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912iS issues w/ running rough and lane light


Animosity2k

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So I already spoke w/ Corey a bit tonight but wanted the insight of some others. Tonight on the ride home from a trip from CFG to PIT I experienced a popping feel in the rudder pedals. I was travelling around 107kt @ 7500ft. Immediately the lane A light turned on and the Rotax Land Aircraft Immediately warning appeared. When I landed I did a run up and cleared the Lane A light but the plane still sounded and felt like it was running rough. I taxied to hangar and entirely shut down and restarted. Lane A light went back on as soon as I blipped the throttle and it still sounded and felt rough.

I spoke to my mechanic whom is on another airfield and he has no way of helping me out where my plane currently sits. The field I am at has no Rotax mechanics on site. I pulled the cowling and checked everything and with the exception of a loose spark plug boot on Cyl 3T everything seemed connected fine. 

Does anyone have any ideas? I am going to get a compression check done before I even try to turn it over again at this point however once again I am stuck at a field with no one here to perform a compression check for me as they have no experience on this engine. Is there a manual or something I can send them that goes in detail on how they can do this for me?

Also, this light tends to come on fairly often, it just never runs rough. 

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6 hours ago, Eddie in NC said:

Same thing happened to me in your plane. One of the spark plug wires had come loose inside of the boot. Might try checking them all.

Eddie, my AP drove over from his airport this morning. The 3T Cyl spark plug boot was really wobbly (noticed this last night self diagnosing). They took the boot off and the wire inside was beyond corroded they said and apparently the mechanic said it looked like theres a little wood screw holding it all together inside the boot that had came loose. They tightened it all back up and started her up. Ran rough for a few minutes, then it got running fine and they were able to run it up for 15 minutes without any issues!

Would you guys recommend just replacing all the wires? Are there better ones then the factory ones?

Eddie how often did this happen to you when you owned the plane? Any other quirky things?

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23 minutes ago, Eddie in NC said:

I thought that might be the problem. It only happened to me one time and it was the front left cylinder. I put it back just like it came off but with no screw.

Is the front left on the PIC side? Thats the side I had an issue w/. I'm going to try to just replace all the wires in hopes of not running into this. Does anyone know roughly what I should pay for cables? Hearing about $400 seems a lot...

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The cable ends do screw on to the cable, at least the old style does. A little dielectric grease helps. I wouldn't replace all of the cables, just the one that is causing the issue. I would first check to see if there is any extra length, and if there is trim a 1/2" of the end and put a new terminal on. That would be at the most 1/2 hour labor and a $15 part. For the old style spark plug boots you will have to go to another source besides Rotax. I recently purchased  some off Amazon.

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2 hours ago, Eddie in NC said:

Yes it is on the PIC side front left. That sounds like way too much for cables. Someone on here might know better than me but looks like you could just get good quality automotive cable and make them up.

Eddie this is the same cable/boot I had go bad again. Did you just trim and rescrew the cap back on last time? Do you know if this plane has the newer or older boots? 

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Animosity, I'm confused.

You said your problem was with the lead on "Cyl 3T". That sounds like the top plug on the right rear cylinder (the aircraft's right and the aircraft's rear). Eddie said his problem was with a boot on the left front, which is cylinder 2, without saying top or bottom. It doesn't sound like you're talking about the same cable.

Mike Koerner

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7 hours ago, Mike Koerner said:

Animosity, I'm confused.

You said your problem was with the lead on "Cyl 3T". That sounds like the top plug on the right rear cylinder (the aircraft's right and the aircraft's rear). Eddie said his problem was with a boot on the left front, which is cylinder 2, without saying top or bottom. It doesn't sound like you're talking about the same cable.

Mike Koerner

Mike, I could be mistaken when I said 3T. When im standing on the PIC side of the engine w/ cowling off, its the top right plug on the rectangular horizontal block that say 912 on it. I'm not at all a very mechanically savy person. Tech yes, mechanically no. 

