15 minutes into a leisurely 50 minute return flight from across the border (WI/IL border) I experienced what felt like a sledge hammer whacking the plane – A big misfire of old reliable up front.  Not to worry, once or twice a year these things happen at night, over water or in the mountains – Slug of water (I did top off in WI)? Fiberglass shard going thru an injector? Or just a mysterious happenstance?

 

Now that I am alert, another occurs, then another, etc.  About 15 random times over the remainder of the trip – With my hand poised over the “nearest airport” function, noting that at 5500 feet I had maybe an 8 mile engine out range (there is a high airport density in this part of the country), I repeatedly ran thru the engine/ignition instrumentation looking for anomalies – none were noticed.  I did reduce power somewhat and the misfires seemed less “noisy.”

 

The investigation began the next day after things cooled down, checking the obvious things first.  Let’s see, no water in the fuel so the cowl was pulled and the experimental injector air supply system was checked for blockages.  Then, the LSE timing sensors (mag accessory gear driven) were examined and the right d-sub connecter was LOOSE while the left one was not tight.

 

Hmmmmm……………………..

 

In a long-ago conversation with Klaus, I noted that these connectors had loosened up after just a few test flights and he had mentioned that some users had put a tie-wrap around the connector to keep the hold-together screws from backing out and that the exiting wire had to be supported to something that shook with the engine.  So I did that.  At OSH I talked again with Klaus and suggested that if the Hall sensors had pig tails the connectors could be isolated from vibration.  He said “Yes, you can do that.”  There was no hint he would ever change.  Note that the LASAR system uses very nice locking connectors at the end of a 10” pig tail.

 

Anyway, I was sure that the loose connections I found could cause bad timing information and subsequent misfires.  I was not going to have that happen again – especially since I had only 20 hours since these connections were last secured with the tie wrap scheme.

 

So, I bought replacement metal connector covers (Mouser Electronics) with stemmed hold downs that I drilled for safety wire.

 

 

The one on the left is the LSE supplied metalized plastic cover with wee hold down screws.  When I disassembled it, even the cable relief clamp had come loose.  The metal one on the right has different sized hard rubber relief clamps and, also note the drilled thumb screws.  Medium strength thread lock (blue) was applied to the screws that hold the case halves together.  Mouser's write up indicated that metalized plastic covers had a 30 Db noise rejection rating whilst the metal ones had a 70 Db rating, another positive.  

 

Here’s what the left one it looks like with the thumbscrews safety wired in place:

 

 

 

Yesterday, a 1 hour test flight went smoothly – no hiccups, no sledge hammers.