Still thinking about your symptoms and solution.   Idle MP on a PP engine will normally be higher than stock but your earlier MP of 17" Hg is way out of the ball park.  Stock is in the range of 11 - 12 depending on rpm.  17" is  where my 13B engine runs at economy cruise!  My 20B is at even lower (15.5 - 16) and will maintain level flight at 14.2" Hg! 

So,  that along with your check valve results make me wonder if you ALREADY have a leak in the MP plumbing creating artificially high MP readings.  I had this condition when the MP sensor in my Bluemountain EFIS went bad and started leaking.

 If the check valves and your plumbing are leak free, it definitely would NOT WORK.   Have you ever tested the plumbing?  Just disconnect the MP line at the engine and suck on the end and see if the system holds the vacuum.  If not, you have a leak.

Tracy

On Fri, Jan 20, 2012 at 10:13 PM, Mark Steitle <msteitle@gmail.com> wrote:

Charlie, 

The reservoir idea is the next thing I'll try if this doesn't work out.  But so far, this looks good.

Mark 

On Fri, Jan 20, 2012 at 8:15 PM, Charlie England <ceengland@bellsouth.net> wrote:

Assuming well designed intake & exhaust manifolds (& substantially equal MAP in each rotor measured at the same intake position of each rotor), do you need 3 feeds to one sensor? Have you tried using just one, with a small air reservoir for 'inertial damping' (averaging) of the fluctuating MAP on that line? I'd expect that the computer is taking 'snapshots' of MAP, & if there's no plenum to give it an averaged pressure to look at, then the snapshots would be all over the map (pardon the pun...). Also, I assume that there's no way to force the computer to take its snapshot a user-selectable point in the intake cycle, right?

Charlie

On 01/20/2012 07:02 PM, Mark Steitle wrote:

Tracy, 

OK, what you said just registered in the grey matter.  Any ideas on what to do if the MAP does't come up fast enough resulting in bogging?  Calibrated air bleeds?

Mark

On Fri, Jan 20, 2012 at 6:46 PM, Mark Steitle <msteitle@gmail.com> wrote:

Tracy, 

Thanks, I'll check that, but remember... I've got three of those "suckers" and they're working overtime.

Mark  

On Fri, Jan 20, 2012 at 5:27 PM, Tracy <rwstracy@gmail.com> wrote:

Sounds like it's working for you but if those check valves are "good" ie, don't leak,  the MP won't go up fast enough at the EC2/3 port and the engine will probably bog down and die when you open the throttle (especially if done rapidly)..   Check your throttle response to be sure the EC2/3 sees the true MP when you go to WFO.

Tracy

 

On Fri, Jan 20, 2012 at 6:04 PM, Mark Steitle <msteitle@gmail.com> wrote:

I made a major breakthrough today.  In preparation for hooking up my new Hytek data logger, I decided that it would be a good idea to install check valves in the vacuum lines leading from each rotor housing.  (For those who are unaware, I am running a peripheral port 3-rotor with a slide throttle TB.)  My system measures MAP from the unused oil injection ports in each rotor housing.  Not sure what possessed me to do a ground run right then, but I decided to do a ground run after installing the check valves.  Now keep in mind that typical MAP readings at idle up to this point was approx. 17".  This has been bugging me, but it didn't stop me from flying.  Well, today's MAP readings were in the 14.4" - 15.0" range.  Then it dawned on me that the way the vacuum lines were plumbed the EC-2 would see an average of all three rotors.  Since each rotor is 120* (crank degrees) apart in their 4-stroke cycle, the MAP would be quite a bit different for each rotor.  By installing check valves in the vacuum lines, I have now isolated each rotor from the other two and am measuring the lowest vacuum.  Idle is now down to a respectable 1500 rpm, but the mixture has gone way lean, so it appears that a re-tune is in order.  I'll probably re-set the EC-2 to the factory defaults and start the process over from the very beginning.  

I would like to strongly suggest to anyone that is measuring MAP in the rotor housings to install check valves in each of the lines.  Your EC-2/3 will thank you for it.  

Mark