Help! P-mags makes my engine run rough!

[Geico266]

I sent you a PM with the OSH phone number. I talked to the guys at the booth and they can help. Give them a call.

[jbDC9]

Another 2 cents...

My P-mags are both 113 series and of similar vintage, delivered early 2006 as I recall. I had numerous failures and "teething" troubles with mine as well; the last glitch I had at around the 200 hour mark sounds similar to your current problem.

I followed Brads suggestions and checked out my installation, wiring, plug leads and all that, but the problem remained. The final step of troubleshooting was swapping the units... lo and behold, the problem moved with the P-mag as Jim mentioned above. I sent it in and Brad mentioned that it indicated it had overtemped (I have blast tubes on the neck) but could find nothing else wrong with it. He replaced the circuit board and it's been running fine ever since... that was around 140 hours ago.

I will say that Brad and Tom are easy to work with and want to get these things running right... both of my units have had the circuit boards replaced, and both times the problems ceased. Perhaps the early units boards are a bit questionable? I don't know for sure, but mine seem to have found their happy place, running fine at 345 hrs TT.

Good luck!

[nucleus]

I think that the electronics in these are a little tender and the problem may be occurring after shutting off, they get too hot when all the cooling air stop blowing on them and the hot engine heats everything in the cowl up.

Hans

[Pirkka]

Just wondering if the heating is such a problem for these units, why there is no proper heat spreader in the unit itself. Area where the heat can radiate could be easily doubled or more with few fins. If the PWBs wouldn't get broken all the time the price of the units might be dropped... it seems to me that they are not willing to fix the real problem.

[Bob Martin]

I am watching this thread as I would like to install P-mags at some point and upgrade from mags.
I've noticed in my local area and other RV planes I've visited that some guys have the cabin heat selector valve installed upside down.
What I mean is the hot air from the exhaust muff is attached to the bottom of the valve and the un-used warmed air goes out the top, which in some locations is right below the right mag!
Now I think the proper installation would be hot air from the heat muff in the top and un-used warm air expelled towards the bottom cowl exit.
Just something to check!

[RV7Guy]

Originally Posted by Bob Martin

I've noticed in my local area and other RV planes I've visited that some guys have the cabin heat selector valve installed upside down.
What I mean is the hot air from the exhaust muff is attached to the bottom of the valve and the un-used warmed air goes out the top, which in some locations is right below the right mag!
Now I think the proper installation would be hot air from the heat muff in the top and un-used warm air expelled towards the bottom cowl exit.
Just something to check!

This is a good point Bob. I rebuilt my stainless steel heater box to vent the hot air down. I'm in AZ and fly in the heat, sometimes extreme heat and have not had a heat related issue ever. I do not have any cooling tubes on the units. Flew to my job yesterday and took off at 4 pm 106 degrees.

I had some early problems but have not any issues in over 200 hours.

[lostpilot28]

I hope I'm not deviating too much from the original thread, but I just finished installing my baffels and plenum...I did not install any blast tubes yet. Is this required? It seems like a good idea. What are you guys using for tubes and how do you attach them to the baffels?

Thanks.

[Davepar]

I just used the standard corrugated black tubing from Vans. Cut a hole in the baffles at a convenient spot. Make the size so it fits the smaller radius on the tubing. Tie-wrap the tubing so it points at the P-mag. Done deal.

I actually have a blast tube only on the right P-mag. Couldn't figure out a convenient method to cool the left one. My cabin heat selector valve dumps sideways and not up or down.

I haven't had any heat related problems in 130ish hours. Of course I do live in Seattle.

[lostpilot28]

Thanks Dave. I've seen a picture or two somewhere that somebody used metal tubing for blast tubes. Actually, it may have been the photo's that I got with my plenum from Sam James. I like the idea of using the plastic corrugated tubing better...lighter, flexible, easier to install (it seems).

[Davepar]

Yup, very easy to install. They are a bit difficult to aim precisely, though. Sorry I don't have a picture to show you.