Dual Electroair Ignitions Poor Idle

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
[email protected]

PS: Love that Cozy!

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

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

With the manifold pressure disconnected I would "assume" the timing should go to 25 deg (this would be equivelent to full throttle).

I had a similar problem with 2 mags.

The symptoms were very poor idle and even a quit sometimes at less than 1000 rpm.

The cause was the FI system. Fuel flow would not drop below 2 gph at idle. The FI system has an idle feature that should drop to about 1 gph. It was not doing that. Don at AFP fixed it.

If you have fuel flow indication, check it at idle.

Depends on the generation ElectroAir. I have the older system but with a mag housing pickup. It idles around 15-18 degrees and it only advances above 25 BTDC at high altitude and low RPM. I would expect a rough idle at 15-18 BTDC timing.

That's correct, with the sensors disconnected it fixes the timing at 25deg. Electroair does not set up any RPM based advance. They set a fixed timing of 25deg and then advance the timing based on manifold pressure. To me this seems like they're missing part of the equation to optimum ignition timing, but I found it didn't pay to argue the point with them, they only tell me: "we have thousands of these out there that don't exhibit this behavior".

The engine idles sooooo smooth at 25deg, I'm inclined to change the timing curve to idle it there. But I saw Klaus runs 35deg at idle with the Lightspeed as well, so it gave me pause to contemplate why my engine doesn't seem to like that.

-John

Isn't the whole point of electronic ignition to advance the timing at high speed/high power settings? I can't seem to wrap my head around advancing the timing to 35deg BTDC at idle. Isn't that backwards?

The E-mag installation documentation (I realize we're talking Electroair here) has a graphical representation of the advance curve, and they use 20-25 deg at idle and up to 39deg at high RPM.

Exactly! In every auto engine I've ever dealt with, Idle is around 15-18deg BTDC, and it advances as rpm increases.

I doubt there is much to be gained from such an advance at Idle, so I won't be terribly worried if I have to make some changes to what Electroair has for a curve, but I'm still perplexed on why it worked at one point, but now doesn't.

-John

Dennis_I said:

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

Click to expand...

This is incorrect. At full power timing is 25 degrees, and this is not unique to the electroair.

It is possible for an air leak to show up under vacuum that would not show up under pressure.

Just a thought.

just an example of a "normal" timing curve...

I think electronic ignition confuses too many people.

In a perfect world the EI will have the same timing as the mag at idle (25 BTDC on most of our engines), it would have the same timing as the mag at full power (25 BTDC on most of our engines) BUT it would advance once the engine is under lighter loads such as economy cruise at altitude (6K and above).

Linking the timing to RPM alone is asking for the engine to give up. Linking the timing to just the MAP is also not good. The 2 have to work together.

Surely most of you guys have seen the inside of a pre-electronic ignition distributor in a car/truck? It has a vacuum (MAP) hook-up and weights on springs that work together to advance the timing when the car is cruising down the road. Read, engine under light load.

The same principals apply to the EI in our airplanes. Some vendors go a step above and change the baseline curve for different situations but it all goes back to advance the timing ONLY when the engine is under a light load.

Well, it took a bit of troubleshooting with the ignitions we have it solved.

I had one mag timing housing that had a bad sensor. Not sure exactly what's wrong with it. The resistance was good on the pickup coil, so maybe one of the internal teeth was bad. I didn't open it, just sent it back.

With the new sensor the engine idles nicely, even with the 35-37 degrees advance. Now back to flying!

Thank you everyone for all your help!

-John