Intermittent rough running and RPM drop

Update. Yesterday it ran great no problems 4 hours. I do not understand how the sticky throttle valve could have caused the rough running, that is the only thing that was wrong and odiously needed to be fixed. These must be related but I do not understand why and will end this with the assumption they are since both happened at the same time.

Anyway, at this point this is closed for me now unless any new event happens. For anyone out there, we can gain knowledge that the throttle valve rotation/spring should be lubricated and perhaps a stronger spring would make it last longer before sticking.

UPDATE

After running about 7 hours normal operation the low RPM and vibration came back and more odd things happened.

Was Flying at remote airport MEV in my trike, also 912iS, and I heard a radio call from my other instructor in the SLING 2, same airplane earlier incident happened, she had vibration and was going to land at the remote airport. I met her and her student there on the ramp. Same as before, pulled the cowl off, wiggled all the wires, put the cowl back on and decided to attempt to fly the Sling 2 912iS back to my home airport CXP about 12 miles away .

Takeoff fine than about 300 AGL RPM dropped to 4200/4300 and vibration again, but the vibration was not as bad as before and the RPM was slightly higher. With me solo and reduced weight I was able to constantly climb at average 200 FPM.

Did some tests by switching off lane A, no change. Switching off lane B no change. Reduced the throttle to idle and everything normal. Throttle back up to full and still low RPM/vibration still. Did both lane checks and throttle reduction 3 times to verify results/tests over the airport. Same.

Continued the slow climb up to an altitude where I could glide back to my home airport and the RPM started to go up slowly to full throttle and everything was normal. It took about a minute or two for the RPM to increase from 4300 to full RPM.

Back at home airport did some touch and go’s everything normal. Perhaps 20 minutes of flying locally, everything normal.

Back to the dongle and BUDS program to download the data. The irritating long typical download and nothing in the BUDS program. Zip file was about the same size as previous downloads 5 to 6 MB, but no data in BUDS, totally blank. Looked at the ZIP files Lane A and Lane B CSV files, with plenty of data but nothing in the BUDS program. This is another issue so I am going to start a new topic about this.

This is a tough one to diagnose so I will just throw out some ideas.

From your troubleshooting it sounds like the ignition is OK so that leaves fuel and air.

It's a long shot but make sure your fuel tank vent is not blocked or partially blocked. 

After that,  to eliminate possibilities, check your fuel filters and air filter.

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

Jon Tensfeldt wrote:

This is a tough one to diagnose so I will just throw out some ideas.

From your troubleshooting it sounds like the ignition is OK so that leaves fuel and air.

It's a long shot but make sure your fuel tank vent is not blocked or partially blocked. 

After that,  to eliminate possibilities, check your fuel filters and air filter.

Jon,

When I was flying it back and the problem WAS happening, I switched fuel tanks for a long enough time that I could tell both fuel tanks were OK and the course filters in the fuel line out of the tank before the fuel switching valve were good. Switching tanks did nothing. However, the fine filter is possibly a suspect so it will be changed.