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sportav8r(at)gmail.com
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 Posted: Tue Apr 28, 2009 4:48 pm Post subject: Electronic ignition question |
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Ok, guys - questions. Let's see if I can express this clearly while starting to chomp-down a frozen margarita...
I've got dual Pmags, model 112's, on my Lyc. Basically no trouble out of them for 100's of hours, except I removed and disabled the MP vacuum lines when one Pmag developed an internal vacuum sensor leak that was playing havoc with my manifold pressure readings... I knew an eventual upgrade to a newer Pmag model was in the cards when that happened, but have been putting it off. Recently replaced the plugs. Old ones looked really good, but I'm just anal about cheap & easy maintenance items like that.
Last flight, I noticed a significant discrepancy in mag drops at run-up: about 50 rpm on the right side, but 160 running on the left. Flew okay around the patch that day , but it got me to worrying a bit. Today, run-up performance was the same as the last time - big drop with the right side off. Still, I wanted to get some engine monitor number in flight to see what might be up.
When I shut off the left mag in level cruise, the rpm dropped slightly, and EGT's rose slightly on cyl's1& 2 (I can only read two at a time with my ancient EIS). When I shut off the right ignition, the EGT's again climbed, but the #2 went to redline immediately (and I mean fast, from 1510 to over 1600F) and the engine rpm drop was more pronounced. I repeated the test with the mixture full rich, and even though i was starting with EGT's in the 1380 range, the #2 went over 1600 again, just a little more slowly. In the seriousness of the moment, I never bothered to check cylinders 3&4; don't want a burnt valve or holed piston.
Realizing i had a situation that could damage the engine if I lost that right ignition in flight, I called it a day and decided it was a safety-of-flight issue that justified pulling the mags for replacement right away. Unfortunately, the Emagair folks are taking the slow boat home from Lakeland, and it will be Friday before anyone can return my calls. (Hey - I type okay when nursing a bit of tequila, eh?)
So here's the question: what's causing this behavior? I was expexting a lower EGT on one cylinder if it was not firing right, unless the timing has jumped. I can see how a very advanced timing on the left mag might shoot the EGT high,but why not on all cylinders? ANd if advanced timing is the cause, why not showing up when both ignitions are on? The right side would be firing too late to help things. I guess it must be retarded timing if anything, but I never knew that problem would drive the EGT up. A plug or wiring problem on cylinder 2 would make the cylinder run cold, not hot, would it not? I'm just really not sure what is going on here, but I am sure hoping a replacement of the mags with the latest, greatest model will fix it all. Even if resetting the timing on the left mag would fix the issue, I still am gong to pony up for the new mags, so I might as well take my down-time like a man and do what common sendse tells me need s to be done.
I would like to here what the hive mind thingks is up wityh my airplane . I don't liek not being able to fly for a coiupel of weeks.Now that I've have finished the margarita, the problem really doens't seem that serious. Thanks fro letting me get that offf my chest. Irt's getting dark but it's such a quite evening and the winds are calm. Screw it, I'm going flying whwther the P-mags coperate or not.
Shtormy
point me to th hangar, Mabel
[quote][b]
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Larry Bowen
Joined: 09 Jan 2006
Posts: 802
Location: NC, USA
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| Posted: Tue Apr 28, 2009 5:05 pm Post subject: Electronic ignition question |
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I'd say a bad plug or wire on #2, which would show cool CHTs and hot EGT. No?
One tequila, two tequila, three tequila, floor....
--
Larry Bowen
Larry(at)BowenAero.com
http://BowenAero.com
Sent from Welcome, NC, United States
On Tue, Apr 28, 2009 at 8:46 PM, Bill Boyd <sportav8r(at)gmail.com (sportav8r(at)gmail.com)> wrote:
[quote] Ok, guys - questions. Let's see if I can express this clearly while starting to chomp-down a frozen margarita...
I've got dual Pmags, model 112's, on my Lyc. Basically no trouble out of them for 100's of hours, except I removed and disabled the MP vacuum lines when one Pmag developed an internal vacuum sensor leak that was playing havoc with my manifold pressure readings... I knew an eventual upgrade to a newer Pmag model was in the cards when that happened, but have been putting it off. Recently replaced the plugs. Old ones looked really good, but I'm just anal about cheap & easy maintenance items like that.
Last flight, I noticed a significant discrepancy in mag drops at run-up: about 50 rpm on the right side, but 160 running on the left. Flew okay around the patch that day , but it got me to worrying a bit. Today, run-up performance was the same as the last time - big drop with the right side off. Still, I wanted to get some engine monitor number in flight to see what might be up.
