Could use some guidance in troubleshooting a possible Lightspeed ignition issue

[vas4vans]

I bought an RV-10 a bit over 2 years ago with dual LSE ignitions. While trying to chase down a different issue about an oil-fouled spark plug (which I posted on a different thread), I ran a GAMI lean sweep followed by an inflight LOP ignition test and then I repeated it - this was on Aug 3rd.

In the attached chart (which starts at the end of the first GAMI sweep), you can see the ignition test starting at about 00:37:20. After that ignition test, you can see (starting at about 38:30), the EGTs on #2, #4 and #6 climbed above 1400 and stayed there until I started to enrich the mixture. When I leaned the mixture again, they went back up and when I did the ignition test again, when running on just the left ignition, the engine essentially died ((at about 46:30). It looks for the 2 seconds that we were on just the left ignition, the EGTs on #1 and #2 plummeted. The behavior did not change even after enriching the mixture. Also, after landing, I was able to reproduce it (engine running very badly on just the left ignition) even at idle RPM.

The evidence seemed to point to the coil on the left ignition that supplied #1 and #2 cylinders. I worked with my A&P to figure out the coil to plug to ignition mapping and figured out what appeared to be the problem coil. I happened to have a spare coil which came when I bought the plane so I went ahead and replaced the problem coil (let's call it L1 since it was the first coil on the left ignition).

I did a test flight on 8/10 and I wasn't able to reproduce the problem so I thought I had fixed it.

Then, on a flight with 2 passengers last Sunday (8/18), as I was leaning the mixture for cruise (with both ignitions on), I noticed that the some of the EGTs had increased above 1400 and were not coming down (they started going up even when I was quite a bit ROP). I decided to do a precautionary landing enroute at Byron (C83) and when I did an ignition test on the ground (at about 54:40 in the 2nd image), I had the same issue where the engine ran very badly on just the left ignition and looking at the chart, it again shows the EGTs on #1 and #2 plummeted when the right ignition was turned off. I repeated it at 55:24.

I went ahead and replaced the L1 ignition coil with the one that was in the plane originally and when I started the engine and did an ignition test, the same issue kept happening. It was a hot day and I had some suspicion that it may be heat related so at that point, I parked the plane in a maintenance hangar and went out for lunch with a helpful local pilot. When I started the engine around 1-1.5 hours later, the problem did not show up on the ground during a high RPM run-up so I headed back to home base (KRHV - about a 20 min flight) and had an uneventful flight.

I have been exchanging emails with Klaus and also spoke with him. Given my (low level of) knowledge and his expectations, it has been a bit challenging!

A few questions:
- Could this sequence of events (the EGT behavior and the badly running engine on one ignition) point to any other possible issue (other than the ignition)? I have separately been chasing a different issue where it looks like my A&P's uninformed lackey took the Airflow Performance restrictors out to be cleaned at the time of the CI in March and then put them back in randomly. So, I have been going through the GAMI sweeps and changing the restrictor locations to get a better spread.

-Any suggestions on what may cause this kind of intermittent ignition issue (which may possibly be related to heat)?

-Am I possibly chasing more than one ignition related issue?

Here are my next planned steps:
-I worked with my A&P to figure out the ignition coil to spark plug mapping but I am now not 100% sure we got it right so we are going to repeat that tomorrow using a induction timing gun (to know exactly which plugs/coils are on which ignition circuit).
-If it turns out that I previously got that wrong, then perhaps I have replaced the wrong coil in the past so I will replace the appropriate coil (which fires #1 & #2 on the left ignition)
-if it turns out that the previous mapping I had was correct (and I was dealing with the correct coil), my plan is to swap that coil with the next coil over (which is a known good coil/channel on #3 & #4) to see if the problem moves to #3/#4 or if it stays with #1 and #2 in which case it may point to the channel on the LSE Plasma controller being the issue.

One other suggestion I had was to ensure that the spider is distributing fuel ok so I guess I am planning to do the "cup test".

Any other insights or suggestions are welcome!

Thanks,

Vas

 

[Carl Froehlich]

Here is a good video on Lightspeed stuff. It shows you how to check for a bad coil.

