Dual Electroair Ignitions Poor Idle - SOLVED
 

Hey folks,

I have a freshly rebuilt IO-360-C1C (Angle Valve) that I'm running dual Electroair EIs on (the newest model). I've been having trouble getting it to idle below about 1000rpm without misfiring and stumbling. At first I thought maybe it was due to the idle mixture not being set correctly (the fuel injection system is also freshly rebuilt), but setting it richer or leaner still will not let it idle below 1k. I checked for induction leaks and did find a bit of an air leak at one of my intake tube gaskets, so I replaced that and confirmed no more leaks. Still no better at idle though. I verified the mag timing sensors were set correctly with the alignment pins dropping right in as #1 was at TDC. I verified that the actual timing matched what the controllers were reporting, both indicating 35deg BTDC at ~1100RPM and 13" MAP. On a hunch I disconnected the MAP sensors forcing the timing to go to 25deg, and low and behold she idle smooth as silk all the way down to 550rpm. I've confirmed the compression is good, all were 78-79/80.

Electroair tells me it should idle fine at 35deg advance, but I'm not sure what could be causing mine to misfire so bad. If anyone here as any thoughts or experience with this I'd be incredibly grateful.

-John Basol
Cozy MKIV - Barely into Phase 1 testing.

There's no reason for it to advance at idle. The timing curve should only start to advance once the engine reaches a higher RPM.

Actually after thinking about this a bit, I recall that in my -6 my Electroair did run the advance up at idle, and it was 35-40 degrees. An intake tube leak will cause it not to idle below 1000 rpm.

I had a similar problem on an older style Electroair ... Turned out to be a vacuum leak at the manifold pressure sensor connection.

I am running an angle valve IO 360 in my RV6 with two E-mags and I had the same/similar problem, on first start engine would run fine but after a flight while on the taxi back my engine started missing and running rough I could not get the rpm under 900.
I looked at mixture then mags, Then figured I was having fuel vaporization problems, My fuel line from the fuel control to the distributor valve ran up to the top of the engine between two cylinders. I have wrapped fiberglass heat shield with aluminum backing around the fire sleeve and sealed with aluminum tape. Cured all the missing and rough running and rpm comes back to 700 smoothly now.

I am not saying this will fix your problem but could well be worth a look as I find the heat off the cylinders really heats up my top cowl a couple of minutes after shut down.
Good luck

Timing is everything!
 

Hi John,

I am on my third Electroair application, the first 2 were the old style. I never had the problem you discuss but one sure fire way to troubleshoot an intake leak is with a simple can of WD-40. First de-cowl and chock/anchor nose(Cozy)/tie down tail(most RVs).

1. Start it up, pull it back to the lowest idle it can maintain.
2. Carefully walk down trailing (Cozy) leading edge(RV) to front/rear end, crouch down with WD40 in hand.
3. With straw spray attachment on, carefully spray a stream at base of intake tubes and around your MP fitting for the E.I.
4. If RPM increases at all, you have an intake leak.

If the WD40 trick reveals no leaks, try different plugs and disconnecting one E.I. vacuum advance individually. Also experiment with switching one or the other off at idle. This should help narrow down the culprit.

Email me offline if none of this works...

SeeYa!

Smokey
smokyray@rocketmail.com

PS: Love that Cozy!

Carburetor cleaner also works well for the "intake leak test" :cool:

Thanks for all replies folks! I should problably provide a bit more info. First, induction leaks. I did a pretty thorough check of induction leaks, which is how I found the leaking gasket on the #2 intake runner. I didn't use any chemicals as I would in a car or normal airplane though, as the pusher config of the Cozy doesn't let you get very close to the engine while its running and still feel like you're safe. What I did was disconnect the map sensor line at the manifold and cap it off. Then I took out the injectors and replaced them with brass blugs. Next I removed the aircleaner and replaced it with a cap that had an air compressor fitting on it. I pressureized the whole intake track to 14psi (about 60" MAP) and sure enough had a leak at that one gasket. I replaced the gasket and made sure that the flange seated correctly as I reattached the pipe. After retesting I had zero leaks at 14psi, only air that could be hear was faintly through the crank case breather or one of the exhaust tubes (changed depending on which cylinder had the exhaust valve open).

The fuel line from the servo to the distribution spider is routed around the accessory case side of the motor, so I've minimized it's exposer to heat as much as possible. I won't rule it out yet, but this poor idle is apparent right after start up as well, which makes me think it's not heat related. I could certainly be wrong.

I'll throw another wierd piece of info into the loop. I was reviewing my datalogs (GRT EIS) from when I did the initial break in on a test cell at the engine shop. I remembered it idled fine at that time. Sure enough my logs show it was also running 35deg advance at that time. I can't remember exactly when I first noticed this trouble, but I confirmed that during my first (and so far only flight) the ignition was running 35deg as well. Obviously something had to have changed. I just can't figure out what.

Thanks again!

-John

P.S. for anyone curious about us crazy Rear wheel drive guys.... :) http://cozy.basol.net

Is it running at 35degres BTDC at idle?

should be around 35 at full power and 5-15 at idle on a electronic system with a programmed ignition curve

That is correct. With the MAP sensors connected it's running 35deg BTDC at idle.

I'm going to check the MAP sensor lines for leaks this evening, as I had disconnected those when checking the induction track for leaks (didn't want to send 2bar pressure at MAP sensors not designed for more than 1bar).

-John