When I shut off the left mag in level cruise, the rpm dropped slightly, and EGT's rose slightly on cyl's1& 2 (I can only read two at a time with my ancient EIS). When I shut off the right ignition, the EGT's again climbed, but the #2 went to redline immediately (and I mean fast, from 1510 to over 1600F) and the engine rpm drop was more pronounced. I repeated the test with the mixture full rich, and even though i was starting with EGT's in the 1380 range, the #2 went over 1600 again, just a little more slowly. In the seriousness of the moment, I never bothered to check cylinders 3&4; don't want a burnt valve or holed piston.
Realizing i had a situation that could damage the engine if I lost that right ignition in flight, I called it a day and decided it was a safety-of-flight issue that justified pulling the mags for replacement right away. Unfortunately, the Emagair folks are taking the slow boat home from Lakeland, and it will be Friday before anyone can return my calls. (Hey - I type okay when nursing a bit of tequila, eh?)
So here's the question: what's causing this behavior? I was expexting a lower EGT on one cylinder if it was not firing right, unless the timing has jumped. I can see how a very advanced timing on the left mag might shoot the EGT high,but why not on all cylinders? ANd if advanced timing is the cause, why not showing up when both ignitions are on? The right side would be firing too late to help things. I guess it must be retarded timing if anything, but I never knew that problem would drive the EGT up. A plug or wiring problem on cylinder 2 would make the cylinder run cold, not hot, would it not? I'm just really not sure what is going on here, but I am sure hoping a replacement of the mags with the latest, greatest model will fix it all. Even if resetting the timing on the left mag would fix the issue, I still am gong to pony up for the new mags, so I might as well take my down-time like a man and do what common sendse tells me need s to be done.
I would like to here what the hive mind thingks is up wityh my airplane . I don't liek not being able to fly for a coiupel of weeks.Now that I've have finished the margarita, the problem really doens't seem that serious. Thanks fro letting me get that offf my chest. Irt's getting dark but it's such a quite evening and the winds are calm. Screw it, I'm going flying whwther the P-mags coperate or not.
Shtormy
point me to th hangar, Mabel
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st" target="_blank">http://www.matronics.com/Navigator?RVSouthEast-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
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[b]
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Larry Bowen
RV-8 SOLD,
RV-7QB in progress... |
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bill(at)repucci.com
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| Posted: Tue Apr 28, 2009 5:49 pm Post subject: Electronic ignition question |
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That sounds reasonable. Stormy, now might be a good time to trade them in for the new 114 P-mags.
Bill
From: owner-rvsoutheast-list-server(at)matronics.com [mailto:owner-rvsoutheast-list-server(at)matronics.com] On Behalf Of Larry Bowen
Sent: Tuesday, April 28, 2009 9:05 PM
To: rvsoutheast-list(at)matronics.com
Subject: Re: Electronic ignition question
I'd say a bad plug or wire on #2, which would show cool CHTs and hot EGT. No?
One tequila, two tequila, three tequila, floor....
--
Larry Bowen
Larry(at)BowenAero.com
http://BowenAero.com
Sent from Welcome, NC, United States
On Tue, Apr 28, 2009 at 8:46 PM, Bill Boyd <sportav8r(at)gmail.com (sportav8r(at)gmail.com)> wrote:
Ok, guys - questions. Let's see if I can express this clearly while starting to chomp-down a frozen margarita...
I've got dual Pmags, model 112's, on my Lyc. Basically no trouble out of them for 100's of hours, except I removed and disabled the MP vacuum lines when one Pmag developed an internal vacuum sensor leak that was playing havoc with my manifold pressure readings... I knew an eventual upgrade to a newer Pmag model was in the cards when that happened, but have been putting it off. Recently replaced the plugs. Old ones looked really good, but I'm just anal about cheap & easy maintenance items like that.
Last flight, I noticed a significant discrepancy in mag drops at run-up: about 50 rpm on the right side, but 160 running on the left. Flew okay around the patch that day , but it got me to worrying a bit. Today, run-up performance was the same as the last time - big drop with the right side off. Still, I wanted to get some engine monitor number in flight to see what might be up.
When I shut off the left mag in level cruise, the rpm dropped slightly, and EGT's rose slightly on cyl's1& 2 (I can only read two at a time with my ancient EIS). When I shut off the right ignition, the EGT's again climbed, but the #2 went to redline immediately (and I mean fast, from 1510 to over 1600F) and the engine rpm drop was more pronounced. I repeated the test with the mixture full rich, and even though i was starting with EGT's in the 1380 range, the #2 went over 1600 again, just a little more slowly. In the seriousness of the moment, I never bothered to check cylinders 3&4; don't want a burnt valve or holed piston.
Realizing i had a situation that could damage the engine if I lost that right ignition in flight, I called it a day and decided it was a safety-of-flight issue that justified pulling the mags for replacement right away. Unfortunately, the Emagair folks are taking the slow boat home from Lakeland, and it will be Friday before anyone can return my calls. (Hey - I type okay when nursing a bit of tequila, eh?)
