Electroair Electronic Ignition on a Fuel Injected Comanche

[Northtownmike]

Hi All,

I have an electroair electronic ignition setup paired with a mag on a my Comanche 250 (converted to fuel injection). The system works well below 80% power but at WOT/takeoff/manifold pressure at or greater than 25 inches, the engine stutters and makes a scratching noise. You can feel and hear the noise and it is most prominent on takeoff. It is intermittent and random but only under high power. There is certainly a reduction in performance although not drastic.

When operating only on the electron ignition system there are no issues or while only on the mag. If you run very LOP the issues goes away as well. The mechanics are stumped and electroair believes it is not their system causing this. We had the representative of their company evaluate the equipment and replace the main parts w/o resolution.

My theory is the mag and electronic ignition are fighting each other. Maybe there is an uneven fuel burn (in the cylinders/or between cylinders?). We tried changing the plugs w/ no avail as well.

I do know all the other systems that had the electronic ignition system installed that worked well had GAMI injectors. Could the upgrade improve this?

Anyone have any experience with this system or similar issues? Any advice is helpful. Thanks in advance.

 

[N1120A]

Think it might be resetting? SureFly had a problem with this in 28v applications until they came out with a fix.

 

[Magman]

Odd noise, vibration and power loss at high power could well be detonation.

Generally ; mixture should be slightly richer than Best Power.

Could you be too lean?

I’ve seen engines where applying Carb Heat richens the mixture and results in

higher Static RPM.

That won’t work here.

Other diagnostic techniques?

 

[LSK]

I saw a guy post on FB this morning with same issue - however, the guy on FB had taken a perfectly reliable carb engine and thrown money at it converting to fuel injection and an electronic ignition - I doubt his engine will ever be as reliable again as it originally was - in your case can you put the mag back on it and make sure its timed correctly and see if the problem persists ?

 

[kyleb]

I have flown electronic ignition on my RV for 20 years. Yours sounds like a timing problem where at full power you're getting into detonation or something like that. Ignition events don't "fight" each other.

I haven't looked at current electroair documents, but it is easy to make dumb timing mistakes when you have a mag that is timed according to one procedure and an EI with timing set by another procedure.

 

[Northtownmike]

Odd noise, vibration and power loss at high power could well be detonation.

Generally ; mixture should be slightly richer than Best Power.

Could you be too lean?

I’ve seen engines where applying Carb Heat richens the mixture and results in

higher Static RPM.

That won’t work here.

Other diagnostic techniques?

It actually runs better very LOP. The issue goes away.

 

[Northtownmike]

I have flown electronic ignition on my RV for 20 years. Yours sounds like a timing problem where at full power you're getting into detonation or something like that. Ignition events don't "fight" each other.

I haven't looked at current electroair documents, but it is easy to make dumb timing mistakes when you have a mag that is timed according to one procedure and an EI with timing set by another procedure.

I had the mechanics triple check the timing. No resolve.