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05-27-2020, 07:44 AM
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Join Date: Mar 2017
Location: Birmingham, Alabama
Posts: 1,643
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Quote:
Originally Posted by GalinHdz
Yes I know the manual says TDC but if it worked then and doesn't work now the equipment is trying to tell you something and I would listen.
FWIW my pMag install works best when set at 1* AFTER TDC.

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Mine seem to run great at 25*btdc but curious what process did you use to determine that 1* worked for you?
We have a new 14 on the field as of yesterday and the builder (Synergy Air) has the engine idling at 1050 and it runs rough as heck, I think somebody adjusted the idle because they didn't properly time the PMAGs to the IO390, haven't done any investigation yet, just the first thing that came to mind.
(sorry for the thread drift but something may come that helps)
__________________
RV-14A #140376
N196 (Flying)
2019 Bronze Lindy
Last edited by bkervaski : 05-27-2020 at 08:00 AM.
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05-27-2020, 07:51 AM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Quote:
Originally Posted by Skysailor
Take a look at the wires in the connector on the Pmag. I have the jumper installed (as do most). The only problem I had with my Pmag was due to one end of the jumper not being tight in the connector. This caused the timing to change as the loose jumper made and un-made contact. Inspect the pins in the connector to verify they are clean when you check this. Certainly a quick simple check.
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The P-mags only check for the jumper at start-up. Once they are spinning, you could remove the jumper and it wouldn't matter.
Over the long weekend I helped two different local pilots with P-mag issues. One had a broken plug wire clip at the sparkplug. Push on all the connectors, both at the cool pack and at the sparkplug. If it moves at all, investigate further.
The other was really odd in that sometimes the P-mag would work fine and another time in the same flight it wouldn't work at all.
Both pilots are sending their P-mags back for inspection and repair just to be safe.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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05-27-2020, 07:53 AM
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Join Date: Mar 2010
Location: KSGJ / TJBQ
Posts: 2,039
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Quote:
Originally Posted by bkervaski
Mine seem to run great at 25btdc but curious what process did you use to determine that 1* worked for you?
We have a new 14 on the field as of yesterday and the builder (Synergy Air) has the engine idling at 1050 and it runs rough as heck, I think somebody adjusted the idle because they didn't properly time the PMAGs to the IO390, haven't done any investigation yet, just the first thing that came to mind.
(sorry for the thread drift but something may come that helps)
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After talking with Brad at eMags and some trial and error i settled on the 1*ATDC. I guess if you have an EI commander finding the "sweet spot" would be easier but don't know. At about 1* ATDC my engine runs smoothest while the CHT's stay within a very acceptable range.
To avoid confusion; the Pmags don't get set to 25*BTDC they get set to TDC and the internal program adjusts the spark to fire at 25*BTDC, but I guess you already knew that. In my case, since I set mine to 1* ATDC, they are actually firing at 24*BTDC.

__________________
Galin
CP-ASEL-AMEL-IR
FCC Radiotelephone (PG) with Radar Endorsement
2020 Donation made
www.PuertoRicoFlyer.com
Last edited by GalinHdz : 05-27-2020 at 08:14 AM.
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05-27-2020, 08:06 AM
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Join Date: Mar 2017
Location: Birmingham, Alabama
Posts: 1,643
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Quote:
Originally Posted by GalinHdz
To avoid confusion; the Pmags don't get set to 25BTDC they get set to TDC and the internal program adjusts the spark to 25*BTDC, but I guess you already knew that.

