Lightspeed run up issue

Last two flights I did a runup and found the Lightspeed was either out of time, or just missing very badly. Pulling and resetting the breaker cured it instantly, both times. Inflight has had no issues for 300 hours.
At about 50 hour intervals I clean the pins on the sub D that connects to the Hall Sensor...
Anyone seen this odd behavior before in their installation?

flightlogic said:

Last two flights I did a runup and found the Lightspeed was either out of time, or just missing very badly. Pulling and resetting the breaker cured it instantly, both times. Inflight has had no issues for 300 hours.
At about 50 hour intervals I clean the pins on the sub D that connects to the Hall Sensor...
Anyone seen this odd behavior before in their installation?

Click to expand...

Check the resistance through the breaker....... bad contacts?

I wonder if the resistance reading would be valid in circuit?
Maybe I should just disconnect the leads to the breaker first.
I just hate crawling in under the panel. Last time I got stuck and then dropped my cell phone out of reach. Thought I might be there until I starved to death.
The rescue, unfortunately is neither on you tube nor social media. What a shame.

flightlogic said:

Last two flights I did a runup and found the Lightspeed was either out of time, or just missing very badly. Pulling and resetting the breaker cured it instantly, both times.

Click to expand...

When I have had misses with these, it was either improperly set-up trigger spacing, or corrosion (from water) in one of the coil output terminals. Once I had a coil go bad and in the P-III, a defect in the box. In the latter case, the problem was a poorly supported chip that broke a connection. It is a problem with some of the P-IIIs but not mentioned on Klaus's website.

I don't see how pulling the CB is any different from turning the switch off and I don't know why interrupting power would reset anything. I tend to think your miss is not related to power supply.

Oh yeah, runup misses can be due to carbon fouling. See if leaning clears the miss. If plugs are lead-fouled, they won't clear with leaning.

Both times my LS Plasma III gave me trouble in the last 1100 hours, it was a failure of the circuit board on the Hall effect sensor.

Jerry Esquenazi
RV-8 N84JE

light speed has updated their spark plug recommendations

http://www.lightspeedengineering.com/Products/Sparkplugs.htm

I have the flywheel pickups instead of the hall effect units.

The only problem I've had in 1,300+ hours is a lousy crimp (**** builder) on one of the coil connectors...

flightlogic said:

Last two flights I did a runup and found the Lightspeed was either out of time, or just missing very badly. Pulling and resetting the breaker cured it instantly, both times. Inflight has had no issues for 300 hours.
At about 50 hour intervals I clean the pins on the sub D that connects to the Hall Sensor...
Anyone seen this odd behavior before in their installation?

Click to expand...

The short answer - yes.

You options are to start swapping out coils, plugs and wires, then end up sending the box in to Klaus for an expensive repair.

Good luck,
Carl
Former Lightspeed owner - now 600 hours with pMags.

Carl Froehlich said:

The short answer - yes.

You options are to start swapping out coils, plugs and wires, then end up sending the box in to Klaus for an expensive repair.

Good luck,
Carl
Former Lightspeed owner - now 600 hours with pMags.

Click to expand...

I got so frustrated after my last box failure (Klaus said there was nothing wrong with it but swapping it with another box fixed it) that I removed both LSI's and installed a Pmag and an Electroair, never looked back.

Bottom line though is I kept the good unit for a spare, you're welcome to borrow it for troubleshooting if you need it.

Same here, sent back my box after I was down for weeks. Said nothing was wrong. Worked fine........

Last time it failed said he was headed to Europe and would look at it when he got back. Bought a pmag the next week, had it repaired months later when he got around to it and sold it immediately. Done with that nonsense.

The fact that a power reset solves the problem points to the software. Something is getting out of sorts (bad data in a table/array somewhere) and the cycling of power forces everything back to startup/default mode. This could point to any number for problems with the circuit board(s), but could also be related to issues such as grounding or intermittant shorts in the sensor/input feeds. My first guess would be a bad solder joint on the board. The vibration of an airplane is a tough environment for electronic boards. It could also point to problems with your hall / VR sensor (not sure what your system uses). If the pulses are not clear to the logic controller, the unit can become confused. However, I would expect much more severe problems not just a limited timing drift.

Larry

options

Walt,
Might take you up on the loaner test box.
The prevailing sentiment seems to be that another P mag is in my future though.....