R

RKellogg

Well Known Member
A week ago I posted a request for advice about a recent engine roughness issue. The IO-360 (C/S prop, dual P-Mag, AFP injection, 32 hours since new) had developed a distinct roughness when operating on both P-Mags, which went away when operating on either P-Mag alone. The roughness was felt through the floor, and other parts of the airframe structure. Advice from several posters, especially N941WR, helped focus efforts to a solution.

Yesterday I was able to get back to the hanger, and found that both P-Mags were timed 3 degrees before top center. I was also surprised to see that the A-curve jumpers had never been installed as intended. Re-timing to TDC and adding the A-curve jumper essentially retarded timing by eight degrees.

Two hours of test flight proved that the dual mag roughness was gone. So apparently the over advanced timing was creating roughness when operating on two mags, but when operating on a either mag alone the timing was retarded just enough to prevent the roughness. The roughness was subtle, but I suspect that it would have caused premature engine problems. Now I know what over-advanced ignition timing feels like.

Still not sure why / how the timing jumped by three degrees, both mags. My perception was that the roughness started abruptly on climb-out, but cannot be sure.

I intend to add an EICommander to the panel. This is a device that monitors the health of P-Mags during operation and allows additional manipulation of their performance.

Thanks to all who helped put the RV grin back on my face! And thanks to DR for keeping this great asset growing

- Roger
 
How can the timing change after 32 hrs? I understood that it had been running smoothly up to then?
 
Great to hear the solution was that simple! I wish you many more trouble free hours! Don't hesitate to call, if you have any other questions.

sblack said:
How can the timing change after 32 hrs? I understood that it had been running smoothly up to then?
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It can't, unless the retaining nuts come loose and the P-mags turn but that didn't happen. They probably were not timed correctly from the beginning and it took him a few hours to recognize there was an issue.
 
Roger,

I am glad you fixed this up.

I would suggest setting the PMAG a degree or two past top dead centre, and on the less aggressive curve.

;)
 
RV10inOz said:
Roger,

I am glad you fixed this up.

I would suggest setting the PMAG a degree or two past top dead centre, and on the less aggressive curve.

;)
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As of firmware version 40, it is no longer nessisary to set them a degree or two past TDC. The reason is that that version now fires the plugs at four degrees past TDC for starting.
 
Thats a good thing, but I was meaning as an offset from the extra advance, a tiny bit helps, when LOP but they still have a bit too much otherwise in my opinion.

Each to their own. :)
 
Timing

When timing the engine get to TDC by turning the engine forward ONLY! If you turn it backwards the lash in the acc case gears will give you the result you had. Be safe!
 
RKellogg said:
So apparently the over advanced timing was creating roughness when operating on two mags, but when operating on a either mag alone the timing was retarded just enough to prevent the roughness.
Click to expand...

This is typical. Dual plug setups require less advance than a single plug setup. In recip engines, it's all about timing the max pressure induced by the burning a/f mixture to occur just past TDC. Two ignitions from opposite sides of the cylinder will take less time to reach this max pressure point than one spark. There can be roughness when too much advance is in place, but surprised you could feel 3 degrees. I am still learning about lycomings.

Larry
 
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RV10inOz said:
Thats a good thing, but I was meaning as an offset from the extra advance, a tiny bit helps, when LOP but they still have a bit too much otherwise in my opinion.

Each to their own. :)
Click to expand...

Using the EICommander i'm running a negative 1.4 on the A curve which has been working nicely with Dual P-Mags. Nice to have the instrumentation and control over them.
 
N941WR said:
As of firmware version 40, it is no longer nessisary to set them a degree or two past TDC. The reason is that that version now fires the plugs at four degrees past TDC for starting.
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How can we find out which firmware version we have and I assume updating it will require it to be sent back to the factory, correct?
 
sblack said:
How can the timing change after 32 hrs? I understood that it had been running smoothly up to then?
Click to expand...

N941WR said:
It can't, unless the retaining nuts come loose and the P-mags turn but that didn't happen.
Click to expand...