Note the spark plug wire replacement requirement. I found Lightspeed ignitions to be very sensitive to plug wires.

On your A&P screwing up the nozzles, I would have been pissed. At any rate I would be surprised if the builder did not log what size nozzle was in each cylinder. Check the logs and see. The nozzels (other than the stock 0.028”) should all be stamped on the size. I had a GAMI spread of 1.5GPH on the stock nozzles. I replaced four (all going smaller) and the gami spread when to essentially 0GPH.

Verify the coils, plug leads and plugs good. Fix your GAMI spread problem and let us know.

Side note. Whatever you are using for the backup power for the ignitions, verify it works. I’ve found more than one “per Klaus’ install manual” setup with an absolutely flat backup battery.

Carl
New RV-10 with dual pMags

 

[Avanza]

According to the Installation Manual, Coil reliability.
The following installation issues and operating conditions can cause these coils to fail prematurely.
- Excessive output resistance:If one of your spark plug wires is not installed all the way and it vibrates off of the coil or the spark plug, the resistance goes to infinity and the
coil will eventually breakdown internally.
- Maximum continuous operating temperature is 160 F.
- Increased spark plug resistance: The Denso plugs supplied with your system have a high quality 5k resistor built in. Lower quality plugs can burn out their resistor causing the coil to fail. Use only Denso spark plugs for best performance and reliability.
- Worn spark plug gaps: The longer spark required to jump a bigger gap requires a higher voltage. For this reason it is important to maintain the plug gap. Precious metal spark plug electrodes do not wear as fast as nickel electrodes. The spark plugs should be replaced or re-gapped at 100-hour inspection intervals.

Ignition, fuel and air is essential for engine operation.
If it were my aircraft and flying with friends, I would seriously look for a different electronic ignition system.

Good luck

 

[vas4vans]

Here is a good video on Lightspeed stuff. It shows you how to check for a bad coil.

Note the spark plug wire replacement requirement. I found Lightspeed ignitions to be very sensitive to plug wires.

On your A&P screwing up the nozzles, I would have been pissed. At any rate I would be surprised if the builder did not log what size nozzle was in each cylinder. Check the logs and see. The nozzels (other than the stock 0.028”) should all be stamped on the size. I had a GAMI spread of 1.5GPH on the stock nozzles. I replaced four (all going smaller) and the gami spread when to essentially 0GPH.

Verify the coils, plug leads and plugs good. Fix your GAMI spread problem and let us know.

Side note. Whatever you are using for the backup power for the ignitions, verify it works. I’ve found more than one “per Klaus’ install manual” setup with an absolutely flat backup battery.

Carl
New RV-10 with dual pMags

Thanks, Carl!

I did see the videos on Lightspeed from Vic. I do have the old style ignition coils and it looks like putting in a new style coil (given the different form factor) is a non-trivial exercise. The local RV expert A&P in the area is Lee Apaka out of Rio Vista. I spoke with him - he definitely seems to know Lightspeed (unlike my local A&P) and his suggestion was that in addition to the wires, I should look at replacing all the coils with the new style coils.

I checked the resistance on the ignition wires and they are all less than 160 ohms. That having been said, they are coming up on 500 hours so part of what I plan to do tomorrow is to measure all the wires and order new ones from Klaus. I have ordered new spark plugs (I do use the recommended Denso IK27) so even though it has been less than 100 tach hours since they were replaced, I will just go ahead and replace all the plugs. Also, I checked the resistance of all the coils and they are all between 8000 and 8500 ohms.

Yeah, the nozzle screw-up was really unfortunate. Part of it was I didn't really know myself how the "tuning" was done. There was no information on the cylinder to nozzle size mapping in the engine logs. I reached out to the previous owner and Don at Airflow Performance and unfortunately, neither of them had any records (any more) either (this was from ~2016-2017). As you pointed out, the nozzles are all stamped and their locations/sizes matched what I was seeing on the timing of the EGT peaks so I did one round of swaps and found that the GAMI spread had improved quite a bit (from 1.7 to 0.7 gph). I did one more swap and was trying to do another GAMI sweep on Sunday (to confirm nozzle placement) when the ignition related issue happened and became a higher priority!

