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apatton2

Joined: 17 Jan 2018
Posts: 27

Posted: Mon Jun 18, 2018 9:35 pm Post subject: Engine running rough at high power settings?

O Gods of M14:

Here's a riddle for you.



I have a Yak-50 with a stock M14P. I have been flying it regularly since I purchased it around 8mo and 40hr ago. It is a very stock airplane (no digital engine monitor, etc). TTA&E 640h.



Before I flew it for the first time, I replaced the following with new/overhauled components:

- spark plugs (auto kit)

- Mags (overhauled M9F)

- Carb (overhauled)



So, now all of those components have around 40hrs on them.



2 weekends ago I had the engine run very rough on climbout. I continued around the pattern and landed. Mag check was nominal (as it was prior to takeoff). Tried again and felt enough engine vibe on takeoff roll to abort. Mag check again nominal.



Brought it back to hangar. Uncowled; visually inspected. Found some cracked ignition lead boots (4 of the 9 on the rear cylinders). So I replaced all ignition leads with new ones (auto harnesses).



Tried it again today. Same issue on takeoff. Feels like it's missing significant power / climbing more slowly. This time pulled throttle and prop back to 70% rpm upon reaching 500' (airport is sea level). It smoothed out *very* quickly with the throttle and prop pulled back (especially when i brought prop lever back under 80%). On the ground it again mag checked nominal (both <3> 80%). Don't know what to make of this.



Any thoughts on where to go next? I haven't pulled the plugs yet but may do that next - or check carb settings.

Thanks!

Andrew

_________________
Andrew Patton
Yak-50
San Francisco, CA

mark.bitterlich(at)navy.m
Guest

Posted: Tue Jun 19, 2018 7:55 am Post subject: Engine running rough at high power settings?

Besides checking the mags when it is actually happening, ... not afterwards, but when it is actually happening.... you also need to check your primer pump.  There are many ways to do this, but my preferred method is to turn the handle to the PRIME direction, which in a 50 should be to the left (to the right on a 52), listen to the engine at idle.  It should have an RPM decrease and run rough, reason being that with the primer pump handle turned left, the engine will run extremely rich and you should be able to not only hear this, but also to hear it go away and return to smooth running when you put it back in the middle.   If you do NOT hear any difference between middle and to the left, it is possible your primer pump is leaking internally and making the engine way too rich.  You would feel this on takeoff.  Pulling the engine back, I.E. unloading power would smooth it out.  And of course, this is a long shot.  Typically "rough on climb out" is a mag thing.  Since it ran well for awhile after rebuild, the assumption is that they were both re-installed and timed correctly, although that is a leap of faith because aligning a M-14 MAG is rather an art form.  See Dennis for details.  So if you check the mags in flight (or have already done so) and there is no change running from one mag to the other, it comes to fuel.  The primer pump is always a possible culprit.  Following that induction leaks.  It is very possible that you could have an induction tube or two sucking in air making a few cylinders go lean.  This would also smooth out when pulling back on the power.  So look for loose induction tube rings and seals as this too is a common problem.  Following that is the carb, and hopefully nobody has to go there.



Mark

--

byronmfox(at)gmail.com
Guest

Posted: Tue Jun 19, 2018 8:05 am Post subject: Engine running rough at high power settings?

Andrew, have you discussed this with Vladimir Yastremski? 



Blitz Fox415-307-2405





On Jun 18, 2018, at 10:35 PM, apatton2 <apatton(at)alumni.princeton.edu (apatton(at)alumni.princeton.edu)> wrote:

 	  Quote: 	
		  --> Yak-List message posted by: "apatton2" <apatton(at)alumni.princeton.edu (apatton(at)alumni.princeton.edu)>



O Gods of M14:

Here's a riddle for you.



I have a Yak-50 with a stock M14P. I have been flying it regularly since I purchased it around 8mo and 40hr ago. It is a very stock airplane (no digital engine monitor, etc). TTA&E 640h.



