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Electronic Ignition problem - any suggestions?

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peter(at)sportingaero.com
Guest

Posted: Mon Oct 06, 2008 1:22 pm Post subject: Electronic Ignition problem - any suggestions?

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

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jindoguy(at)gmail.com
Guest

Posted: Mon Oct 06, 2008 2:22 pm Post subject: Electronic Ignition problem - any suggestions?

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(at)sportingaero.com (peter(at)sportingaero.com)> wrote:

[quote] --> AeroElectric-List message posted by: "Peter Pengilly" <peter(at)sportingaero.com (peter(at)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

 

 

 

 

 

 [b]

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klehman(at)albedo.net
Guest

Posted: Mon Oct 06, 2008 3:20 pm Post subject: Electronic Ignition problem - any suggestions?

I wouldn't waste any time thinking about this until first replacing the 

spark plugs (seriously) and then the wires but apparently that has been 

done. I've also seen failing ignition coils do what you describe. 

Electroair coils look like GM automotive coils which would mean they may 

be cheap to replace??



A multi tooth pickup wheel will have a repeating irregular pulse pattern 

AND the pulse voltage will vary accordingly. All teeth are not evenly 

spaced or there is at least one tooth missing to establish timing. I 

don't know how reliable the Electroair pickup has been but it would not 

be my first suspect.



A scope will show an amazing amount of noise on both primary and 

secondary sides of these coils. As long as it is a regular repeating 

pattern, it is probably normal. Yes they are of similar voltage to what 

fires the plugs. I'd only be suspicious if they are non repeating spikes.



Ken



Peter Pengilly wrote:

 	  Quote: 	
		   

 

 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

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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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