Peter, I once had a vehicle with a conventional points ignition system and
the same problems. The answer was exactly as Electroair is telling you. The
vehicle was an early Ford Econoline Van, the kind with the engine in a metal
doghouse between the driver and passenger seats. I left the cover off one
night to try and diagnose the misfiring by ear and sorted it out by eye
instead. Most amazing light show I've ever seen so close up. New plug wires
with a high temperature rated silicone insulation did the trick. If you're
running car plugs for the EIS system I'd make new plug wires, as A: it's the
quickest to eliminate on the list of probables, B: Costs little as airplane
parts go, C: If the condition doesn't change you're in a better position to
ask for more help from Electroair, and D: If it does work you're flyin'
again.
Rick
On Mon, Oct 6, 2008 at 4:20 PM, Peter Pengilly <peter@sportingaero.com>wrote:
> peter@sportingaero.com>
>
> Hi All, I'm posting this for a friend who is not a member and is trying
> to diagnose an electronic ignition problem. Any thoughts would be
> gratefully received.
>
> I have an interesting problem with my electronic ignition that I'd
> appreciate further opinion on. My RV6 has an O-320 with a Slick magneto
> on the left drive and Electroair EIS on the right drive. The EIS is a
> dual coil, lost spark system (each coil fires 2 opposing cylinders on
> both compression and exhaust stroke), and has been successfully operated
> for 480 hours.
>
> The problem is that each time I go to take off the engine misfires when
> full power is applied. I am getting 2150 rpm static, and as the plane
> accelerates at full power, after 10-15 seconds the engine starts to
> misfire. The misfires occur at roughly 1-2 seconds frequency and last
> for 200-700 milliseconds. There is never any backfiring.
>
> I've conducted one flight, and found that as soon as I eased the climb
> and reduced power, the problem went away. I was able to fly at 2,600 rpm
> with no problems, and could not re-create the misfire whilst airborne.
> Because there is no backfiring, I initially assumed a problem with fuel
> supply. This has been eliminated, and I have been testing the ignition
> system whilst static on the ground.
>
> I connected an oscilloscope input to an ignition lead and the trace gave
> large spikes at every 1/2 engine revolution as expected. However,
> intermediate lower amplitude spikes were also observed at 2/3 to 3/4 of
> the main spike period. This occurs throughout the full rev range,
> including clean running.
>
> I also tested the signal output from the magneto timing housing. It was
> found to have irregular modulation and an irregular gap.
>
> I don't know what signal the processor unit can tolerate, but I think
> that the irregular signal from the timing sensor may be the issue.
> However, the manufacturer still suggests that the charge is arcing out
> through either the leads or plugs.
>
> Having replaced both the leads and plugs, and that there's no evidence
> or arcing through either the power or earth connections, I think it's a
> fault with the unit.
>
> One significant point is that when I turn off the EIS, the engine runs
> perfectly on the single magneto. When the EIS is turned back on and the
> misfire occurs, I would expect the magneto to continue firing as normal.
> I think it probably is, but there's no fuel left to burn and the
> misfiring is caused by wrongly timed sparks from the EIS igniting fuel
> in the cylinders before the mixture is compressed and ignited by the
> magneto.
>
> Am I missing something? Any thoughts would be much appreciated
>
> Regards, James
> RV6 G-JSRV
>
>
