Lightspeed Ignition Misfire

RVadmirer · #1 01-28-2007, 06:57 PM

I just came from the hangar where I had to cancel a flight when at run-up the Lightspeed ignition missed really bad.

It only has about 40 hours on it and has never been a problem except when a plug lead fell off and I found the installer had left 3 of 4 loose!

Not so lucky (?) this time. All were tight and the plugs don't look bad. I've searched the archives and saw one set of posts commenting on the other electrical connectors and will check those next. Any other ideas?
Thanks!

dan · #2 01-28-2007, 08:02 PM

What type of crank position sensor do you have? Hall effect sensor in the mag hole, or flywheel magnets?

Things to rule out:
- spark plug wires hooked up correctly
- spark not "shorting" i.e. plug wires chafed on a baffle or something like that
- connectors at the coils on solid (check the wires & strain relief)
- phase test the coils (see the Lightspeed manual)
- crank position sensor wiring not damaged, connected properly at both ends
- voltage ok?

If all of this checks out, then it likely points to the crank position sensor. If you have one with flywheel magnets, the clearance between the sensor and magnets is specific.

If in doubt, call Klaus at Lightspeed. He has helped me out in the past when I thought I had a problem with my Plasma II.

Captain Avgas · #3 01-31-2007, 01:10 AM

Quote:

Originally Posted by RVadmirer

I just came from the hangar where I had to cancel a flight when at run-up the Lightspeed ignition missed really bad.

It only has about 40 hours on it and has never been a problem except when a plug lead fell off and I found the installer had left 3 of 4 loose!

Not so lucky (?) this time. All were tight and the plugs don't look bad. I've searched the archives and saw one set of posts commenting on the other electrical connectors and will check those next. Any other ideas?
Thanks!

So in the end...what was the problem.

dreamweaver · #4 01-31-2007, 07:57 AM

For what its worth,I work at united airlines in the engine test cell and spend alot of time with elec problems. My buddy built a chtistian eagle with dual light speeds.With only about 6 hours on the aircraft it started to miss once in a while. Every body was talking about valve problems but what I found after reading about it was that they had the wires for the hall effect pickups tied up with the RH lower spark plug wires. I also found a very small burn on one wire from the exhaust. Both were fixed at the same time and its been flawless sence then. I'll say one thing about that ignition is that it sure makes starting easier. I'm building an rv-8 and plan on using it

RVadmirer · #5 01-31-2007, 09:20 AM

Have been talking to Klaus. The wires he specifies to be kept 3" apart were run together through the firewall. And when I first got the plane back from the shop where the ignition was installed a plug wire had fallen off at run-up. Klaus says this is very bad for the coil. We are still troubleshooting. Will post the results when solved.

Yukon · #6 01-31-2007, 09:44 AM

A pair of Slicks will solve that problem! Cheap, redundant and self-generating.

LifeofReiley · #7 04-19-2009, 07:13 PM

Quote:

Originally Posted by RVadmirer

Have been talking to Klaus. The wires he specifies to be kept 3" apart were run together through the firewall. And when I first got the plane back from the shop where the ignition was installed a plug wire had fallen off at run-up. Klaus says this is very bad for the coil. We are still troubleshooting. Will post the results when solved.

Anybody using safety wire or some other method to secure EI spark plug leads on the sprark plugs? I also had #3 lead come off Saturday... well it was detected on run-up during the mag off check. No earlier symptoms or signs of a problem was noted in the previous flight. Okay, back to the hangar, pull the cowl and plenum top just to find a #3 wire no longer snapped securely on the spark plug. Any Suggestions?

dan · #8 04-19-2009, 07:25 PM

Quote:

Originally Posted by LifeofReiley

Anybody using safety wire or some other method to secure EI spark plug leads on the sprark plugs? I also had #3 lead come off Saturday... well it was detected on run-up dring the mag off check. No earlier symptoms or signs of a problem was noted in the previous flight. Okay, back to the hangar, pull the cowl and plenum top just to find a #3 wire no longer snapped securely on the spark plug. Any Suggestions?

Secure the wires mid-run. They're probably wigglin' around in there.

FWIW, I use 4 of the plastic 2-wire guides (Klaus provides them), each secured to something. There is no "slack" in the wires whatsoever. No chance for them to move.

I recently had a problem with one of my coil terminals after 1800 hours, and it was directly due to one of the wire guides coming loose and working the terminal. You (the collective you -- we) really have to focus on getting those wires immobilized imho.

Forgot to mention...I ended up going with custom-length wires that I cut to fit exactly, with no extra/slack. The ones Klaus provided originally would have "worked" but weren't an exact fit. Less wire = less resistance + less chance of floppin' in the breeze. FWIW, I bought the MSD cut/crimp tool and some bulk MSD 8.5mm wire and 90* terminals (Klaus sells all of that, but I think I bought my MSD tool from Summit).

LifeofReiley · #9 04-19-2009, 07:38 PM

Quote:

Originally Posted by dan

Secure the wires mid-run. They're probably wigglin' around in there.

FWIW, I use 4 of the plastic 2-wire guides (Klaus provides them), each secured to something. There is no "slack" in the wires whatsoever. No chance for them to move.

I recently had a problem with one of my coil terminals after 1800 hours, and it was directly due to one of the wire guides coming loose and working the terminal. You (the collective you -- we) really have to focus on getting those wires immobilized imho.

Forgot to mention...I ended up going with custom-length wires that I cut to fit exactly, with no extra/slack. The ones Klaus provided originally would have "worked" but weren't an exact fit. Less wire = less resistance + less chance of floppin' in the breeze. FWIW, I bought the MSD cut/crimp tool and some bulk MSD 8.5mm wire and 90* terminals (Klaus sells all of that, but I think I bought my MSD tool from Summit).

Hi Dan,

I have these black holders that the wires clip into. It has a center hole and I have the holders adel clamped to a push rod tube. The wires as delivered are a little long. I will make sure they're pulled tighter on the plug end at the next oil change. (5 more hours)

Thanks Dan!

AlexPeterson · #10 04-19-2009, 07:55 PM

A trick that might help keep this type of plug boot on is to push them on until one can feel the metal portion inside engage the plug. Then, while rotating slightly back and forth, advance the boot (the end towards the plug) a little more. Without doing this, it is easy to build some compression in the boot, which tries to push the connector away from the plug. Preferable is to have some tension in the boot, holding the connector onto the plug.