Before I flew it for the first time, I replaced the following with new/overhauled components:

- spark plugs (auto kit)

- Mags (overhauled M9F)

- Carb (overhauled)



So, now all of those components have around 40hrs on them.



2 weekends ago I had the engine run very rough on climbout. I continued around the pattern and landed. Mag check was nominal (as it was prior to takeoff). Tried again and felt enough engine vibe on takeoff roll to abort. Mag check again nominal.



Brought it back to hangar. Uncowled; visually inspected. Found some cracked ignition lead boots (4 of the 9 on the rear cylinders). So I replaced all ignition leads with new ones (auto harnesses).



Tried it again today. Same issue on takeoff. Feels like it's missing significant power / climbing more slowly. This time pulled throttle and prop back to 70% rpm upon reaching 500' (airport is sea level). It smoothed out *very* quickly with the throttle and prop pulled back (especially when i brought prop lever back under 80%). On the ground it again mag checked nominal (both  80%). Don't know what to make of this.



Any thoughts on where to go next? I haven't pulled the plugs yet but may do that next - or check carb settings.

Thanks!

Andrew



--------

Andrew Patton

Yak-50

San Francisco, CA





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=480979#480979

http://forums.matronics.com[/url]http://wiki.matronics.com



======================================================

richard.goode(at)russiana
Guest

Posted: Tue Jun 19, 2018 8:29 am Post subject: Engine running rough at high power settings?

Hello Andrew,



I would suspect an ignition problem, and probably the "traditional" problem

of a magneto coil breaking down. I'm very conscious that we sold you some

magnetos last year, and I would suspect that you aircraft probably has got

"our" magnetos fitted!



But where I have a question is that your problem seems to occur before the

engine is really hot - i.e. on take-off. Of course it will have been warmed

up and able to accept full power, but my experience of magneto coil issues

is that they do happen when the engine has been running for at least 20

minutes or so and heat has soaked right through the engine to the magnetos

and then to the coil.



In your case it does seem that the failure is shortly after take-off when

the magnetos are not going to be at their hottest.



But an obvious thing to do is to replicate the problem and then land and

check your sparking plugs - if one of the magnetos has not been working

correctly, this will be very obvious.



But if there's anything else, please come back to me on my direct email.



Richard



Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5 3LW



Tel:  +44 (0) 1544 340120

Fax: +44 (0) 1544 340129

www.russianaeros.com

--

dsavarese0812(at)bellsout
Guest

Posted: Tue Jun 19, 2018 9:55 am Post subject: Engine running rough at high power settings?

Could also be a sticking valve or valves.  Add a quart or so of Marvel Mystery Oil to the engine oil tank and run the engine for a couple of hours and see if that makes a difference.  The MMO will "clean" the crud off the valve guides, thus eliminating a sticking valve.  BTW, this is a common problem for the M14 and the MMO has proven to be a reliable fix.

Dennis

       From: Richard Goode <richard.goode(at)russianaeros.com>

 To: yak-list(at)matronics.com 

 Sent: Tuesday, June 19, 2018 12:31 PM

 Subject: RE: Engine running rough at high power settings?

--> Yak-List message posted by: "Richard Goode" <richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)>

Hello Andrew,

I would suspect an ignition problem, and probably the "traditional" problem

of a magneto coil breaking down. I'm very conscious that we sold you some

magnetos last year, and I would suspect that you aircraft probably has got

"our" magnetos fitted!

But where I have a question is that your problem seems to occur before the

engine is really hot - i.e. on take-off. Of course it will have been warmed

up and able to accept full power, but my experience of magneto coil issues

is that they do happen when the engine has been running for at least 20

minutes or so and heat has soaked right through the engine to the magnetos

and then to the coil.

In your case it does seem that the failure is shortly after take-off when

the magnetos are not going to be at their hottest.