Not sure I am buying that.
I thought the timing mark on the Emagair units was a number that is compared to the count of a randomly installed rotary encoder. We have seen uncommanded timing changes on early emagair units reported here. Giving emagair its due, it has been stated that those failure modes have been addressed and it has been a long time since any have been noted. However, it is not clear to me how this "count number" is hardened against all electromagnetic intrusion including cosmic ray degradation. I don't like inability to set these mechanically (as I was told by Brad) to eliminate the reliance on the puff number.
 
Bavafa said:
How can we find out which firmware version we have and I assume updating it will require it to be sent back to the factory, correct?
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There are four ways:
1) Write your own code to connect to the P-mags and trigger the streaming data.
2) Install an EICommander and have it tell you what version you are running.
3) Connect to them with the EICAD program and have it tell you.
4) Look at the sticker on the body of the P-mag and the version number should be written on there.

Version 40 just came out on 9/26/2014, so if your P-mag is older than that or hasn't been back for an upgrade, chances are you are not running Version 40.
 
N941WR said:
There are four ways:
1) Write your own code to connect to the P-mags and trigger the streaming data.
2) Install an EICommander and have it tell you what version you are running.
3) Connect to them with the EICAD program and have it tell you.
4) Look at the sticker on the body of the P-mag and the version number should be written on there.

Version 40 just came out on 9/26/2014, so if your P-mag is older than that or hasn't been back for an upgrade, chances are you are not running Version 40.
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Awesome and thanks for the info. Now, would I need to send it back for the firmware update or can it be done with EICommander?
 
Bavafa said:
Awesome and thanks for the info. Now, would I need to send it back for the firmware update or can it be done with EICommander?
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No, we have discussed allowing the EIC to push updates to the P-mags and we both agree that we don't want to do it. It is best for your safety to send the ignition back to the manufacture for the update.
 
N941WR said:
As of firmware version 40, it is no longer nessisary to set them a degree or two past TDC. The reason is that that version now fires the plugs at four degrees past TDC for starting.
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Hello Bill and other guys
my question:
should be compatible one Pmag firmware 36 (mine bought one and half years ago) with a new one with firmware 40?
How can I set both at the same retard BTDC?
Or I need/must upgrade the older one? (@#!"&=ยง% shipping back in US from Italy)

Thanks in advance for you suggestion
LC
 
While you can always send the older one in for the update, it really isn't necessary, unless you have a lightweight prop. If you have a metal prop, I would set both P-mags the same.

At your next condition inspection I would send the older one in for the update, just to make sure they are the same.

Clocking your older P-mag a few degrees means they won't fire at the same time and you lose any advantage of having identical ignitions.
 
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Bill,

Can you point me to a resource that describes the various firmware updates?

Thanks

Bevan
 
N941WR said:
While you can always send the older one in for the update, it really isn't necessary, unless you have a lightweight prop...
..I would send the older one in for the update, just to make sure they are the same.

Clocking your older P-mag a few degrees means they won't fire at the same time and you lose any advantage of having identical ignitions.
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Yess Bill , I've a light prop, that is 3 blade Catto.
**** I need / better send it back for update

I'm not electronic expert but, thinking about at some popular efis I don't understand why is not possible to update a PMag via software; in that way the product would gain added value.

Thanks a lot
Lucio
 
Lucio I-NLCM said:
Yess Bill , I've a light prop, that is 3 blade Catto.
**** I need / better send it back for update

I'm not electronic expert but, thinking about at some popular efis I don't understand why is not possible to update a PMag via software; in that way the product would gain added value.

Thanks a lot
Lucio
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I hear what you are saying but a plane will still fly with a bad software update to an EFIS but a bad software load to your ignition is another matter. Besides, it gives them a chance to inspect the P-mags for unexpected wear. Maybe in the future, they will allow us to do the upgrades.
 
OK Thanks.

Does this mean that without V40, one should not turn the engine with the starter while the Pmags are NOT powered (pmags un-grounded) for a little pre-lube/pre-pressurization prior to engine start? I would only do this if the engine has not been run for an unusually long time.

Bevan
 
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