate the MAP table failure and could not.  I tried keying the mic with and without the transponder on and the engine running at various speeds.  I tried various combinations (IDENT, Standby, ON) and couldn't duplicate the failure.  

So, I relocated the diode from #1 terminal of the SSR to the anode side of the injector diodes, grounded to the water pump housing.  Then I installed the two 1uf capacitors to the output terminals of the SSR.  I then ran the engine and it performed well, so I decided to test fly it.  Again it ran fine, although it needs a little fine tuning around idle speeds.   I will take care of that tomorrow. 

I plan to fly quite a bit over the next two weeks, and I'm optimistic that the problem has been resolved (how's that for positive thinking?).  I'll let you know if this is not the case. 

Thanks for your expert help,
Mark
12 hrs and counting...

On Dec 20, 2007 8:00 AM, Mark Steitle <msteitle@gmail.com> wrote:

Tracy,

 

The injector diodes are physically located near the injectors.  So, if I understand you correctly, the clamping diode should be under the cowl close to the injector diodes (anodes).
 

I plan on going out to the airport tomorrow and plan on doing the radio test then.  I'll let you know how it goes. 

 

Thanks,

Mark
 

On 12/20/07, Tracy Crook <tracy@rotaryaviation.com> wrote:

Hi Mark,

Don't think the added diode was ever anywhere else on the schematic but a lot of info gets tossed around on email, phone calls and error, misunderstandings can happen.  In this case, I'm not sure what the result of having the diode on the other side of the switch would be, maybe nothing.  I don't know where you physically located the series diodes in the injectors so location of the added clamp diode depends.  It should be somewhere close to where you tied the 3 anodes of series diodes together.  In general, keep wire lengths to a minimum.
 

Any results from the radio tests?

 

Tracy

 

On Dec 19, 2007 7:51 PM, Mark Steitle <msteitle@gmail.com> wrote:

Tracy,
Thanks for the schematic.  Did the placement of the diode change from an earlier version?  I currently have the diode attached to the SSR.  I'll move it to the other side of the DPDT switch.  Or, should this be closer to the injectors? 

Also, I'll pick up a couple of capacitors this weekend and install them between terminals 1 & 2 of the SSR and ground.  Hopefully, that will cure the problem. 

Thanks for your help,

Mark

On Dec 19, 2007 4:59 PM, Tracy Crook <tracy@rotaryaviation.com> wrote:

The schematic shows the added diode (cathode) connected to the junction of the three series diodes of the secondary injectors (where the 3 anodes connect together).  This junction IS tied to one pole of the injector switch but NOT tied directly to the SSR.   I'll attach the schematic again. 

 

I don't have a schematic showing the capacitors.  I suggested them as a troubleshooting measure for the suspected noise problem you are seeing.  They may or may not have any effect.  These two capacitors would go from the output pins (1 and 2) on the SSR to ground.   Value would be anywhere in the range of .1uF to 1.0 uF at 200 volts or more.   
 

Tracy
 

On Dec 19, 2007 5:22 PM, Mark Steitle <msteitle@gmail.com> wrote:

Tracy,

Yes, I have installed the diode you sent when you last upgraded my EC-2.  It is connected from the secondary injector switch terminal of the SSR to ground (going from memory here).   I don't recall seeing a schematic which included capacitors.  Can you provide a schematic on this?

 

Thanks,
Mark

 

On 12/19/07, Tracy Crook <tracy@rotaryaviation.com > wrote:

Mark,

  That was an additional CAPACITOR I said to add, (actualy 2 capacitors).  One from each SSR output lead to ground. You said you already had the diode shown on the schematic, right?

 

Tracy

 

On Dec 19, 2007 3:47 PM, Mark Steitle <msteitle@gmail.com> wrote:

Al,

 

What I don't understand is why am I just now having this problem.  I've been flying for 11 hours and this problem just recently surfaced.  The only change I remember doing recently was replacing the electro-mechanical injector staging relay with a solid state relay.  Tracy has recommended that I add a second diode from the second output terminal of the SSR to ground. 

 

I will try that, but I will try to reproduce the failure (on the ground) by triggering the radio, and also turning the transponder from off to standby to on.  The transponder is the closest piece of electronic gear to the EC-2.  As I understand it, the transponder also puts out much more wattage than the nav/com.  

 

One more possibility is that the tach lead coming from the EC-2 is unterminated.  I have since learned that it is bad practice to leave wires unterminated.  So, I will remedy that this weekend too.   

 

Also, I would like to know where the best place would be to connect a scope lead on the EC-2 to look for noise.  That seems like the easiest way to track down this problem.  I will ask Tracy for suggestions before proceeding with the scope. 

 

Mark S.

 

On 12/17/07, Al Gietzen <ALVentures@cox.net > wrote:

  I have separated the injector wires and the coil wires from the rest. There's a ground block located between the two with a connection through the firewall to another ground block and engine ground.  Batteries are in the back though.  There's a #2 welding cable going from the ground block to the battery.  It routes down the right side away from all the smaller wires. 

When you say "smaller wires" do you mean current carrying wires that power things, and return current from the alternator – or just instrumentation wires?  Good practice, especially in a composite plane, is to use twisted pair (power/grnd) to cancel noise. Having power leads away from the ground return forms a big loop antenna for radiating EMF from wires that carry noisy current. I suspect that is not much help at this point.

 

Probably the noisiest wires we have in our planes are the alternator output and the power for the coils and injectors.

 

The nav/com is mounted near the EM-2 and could possibly be the culprit, based on Al's recommendations.  The EM-2 display is right above the nav/com.  Maybe I need to move the nav/com to the back of the plane? 

 

The Nav/Com itself should not be an issue, the antenna lead should only 'leak' low levels of RF unless the impedance match isn't good, or bad connection to the antenna.  Is your EM2 display remote from the Data Acquisition Module?  Those leads, the serial leads between the EM2 and EC2, and the power leads to the EC2 should be kept away from the noisy wires.

But then, I'm no expert on this stuff.  Tracking down electrical noise takes an expert with an oscilloscope.

You were on a good track suspecting the solid state relay if the problem did not occur prior to installing it. You may need to add snubbers there.  Switching relays definitely generates a noise spike.

Al

 

 

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