Starting Recommendations: 1 Impulse Mag +1 Pmag

We've recently acquired a 114-series P-Mag (with latest V40 firmware) with the intent of replacing the right hand Slick mag on our O-360-A1F6. The current plan is to retain the left hand impulse-coupled Slick mag.

My question to those with experience with this configuration is, should I continue to plan on starting using only the left impulse coupled mag, or should I simply set both P-lead switches to "ON" and start on both the impulse and P-mag? If experience has proven one method to work better than the other, why is that the case?

Our ignition control consists of toggle switches, so there's no worry about having to figure out how to make a key switch achieve the desired ignition configuration for engine start. P-Mag power is supplied through a separate toggle switch being fed from a separate breaker on the main electrical buss.

Thanks for your well-considered and helpful responses.

I have plasma iii on right, impulse on left. I can start off either, but it starts better on plasma.

My 2 cents

I was developing hard starting issues with two mags(especially with engine hot) and also installed one pmag. I always with both the slick mag and pmag on and never have had any issues with starting. I see no advantage of starting on one mag.

Like Alton, I have a slick mag and a plasma III. Similar to your installation I think. I start with both toggles on. No problems after 7 years, 600+ hours, and 600+ engine starts.

I've used the combo you are installing (slick-impulse and Pmag), it doesn't matter if you start on one or the other or both, on my plane any combo works just fine. But I used both all the time since there is no reason not to have all the spark you can get while cranking.
Tim Andres

Start on both.

Always use both, starts great

We have an impulse mag and one Pmag. Always leave them both on and she usually starts on first blade, we have a primer system but never use it.

Always have alternator on before start and until after shutdown also.

Thanks for the great feedback! From a point of logic I couldn't see any reason not to use both the impulse mag and P-Mag for starting and wanted to make sure there wasn't some obscure (or blindingly obvious! ) reason not to. Thanks to your very helpful replies I'll be using both ignition systems at engine start.

Personally, I ditched the impulse mag first on the two airplanes I've done. The Pmag renders the need for an impulse coupling obsolete, and you get to ditch the added weight and complexity of the impulse coupling. Win-win-win.

If you're in love with the impulse, start on both.

I have my left mag with impulse and right replaced with Electroair ignition. I decided to keep the impulse mag.
On a previous airplane, I had Plasma on the left and mag right without impulse. Had to start on the plasma in that case. The problem was if the battery was low the airplane could not be started as the battery voltage sagged to much to run the Plasma ignition. Not a problem at my home base, but when away a major inconvenience. So on my current airplane I kept the impulse, and if I can get the prop over compression with the starter, I can get it started.

With the impulse mag, I start on both.

I had been giving consideration to ditching the impulse mag entirely and installing the P-Mag on the left side. Given that we operate in cold weather, often where there is little-to-no aviation infrastructure, I opted to keep the impulse mag as an insurance policy. Getting started when out in the middle of nowhere on a cold day is critical.

Both. A recent experience: my battery had run down and wouldn't crank the engine. However, the P-Mag needs very little juice. I've read that a 9volt battery works. Hand-propping was the easiest I had ever encountered. One swing was it! I suspect the hotter spark from the P-Mag and I believe it fires multiple times on startup made it a breeze.

same question - good answers

It seems the more I read about EI the more confusing it can get.
tales of kick-back, stranding, etc. all seem to come from malfunctions, not normal ops.
The fear of starting with EI seemed to be that folks didn't trust the advance of the EI, and feared it would jump to 40 before the engine fired!
I too plan to keep the impulse mag as a backup, but expect starting on 'both' will be quicker with the long, hot spark of the EI.
( now if only those elves would get back to work and install it!)

flyboy1963 said:

It seems the more I read about EI the more confusing it can get.
tales of kick-back, stranding, etc. all seem to come from malfunctions, not normal ops.
The fear of starting with EI seemed to be that folks didn't trust the advance of the EI, and feared it would jump to 40 before the engine fired!
I too plan to keep the impulse mag as a backup, but expect starting on 'both' will be quicker with the long, hot spark of the EI.
( now if only those elves would get back to work and install it!)

Click to expand...

Perry - good points. In my original post you'll see I've made reference to having a 114-series P-Mag with V40 firmware. Like you, I had heard too many stories and witnessed a P-Mag losing its timing reference. V40 firmware gets us past most, if not all of these last little bugaboos with the P-Mags. At this point I think the P-Mag product has moved away from the "can't trust the advance" arena, or at least I sincerely hope that's the case.

Now I just have to get ME past the "forgot the master switch" and other such purely human failures. THAT's what's most likely to leave me stranded somewhere. Having an ignition system that doesn't require much juice (as beberle so clearly illustrated in his anecdote) is definitely a bonus. Having that, plus an impulse mag, puts me in a position of having to do something really stupid to result in being stranded. I think I'm just that stupid, so our aircraft's survival kit is well enough stocked to support an unexpected overnight stay in the bush!

You DO realize, don't you, Perry, that "airplane fixin' elves" are generally more motivated to show up and work if the airplane is in a heated hangar with a well-stocked beer fridge?!?!?

Thanks, everybody, for sharing your thoughts in this discussion. It's a wonderful thing to be able to benefit from the experiences of those who have blazed the trail ahead of you!

"forgot the master switch"

While you're installing the ignition, consider installing a low oil pressure warning light. In addition to it's primary function, it also functions as a "Master switch still on" warning after engine shutdown.
Cheers, David

koupster said:

While you're installing the ignition, consider installing a low oil pressure warning light. In addition to it's primary function, it also functions as a "Master switch still on" warning after engine shutdown.
Cheers, David

Click to expand...

Idiot lights are always a good suggestion. I have two of them, low volts and low oil pressure. That's like a belt and suspenders - how could anybody leave the master switch on with these two lights glaring from the panel?!?!

Oh, don't worry, I'll find a way...

Make sure your P-mag has version 40 on it!

If wired per E-mag's recommendation, if you start on the mag (P-mag powered but grounded) and you have version 39 or lower, there is a good chance your P-mag will lose it's TDC mark.

Another advantage of version 40 is that it fires at 4 degrees past TDC for easier starting. Older versions fire at TDC, which can cause kickbacks.

Here is the service bulletin from E-mag:
http://www.emagair.com/service-notes/

Also, make sure your P-mag is configured properly for your engine. Jumper in for a 25° engine or tuned with either our EICommander or Emag's EICAD program. Contact me offline, if you need details.

Thanks for chiming in, Bill. This is a 114-series P-Mag that's been back for E-MagAir's $85 flat rate check out service. At that time it was programmed with V40 and bears a handwritten sticker to that effect. I made sure of this before purchasing, thanks to having read some of your earlier (and very informative) posts on the topic.

This is a 25 degree engine so I'm planning to run with the jumper in place.

On my O-320, I went from two Slicks, to an E-Mag right and Slick w/impulse left, to two P-mags. I used both for starting, after the first change. Things I experienced (YMMV With one E-Mag, it started much easier and quicker, and I gained one gph lower fuel burn at cruise. With the two P-Mags, the idle was smoother, it would idle slower (nice on a fixed pitch 9A) and I gained 4 mph in cruise at 8000". I didn't notice any reduction in fuel burn with the second P-Mag. Love P-Mags!

Bob