Only time to hit the high points before hitting the road (wish I were flying :)  Main thing is, once you have identified a problem,  don't keep flogging away at other symptoms until you have fixed the one at hand.  I am assuming your analysis of the non responding mixture control is correct.   Mike and John may be correct when they say that you could be so far out of tune that the mixture control is not having the expected effect, but this is rare.

 

BUT, all the symptoms you are relating scream that the mixture control is not connected to the EC2.   This leaves a floating voltage to the EC2 so the mixture will drift around like a ship without a rudder.  This makes ANY attempt to tune or fix other problems a waste of time and counterproductive.  Fix the mixture control problem or determine whether it really is a problem befor doing anything else (with the engine).

 

To test the mixture control itself, with the power on, and the panel connected to the EC2 measure the voltage at the top pin of the pot.  It should vary from zero when fully CCW to +5 volts when fully CW.  It should vary smoothly when between these extreams.  Don't short anything out during this test, use a little spring clip or insulated aligator clip when taping into stuff liker this.  Don't just jam a meter probe in there which can easily slip and short things out.  (been there, done that). 

Last hint.  The mixture * CAN NOT * make the engine run faster than normal idle.  You have an air leak somewhere.  Find it.  I assume it is not the idle setting on the TB?  But do this after the mixture control has been fixed.

 

Tracy

On Thu, Jun 12, 2008 at 10:58 PM, Christopher Barber <CBarber@texasattorney.net> wrote:

I have got my work cut out for me. I went out to the hangar.  The good news is the engine not only started, but started a all my few attempts.  If you remember from previous episodes my old engine (the one that leaked coolant into the chambers) would tend to start once and only once a day (or several hours time past).

 

My newly built engine is starting consistently.  I played around with the timing a bit and hopped the CAS a tooth to get it to align a bit more in the center of its turning area. It didn't seem to make much of a difference yet, however, I am still having trouble with the Mixture Knob. It is not making a difference for the A or B controller.  I have checked the d-sub connection on the PCM and the wire from ECU pin 26 to PCM pin 15 and they all seem to check fine.  I will need to climb in the back of the plane to check the connection at the ECU but I ran out of time tonight.

 

I am currently getting some strange actions from the computer.  I can start the engine with B if the cold start switch is on.  I switch to A and it want to die, turn of the cold start switch and it smoothes out nicely.  If I start in A, it needs the CSS off.  If I started in one and switch to other, it seems to want to die so I switch back, shut down then restart in the other position and it will want to die when changed.  Also, when in B, I killed the primaries and it kept running....cut the secondary's and it wanted to die.  When I tried it in A, it would want to die when the primaries were shut down.  The engine is running pretty fast too.  About 1700 rpm ish.  I have checked for intake leaks in a preliminary manner and will do so more when I get to the hangar again.   I don't know how much of this may be attributed to the mixture control not working.  I also seem to be getting oil flow, but I am having some problems with my oil pressure sensor...sure don't want to be running with bad oil pressure. So, this is some bad with the good.

 

Gawd, I hate consistent inconsistency. ;0

 

I am a bit frustrated,buy hey, I got the dang engine to actually run based on me building it with new parts with a medium street port.  Yeah, I want to get past this stage, but at least I am moving forward.......kinda.  I think my next step will be to verify all my wire runs.  I broke one of our cardinal rules and I changed more than just one thing at a time.  I re-terminated some of the wires due to there extreme length.  I had to do something while I waited for parts from Mazdatrix and Tracy. <g>  On that note, as of now, my PSRU does not seem to be leaking any oil.

 

So, what say y'all??????

 

All the best,

 

Chris

 

-

From: Tracy Crook

To: Rotary motors in aircraft

Sent: Wednesday, June 11, 2008 8:29 AM

Subject: [FlyRotary] Re: First Start - AGAIN

Never seen an EM2 freeze up but then I've never left it running over night (not that it should hurt anything).

 

When you say that the mixture knob made no difference, did you mean that the mixture monitor did not respond or that the engine did not respond to a change in mixture (egt change, sound of engine, etc).   Assuming for the moment that the engine did not respond, the first thing to try is the backup controller.  Did you try it?   Did it act the same?  If it did act the same, it is VERY unlikely that two controllers have failed in the same way at the same moment in time.  (have you ever heard me say this before?  :>)  The obvious place to start is the wiring between front panel and EC2.  Specifically the wire from pin 26 on EC2 to pin 15 on the front panel.  (see instructions)   Are they connected?  Are they shorted to ground? 

 

Tracy  (Colorado bound)

On Tue, Jun 10, 2008 at 12:46 PM, Christopher Barber <CBarber@texasattorney.net> wrote:

Ahhh, the joys of engine development. After fiddling with getting the timing set (thanks to y'all for this info) I was able to start my new engine.  I ran it for a few minutes while checking for leaks etc.  I was thrilled it started again.....however........

 

I found one leak coming from the top of the engine where I had a heater hose inlet sealed off.  It was tapped out earlier but only clamped closed so I installed a bolt with some sealant on it and recovered it with a end hose piece and clamped it shut.  This proved a better choice.

 

The larger concerns are this.  When the engine started the Engine Monitor was on, and I kept a diligent eye on it. After a couple of glances at it in the cabin while looking at the engine I realized that the monitor was not "monitoring".  I grabbed my handheld laser temp monitor and pointed it at the engine and temp was still ok.  At first I just noticed the RPM was not regersting (my first thought was I was gonna get the NOP signal), then that the temp was not moving.  After shut down, I turned the monitor off and back on and instantly the monitor started working again.  Hmmmmmm.  The monitor was mistakenly left on overnight and I am guessing it "froze up" during this time, but I would have not thought leaving it on would have done this.  It also worked on my three subsequent short starts. Of course my hope is that this was an anomaly, but will stay aware that it did happen. 

 

However the biggest problems follows. When the engine started it was running a little fast, but did not seem too bad and I throttled back and it slowed a bit. When I noticed that the monitor was not processing data I grabbed the mixture knob and turned it to slow the engine and to see if it made any difference.  Damn, the mixture knob was not doing ANYTHING.  NOTHING.  Turning it from left to right made no difference.   Damnit.  I cut the fuel at this point, too many issues.  BTW, the prime function, cold start switch and A/B inputs all seemed to work and would make a difference when operated.  But not the mixture knob.

 

After letting the engine cool a while (the temps did rise pretty fast per my hand held laser temp gage and I was pushing 220 after several minutes on a hot/humid Houston summer day) I restarted to see if the engine monitor was working.  It was. However, the mixture know was not.  I re-checked the other inputs and they all worked.  The engine was running pretty rough......gee, the mixture actually makes a difference <g>.

 

After shut down I disconnected the batteries (I have installed master battery cut-offs) and then the control module and ECU and checked the wires between the two.  This was just a quick continuity check and the wire was good.  I then took a meter and in my non electrician mode attempted to check the actual knob.  I place leads on the two prongs that seem to be soldered to the control board and turned the knob.  The numbers changed up and down as expected when I turned the know....so it seems that the knob itself is not the culprit, and the wire seems ok.  What else should I check and/or try?  I kinda need the mixture control to work.

 

Is there a way to test to to test to determine if this knob is actually doing anything when the engine is not running??????

 

Of course my timing sucks as Tracy is about to hit Colorado..  So any solutions y'all may be able to provide should prove especially useful.

 

I anxiously await y'alls response. 

 

Maybe I should just go ride my loud motorcycle to think thinks through. <g>

 

Thanks again.

 

All the best,

 

Chris Barber

Houston