But an obvious thing to do is to replicate the problem and then land and

check your sparking plugs - if one of the magnetos has not been working

correctly, this will be very obvious.

But if there's anything else, please come back to me on my direct email.

Richard

Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5 3LW

Tel:  +44 (0) 1544 340120

Fax: +44 (0) 1544 340129

www.russianaeros.com

--

captPod

Joined: 06 Jan 2014
Posts: 17

Posted: Tue Jun 19, 2018 11:16 am Post subject: Engine running rough at high power settings?

Dennis, What do you recommend doing with the oil after the couple of hour run? Change immediately? After x hours? At next scheduled oil change?I like MMO but have reservations in engine oil. 

Thanks, â€œ Podâ€

Sent from Yahoo Mail for iPhone

On Tuesday, June 19, 2018, 1:54 PM, A. Dennis Savarese <dsavarese0812(at)bellsouth.net> wrote:[quote]Could also be a sticking valve or valves.  Add a quart or so of Marvel Mystery Oil to the engine oil tank and run the engine for a couple of hours and see if that makes a difference.  The MMO will "clean" the crud off the valve guides, thus eliminating a sticking valve.  BTW, this is a common problem for the M14 and the MMO has proven to be a reliable fix.

Dennis



       From: Richard Goode <richard.goode(at)russianaeros.com>

 To: yak-list(at)matronics.com 

 Sent: Tuesday, June 19, 2018 12:31 PM

 Subject: RE: Engine running rough at high power settings?

  

 

--> Yak-List message posted by: "Richard Goode" <richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)>



Hello Andrew,



I would suspect an ignition problem, and probably the "traditional" problem



of a magneto coil breaking down. I'm very conscious that we sold you some



magnetos last year, and I would suspect that you aircraft probably has got



"our" magnetos fitted!



But where I have a question is that your problem seems to occur before the



engine is really hot - i.e. on take-off. Of course it will have been warmed



up and able to accept full power, but my experience of magneto coil issues



is that they do happen when the engine has been running for at least 20



minutes or so and heat has soaked right through the engine to the magnetos



and then to the coil.



In your case it does seem that the failure is shortly after take-off when



the magnetos are not going to be at their hottest.



But an obvious thing to do is to replicate the problem and then land and



check your sparking plugs - if one of the magnetos has not been working



correctly, this will be very obvious.



But if there's anything else, please come back to me on my direct email.



Richard



Richard Goode Aerobatics



Rhodds Farm



Lyonshall



Hereford



HR5 3LW



Tel:  [url=tel:+44%201544%20340120]+44 (0) 1544 340120[/url]



Fax: [url=tel:+44%201544%20340129]+44 (0) 1544 340129[/url]



www.russianaeros.com



--

Viperdoc

Joined: 19 Apr 2014
Posts: 484
Location: 08A

Posted: Tue Jun 19, 2018 11:39 am Post subject: Engine running rough at high power settings?

Sea Foam works very well at dissolving the sludge. Change the oil after running for on hour. Then I run it regularly in the oil. It is the similar if the same as itâ€™s more expensive STCâ€™d Camguard. 

Doc



Sent from my iPad



[quote] On Jun 19, 2018, at 2:11 PM, Michael Foster <michaelfoster(at)bellsouth.net> wrote:

 

 Dennis, What do you recommend doing with the oil after the couple of hour run? Change immediately? After x hours? At next scheduled oil change?

 I like MMO but have reservations in engine oil. 

 Thanks, â€œ Podâ€

 

 

 Sent from Yahoo Mail for iPhone

 

 On Tuesday, June 19, 2018, 1:54 PM, A. Dennis Savarese <dsavarese0812(at)bellsouth.net> wrote:

 

 Could also be a sticking valve or valves.  Add a quart or so of Marvel Mystery Oil to the engine oil tank and run the engine for a couple of hours and see if that makes a difference.  The MMO will "clean" the crud off the valve guides, thus eliminating a sticking valve.  BTW, this is a common problem for the M14 and the MMO has proven to be a reliable fix.

