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Problem during mag check

dsyvert2

Well Known Member
I was doing a run up check and I had something odd happen. I took the rpm up to 1700 rpm. I checked the right mag and the rpm dropped to 1550 rpm. Back to both and it went back to 1700 rpm. Left mag check, the engine started dying. Went back to both and it went to 1700 rpm. I repeated it several times ? both 1700, right 1550, left ? engine dies.

I got an A&P mechanic and we discussed it. Our conclusion was the Slick mags were ok because of the rpm rise from just right mag to both mags. It seemed like the most logical explanation was the ignition switch. We installed a new ignition switch. Tried the mag check again and the results were the same ? both 1700, right 1550, left ? engine dies.

Any ideas?

Dave Syvertson
 
when this happened to me it turned out to be a bad ignition coil - but i have mags plus LSI

do you have dual mags or some sort of eletronic ignition?
 
Could it be that you were not starting your check from the "both" position? ;)
If the switch isn't in both but actually is in the "right" mag, your first check will actually be the left mag, and your second check will be the off position. Not that I would ever have done this , but I have a "friend" who did this once with the same result you are experiencing.

Chris
 
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