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Oh, roger! Correct ... thanks for the clarification.
__________________
RV-14A #140376
N196 (Flying)
2019 Bronze Lindy
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05-27-2020, 09:14 AM
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Join Date: Jul 2007
Location: Taylorsville, Ga
Posts: 798
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Kyle, are you at KVPC trouble shooting this?, if so give me a call and I will help or at least provide a second set of eyes ( with glasses). Text is fine.
__________________
DRRhodes
2020 VAF Supporter
RV9 N908DR
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05-27-2020, 09:22 AM
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Join Date: Feb 2016
Location: VA
Posts: 37
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Not timed correctly
One of your magnetos isn't correctly timed or someone dropped a spark-plug. Oh, wait electronic mag? Forget it. I only know about the stuff that's worked for the past 100 years.
I don't know what you mean by pMag, that must be experimental lingo for the magneto with the impulse coupling? If your engine starts, the impulse coupling did it's job. What releases or disconnects the impulse coupling are "flyweights" that when spun, disengage the retarding of the mag. I would look at everything else before the impulse coupling.
Last edited by DTARM1 : 05-27-2020 at 09:25 AM.
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05-27-2020, 09:40 AM
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Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
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It is unlikely that this is caused by your 6 pin wire plugs since once the PMAG is running, its dependency on the power/GND goes away unless below 800-900 RPM, and if it was dependent on that, it would probably just not produce any spark and engine would die.
I know you have checked the sparkplug and its gap, but perhaps if you get one new sets of spark plug and try them. If it was not, it will not be waste of money as you will use them on your next annual. Same thought with your Spark plug wires.
Lastly, maybe checking the timing by pulling the plugs and connecting them to the spark plug wires and grounded and as you turn the prop, check for the spark at each spark plug to make sure they fire correctly and all four will fire. If you do that, make sure your slick mag is off or perhaps not connected at all to make sure the engine will not accidently fire up as you are turning the prop.
Hope this helps.
__________________
Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
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05-27-2020, 09:41 AM
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Join Date: Nov 2014
Location: Richmond Hill, GA (KLHW)
Posts: 2,189
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Quote:
Originally Posted by DTARM1
One of your magnetos isn't correctly timed or someone dropped a spark-plug. Oh, wait electronic mag? Forget it. I only know about the stuff that's worked for the past 100 years.
I don't know what you mean by pMag, that must be experimental lingo for the magneto with the impulse coupling? If your engine starts, the impulse coupling did it's job. What releases or disconnects the impulse coupling are "flyweights" that when spun, disengage the retarding of the mag. I would look at everything else before the impulse coupling.
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P-Mag is made by E-Magair, an electronic ignition. No impulse coupler involved. Most people replace the impulse coupled mag due to its higher likely hood of failure.
__________________
Ray
RV-7A - Slider - N495KL - First flt 27 Jan 17
O-360-A4M w/ AFP FM-150 FI, Dual PMags, Vetterman Trombone Exh, SkyTech starter, BandC Alt (PP failed after 226 hrs)
Catto 3 blade NLE, FlightLines Interior, James cowl, plenum & intake, Anti-Splat -14 seat mod and nose gear support
All lines by TSFlightLines (aka Hoser)
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05-27-2020, 09:56 AM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Quote:
Originally Posted by DTARM1
One of your magnetos isn't correctly timed or someone dropped a spark-plug. Oh, wait electronic mag? Forget it. I only know about the stuff that's worked for the past 100 years.
I don't know what you mean by pMag, that must be experimental lingo for the magneto with the impulse coupling? If your engine starts, the impulse coupling did it's job. What releases or disconnects the impulse coupling are "flyweights" that when spun, disengage the retarding of the mag. I would look at everything else before the impulse coupling.
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You mean those archaic tractor ignitions that are prone to failure at any time, without warning?
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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05-27-2020, 10:02 AM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Quote:
Originally Posted by Bavafa
It is unlikely that this is caused by your 6 pin wire plugs since once the PMAG is running, its dependency on the power/GND goes away unless below 800-900 RPM, and if it was dependent on that, it would probably just not produce any spark and engine would die.
I know you have checked the sparkplug and its gap, but perhaps if you get one new sets of spark plug and try them. If it was not, it will not be waste of money as you will use them on your next annual. Same thought with your Spark plug wires.
Lastly, maybe checking the timing by pulling the plugs and connecting them to the spark plug wires and grounded and as you turn the prop, check for the spark at each spark plug to make sure they fire correctly and all four will fire. If you do that, make sure your slick mag is off or perhaps not connected at all to make sure the engine will not accidently fire up as you are turning the prop.
Hope this helps.
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The following assumes you have your P-mags timed to TDC.
If you attempt this, the P-mags will fire at 4.2 degrees after TDC when below 400 RPM's. It does this to assist in starting. Call it an electronic impulse coupler, if you will.
Please be sure to remove at least one plug from each cylinder so the engine won't "kick" and hurt you or anyone standing close by.
I personally doubt this is the issue, but you never know.
Kyle, check your PM's.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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