So here's the question: what's causing this behavior? I was expexting a lower EGT on one cylinder if it was not firing right, unless the timing has jumped. I can see how a very advanced timing on the left mag might shoot the EGT high,but why not on all cylinders? ANd if advanced timing is the cause, why not showing up when both ignitions are on? The right side would be firing too late to help things. I guess it must be retarded timing if anything, but I never knew that problem would drive the EGT up. A plug or wiring problem on cylinder 2 would make the cylinder run cold, not hot, would it not? I'm just really not sure what is going on here, but I am sure hoping a replacement of the mags with the latest, greatest model will fix it all. Even if resetting the timing on the left mag would fix the issue, I still am gong to pony up for the new mags, so I might as well take my down-time like a man and do what common sendse tells me need s to be done.
I would like to here what the hive mind thingks is up wityh my airplane . I don't liek not being able to fly for a coiupel of weeks.Now that I've have finished the margarita, the problem really doens't seem that serious. Thanks fro letting me get that offf my chest. Irt's getting dark but it's such a quite evening and the winds are calm. Screw it, I'm going flying whwther the P-mags coperate or not.
Shtormy
point me to th hangar, Mabel
| Quote: | | st" target="_blank">http://www.matronics.com/Navigator?RVSouthEast-Listtp://forums.matronics.com_blank">http://www.matronics.com/contribution |
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ceengland(at)bellsouth.ne
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| Posted: Tue Apr 28, 2009 5:50 pm Post subject: Electronic ignition question |
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Bill Boyd wrote:
| Quote: | Ok, guys - questions. Let's see if I can express this clearly while
starting to chomp-down a frozen margarita...
I've got dual Pmags, model 112's, on my Lyc. Basically no trouble out
of them for 100's of hours, except I removed and disabled the MP
vacuum lines when one Pmag developed an internal vacuum sensor leak
that was playing havoc with my manifold pressure readings... I knew an
eventual upgrade to a newer Pmag model was in the cards when that
happened, but have been putting it off. Recently replaced the plugs.
Old ones looked really good, but I'm just anal about cheap & easy
maintenance items like that.
Last flight, I noticed a significant discrepancy in mag drops at
run-up: about 50 rpm on the right side, but 160 running on the left.
Flew okay around the patch that day , but it got me to worrying a
bit. Today, run-up performance was the same as the last time - big
drop with the right side off. Still, I wanted to get some engine
monitor number in flight to see what might be up.
When I shut off the left mag in level cruise, the rpm dropped
slightly, and EGT's rose slightly on cyl's1& 2 (I can only read two at
a time with my ancient EIS). When I shut off the right ignition, the
EGT's again climbed, but the #2 went to redline immediately (and I
mean fast, from 1510 to over 1600F) and the engine rpm drop was more
pronounced. I repeated the test with the mixture full rich, and even
though i was starting with EGT's in the 1380 range, the #2 went over
1600 again, just a little more slowly. In the seriousness of the
moment, I never bothered to check cylinders 3&4; don't want a burnt
valve or holed piston.
Realizing i had a situation that could damage the engine if I lost
that right ignition in flight, I called it a day and decided it was a
safety-of-flight issue that justified pulling the mags for replacement
right away. Unfortunately, the Emagair folks are taking the slow boat
home from Lakeland, and it will be Friday before anyone can return my
calls. (Hey - I type okay when nursing a bit of tequila, eh?)
So here's the question: what's causing this behavior? I was expexting
a lower EGT on one cylinder if it was not firing right, unless the
timing has jumped. I can see how a very advanced timing on the left
mag might shoot the EGT high,but why not on all cylinders? ANd if
advanced timing is the cause, why not showing up when both ignitions
are on? The right side would be firing too late to help things. I
guess it must be retarded timing if anything, but I never knew that
problem would drive the EGT up. A plug or wiring problem on cylinder 2
would make the cylinder run cold, not hot, would it not? I'm just
really not sure what is going on here, but I am sure hoping a
replacement of the mags with the latest, greatest model will fix it
all. Even if resetting the timing on the left mag would fix the
issue, I still am gong to pony up for the new mags, so I might as well
take my down-time like a man and do what common sendse tells me need s
to be done.
|
snip
Don't know much about p/e mags, but late timing will drive cht down &
egt up. Fuel is burning in the exhaust pipe instead of in the cylinder.
Charlie
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sportav8r(at)gmail.com
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| Posted: Tue Apr 28, 2009 6:35 pm Post subject: Electronic ignition question |
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Okay, I'll check the plugs and wiring first. I'd hate to install new mags and still have the same issues. But the 114's are on my immediate do-list anyhow.
-Stormy
It was a smallish margarita, actually. Just playin' with you guys.
[quote][b]
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