I think I will just replace them all at this point just to be safe. I asked my AP to cut the corroded part out and just replace the boot but they said they are not comfortable doing that. Especially since I mentioned this had happened to the past owner. 

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The cylinders are numbered starting at the propeller end of the engine, with 1 and 3 on the Right side and 2 and 4 on the left side. It sounds like you are looking at the ignition coils where the other end of the lead attaches. For those familiar with the 912 ULS, the 912iS is set up different.

For your A&P cutting the end of the wire and replacing the terminal end is normal procedure. That is basically what he will be doing if he replaces all of the cables. Changing all of the wires and terminals with new is going to lead to unneeded extra expense. For example you will have to switch to the new spark plug boot, which means you will have to switch to the new spark plugs. The new spark plugs cost almost 10 times more that the plugs you currently use. At most just replace the offending cable and ends, and keep an extra section of cable and ends if it happens again. I might go to the trouble of unscrewing all of the ends and trimming all of the wires and reinstalling all of the terminals. 

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Tom, are these Sport Ignition wires different then non sport? CPS only lists one from as far as I can tell?

https://www.cps-parts.com/catalog/rtxpages/912isignitioncables665-558.php?gclid=EAIaIQobChMIo_r74de_5wIVE9bACh0slAvqEAQYAyABEgKQfPD_BwE

 

I know in my logs somewhere it shows my airplane had a "sport upgrade" done to it at some point, I would imagine at that point it may have got the new plugs, boots and wires?

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20 minutes ago, Tom Baker said:

The Sport upgrade did not change any ignition components as far as I know.

The ignition systems are different between the ULS and iS. Without looking up parts l don't know if the actual cable is different. I do know that they use the same cable end for the spark plug.

Thanks! My AP called me said he already ordered the new wires and they were around $300. I did find them on CPS and Leading Edge Airfoils for only $230.... not sure where they got the parts. I didn't realize nor do I think they realized we need now all new Spark plugs & Boots... @ $40 a boot and $25 a plug this is going to be a super pricey thing to do. 

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Following this trail, clearly the wires & boots are identified as problem.  Curious if you have examined what the plug electrodes look like, if you're burning 100LL fuel, and would lead fouling also be a factor?  Maybe not, especially with 2x plugs per cylinder, just thinking when I do run up / mag check I notice virtually no difference in engine smoothness and that's at 3k RPM, why would one lead create a rough running engine, could be more to the story here?

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1 hour ago, Animosity2k said:

Thanks! My AP called me said he already ordered the new wires and they were around $300. I did find them on CPS and Leading Edge Airfoils for only $230.... not sure where they got the parts. I didn't realize nor do I think they realized we need now all new Spark plugs & Boots... @ $40 a boot and $25 a plug this is going to be a super pricey thing to do. 

They may plan to reuse the boots and plugs. If you have to replace a boot you will need to find a source outside of Rotax, or make the switch. The old style boots are available under the NGK part number.

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45 minutes ago, GrassStripFlyBoy said:

Following this trail, clearly the wires & boots are identified as problem.  Curious if you have examined what the plug electrodes look like, if you're burning 100LL fuel, and would lead fouling also be a factor?  Maybe not, especially with 2x plugs per cylinder, just thinking when I do run up / mag check I notice virtually no difference in engine smoothness and that's at 3k RPM, why would one lead create a rough running engine, could be more to the story here?

Not sure, I also normally do not get any rough engine running when doing my Lane Check. 

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8 hours ago, Eddie in NC said:

The problem that I had was on the left front cylinder. The top spark plug if I remember right. Unless they were changed  after I sold it to the gentleman you bought it from they are the old style plug wires.

Eddie I circled which plug / boot I have issues w/ is this the one you spoke of?

cyl4t.jpg

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To gain access behind the Dynons remove the whole panel. That can be done by removing the perimeter screws and setting the panel out. It's pretty easy, and will only take a couple minutes. You shouldn't need to unhook anything, just let the panels hang. You might want to protect them with a towel.

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