Intermittent rough running and RPM drop

Rotax-Owner wrote:

Paul

Does your aircraft have a Garmin or Dynon? The ECU doesn't record fuel PSI or Fuel flow, and I think it would be good to look at this data. This information would be stored in the Garmin or Dynon that can be extracted.

Also, when was the last time the fuel filter was changed?

You said the issue went away after jiggling some wires? Pin 11 is for the fuel pump and sometimes it has a poor connection that can result in fuel pump issues. - (See this link) https://www.rotax-owner.com/en/912is-technical-questions/8245-x1-connector-pin-failure

The Aircraft has MGL panels which do not record fuel pressure or fuel flow, I don't think. During the time I was doing the slow climb out with the problem happening, I did keep a close eye on the fuel pressure and it was maintaining the typical 40 PSI normally. My fuel pressure sensor on the Sling is after the fuel filter which I do not like. On the aircraft I installed fuel pressure senders/pressure, I installed it BEFORE the fine filter. It reads about 70 PSI before the filter and when it gets up to 80 PSI I know it is time to change the filter. Much better design in my opinion.  

Any way I did a number of tests switching fuel tanks, no effect. Now that you mention it I should have looked at fuel flow. Darn.

Yes the fine fuel filter is a suspect so it will be changed.

Pretty sure fuel pumps are OK because during the event I did switch both off the main and aux independently and no change. I am going to check pin 11 as suggested since I am doing EVERYTHING I can.

UPDATE

First, I want to thank all responders for taking the time to comment. I really appreciate it. It really makes me think about all the perspectives.

This is what I actually since the last flight when I had the problem. Went back to my BUDS files that I did have and noticed that there some EGT error on Cylinder 1, not for the event, but before that. So I keep a new spare EGT prove handy and swapped it out. Additionally went back and cleaned all the EGT connections with contact cleaner. Blasted them.

I figure bad EGT probe/reading could trigger such an event.

During my climb out, during the event (low RPM at WOT and vibration), I noticed that the EGT's of cylinder 2 and 4 were noticeably lower. Not by much but noticeable. I gave the fuel tanks a heavy dose of sea foam to clean any fuel injectors that may be plugged.

Today we got 6 hours and it ran great. We are extra cautious with our flying and making sure airports are close by until we get more time.

UPDATE

About 15 hours now assuming my EGT probe replacement fixed it.

Still do not understand why bad EGT would trigger such an event.