According to the Installation Manual, Coil reliability.
The following installation issues and operating conditions can cause these coils to fail prematurely.
- Excessive output resistance:If one of your spark plug wires is not installed all the way and it vibrates off of the coil or the spark plug, the resistance goes to infinity and the
coil will eventually breakdown internally.
- Maximum continuous operating temperature is 160 F.
- Increased spark plug resistance: The Denso plugs supplied with your system have a high quality 5k resistor built in. Lower quality plugs can burn out their resistor causing the coil to fail. Use only Denso spark plugs for best performance and reliability.
- Worn spark plug gaps: The longer spark required to jump a bigger gap requires a higher voltage. For this reason it is important to maintain the plug gap. Precious metal spark plug electrodes do not wear as fast as nickel electrodes. The spark plugs should be replaced or re-gapped at 100-hour inspection intervals.

Ignition, fuel and air is essential for engine operation.
If it were my aircraft and flying with friends, I would seriously look for a different electronic ignition system.

Good luck

Thanks! On your last point, I can't say I haven't been thinking about it! I am planning to finish up current troubleshooting. If it turns out to be the plugs, ignition wires or a coil, then I'll likely just stick with Lightspeed for now. If it turns out that I need to replace all the coils or one or both Plasma CDI units, then I may seriously start thinking about alternatives.

Thanks,

Vas

 

[Full Throttle]

Thanks, Carl!

I did see the videos on Lightspeed from Vic. I do have the old style ignition coils and it looks like putting in a new style coil (given the different form factor) is a non-trivial exercise. The local RV expert A&P in the area is Lee Apaka out of Rio Vista. I spoke with him - he definitely seems to know Lightspeed (unlike my local A&P) and his suggestion was that in addition to the wires, I should look at replacing all the coils with the new style coils.

I checked the resistance on the ignition wires and they are all less than 160 ohms. That having been said, they are coming up on 500 hours so part of what I plan to do tomorrow is to measure all the wires and order new ones from Klaus. I have ordered new spark plugs (I do use the recommended Denso IK27) so even though it has been less than 100 tach hours since they were replaced, I will just go ahead and replace all the plugs. Also, I checked the resistance of all the coils and they are all between 8000 and 8500 ohms.

Yeah, the nozzle screw-up was really unfortunate. Part of it was I didn't really know myself how the "tuning" was done. There was no information on the cylinder to nozzle size mapping in the engine logs. I reached out to the previous owner and Don at Airflow Performance and unfortunately, neither of them had any records (any more) either (this was from ~2016-2017). As you pointed out, the nozzles are all stamped and their locations/sizes matched what I was seeing on the timing of the EGT peaks so I did one round of swaps and found that the GAMI spread had improved quite a bit (from 1.7 to 0.7 gph). I did one more swap and was trying to do another GAMI sweep on Sunday (to confirm nozzle placement) when the ignition related issue happened and became a higher priority!



Thanks! On your last point, I can't say I haven't been thinking about it! I am planning to finish up current troubleshooting. If it turns out to be the plugs, ignition wires or a coil, then I'll likely just stick with Lightspeed for now. If it turns out that I need to replace all the coils or one or both Plasma CDI units, then I may seriously start thinking about alternatives.

Thanks,

Vas

Vas.
If your ever down in the Los Angeles area, let me know and I'll show you how the Aerosparks Ignition works. I think you'll like it.

 

[DanH]

Make sure the fast-on terminals have a tight fit on the coil spades. I mean really tight. Any discoloration is a telltale.

This one from the way-back file; be sure your installation uses RG400 between the box and the coils, not RG-58 as was once common. The RG-58 center conductor can migrate through the insulation given enough heat. Totally unsuited for engine compartment use.

Absolutely make sure your mechanic does the MAP sensor conformation test as the last item before it goes back in service. Disconnect the vacuum line between the source cylinder and the MAP sensor terminal on the box. Plug the end leading to the cylinder. Mark the back of the flywheel at 25 BTDC using WhiteOut, paint, or another high visibility material. Run the engine and use a timing light to confirm the timing is at 25 BTDC (marked line on the flywheel aligned with the case split). If it's advanced to some higher value, the MAP sensor is bad, which means the ignition is firing at that excessive advance all the time.