Terrence,

 

Test the induction system for leaks.  The rubber hose type seals where the air distribution system leaves the sump are the most likely candidates, although the gaskets at each cylinder can break down also.

 

Make sure that the adapter and plug anti-seize is appropriate. Stuff such as the Permatex silver colored goop can foul plugs to the point of misfiring.  Use something like the Champion black antiseize.

 

I believe the difference between the Plasma II and III ignitions is that the III system extends the duration of the spark and that can help less than perfect ignition conditions.  Perhaps you should re-check the timing with a light.  Do you have the optional display that allows you to check MAP, RPM and timing?  Loose timing data wires (can cause misfiring) or bad RPM and MAP data to the Plasma controllers could result in erratic ignition.  Do you have the crank sensors or the mag drive sensors?  The connectors to the mag drive sensors are, uh, not, uh, perfect.

 

While the ignition can be a bit off and still result in apparent OK operation, the F/A ratio is most critical with induction system leaks being most evident by poor operation at low power. Misfiring leads to plug fouling.

 

 

 

Almost ready to aviate, but taxiing with engine that has been getting increasingly rougher, even after overhauling the Bendix RSA and testing the Plasma II CDI ignitions okay.  En ine sat for years, labelled preserved, but for about 5 years not run  after complete rebuild by Performance Airmotive about 8 or 9 years ago. 

Now, taxied and othrwise run-up for less than  3 hours, is becoming increasingly less inclined to idle.,

Initially would idle smoothly down to about 650-700rpm...

Then the lower plugs fouled/carbon and oil...replaced with new plugs at 2 hrs.;

then in another hour of ground running, runs strongly at 1500-2500 rpm, and when below 1500 mostly aggressively lean, still the bottom plugs again fouled in less than an hour, and minimum idle speed increased to about 900 rpm, running so rich it fouled plugs even with agressive leaning... suspected fuel injection servo had dried and cracked diaphrams, having sat dry for many years, so had it overhauled (Kelly)...

Ran it two days ago, and the minimum idle speed without competely cutting out, was 1000 rpm. Runs strong at higher rpms.

Will run a compression test tomorrow.

I want this mill to run perfectly before I fly it.

Any comments or suggestion welcome.

Terrence

L235/320

N211AL KGRE

 

 

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