 Dennis

 

 

 From: Richard Goode <richard.goode(at)russianaeros.com>

 To: yak-list(at)matronics.com 

 Sent: Tuesday, June 19, 2018 12:31 PM

 Subject: RE: Engine running rough at high power settings?

 

 

 

 Hello Andrew,

 

 I would suspect an ignition problem, and probably the "traditional" problem

 of a magneto coil breaking down. I'm very conscious that we sold you some

 magnetos last year, and I would suspect that you aircraft probably has got

 "our" magnetos fitted!

 

 But where I have a question is that your problem seems to occur before the

 engine is really hot - i.e. on take-off. Of course it will have been warmed

 up and able to accept full power, but my experience of magneto coil issues

 is that they do happen when the engine has been running for at least 20

 minutes or so and heat has soaked right through the engine to the magnetos

 and then to the coil.

 

 In your case it does seem that the failure is shortly after take-off when

 the magnetos are not going to be at their hottest.

 

 But an obvious thing to do is to replicate the problem and then land and

 check your sparking plugs - if one of the magnetos has not been working

 correctly, this will be very obvious.

 

 But if there's anything else, please come back to me on my direct email.

 

 Richard

 

 Richard Goode Aerobatics

 Rhodds Farm

 Lyonshall

 Hereford

 HR5 3LW

 

 Tel:  +44 (0) 1544 340120

 Fax: +44 (0) 1544 340129

 www.russianaeros.com

 

 

 --

_________________
Viperdoc

mark.bitterlich(at)navy.m
Guest

Posted: Tue Jun 19, 2018 11:43 am Post subject: Engine running rough at high power settings?

I'd also add a quart to the fuel.     Way too much I know, but I've been doing it for 18 years now.



Mark

--

apatton2

Joined: 17 Jan 2018
Posts: 27

Posted: Tue Jun 19, 2018 11:51 am Post subject: Re: Engine running rough at high power settings?

Firstly: huge thanks for all the responses! 

Richard - yes, I am having a hard time believing that it could be a ignition coil, with the overhauled mags being so young. But I will try to t/s again in a few days with an in-air mag check. I have been rather focused on getting the airplane safely on deck during the past 2 flights.



Dennis - is there a way to visually verify sludge buildups on the valve guides as you describe? I have access to a borescope.



Mark - I think that both mags were reinstalled and timed correctly (an A&P friend and I did this). When opening them up to change harnesses they both looked clean, for whatever that's worth - I realize coils could still be bad.

Will check primer.

Re: induction system seals - are those o-ring type seals? I'm unfamiliar with them. Are the connections between the intake tubes and the case typically suspect, or is it the tubes and cylinders?

_________________
Andrew Patton
Yak-50
San Francisco, CA

mark.bitterlich(at)navy.m
Guest

Posted: Tue Jun 19, 2018 11:57 am Post subject: Engine running rough at high power settings?

Yes, I've run Sea Foam myself.  Good stuff.   And Doc's answer is also correct as for what to do afterwards.  Run it an hour or two and then drain all of it and replace with fresh oil, and you might want to inspect the oil filter as well.



Mark

--

dsavarese0812(at)bellsout
Guest

Posted: Tue Jun 19, 2018 12:06 pm Post subject: Engine running rough at high power settings?

Michael,

If you read the instructions on the MMO container, it is recommended for use in the oil AND the fuel.   



I'd drain the oil after a couple of hours run time and put fresh oil in the engine.

Dennis



       From: Michael Foster <michaelfoster(at)bellsouth.net>

 To: yak-list(at)matronics.com 

 Sent: Tuesday, June 19, 2018 3:18 PM

 Subject: Re: Engine running rough at high power settings?

  

 

 Dennis, What do you recommend doing with the oil after the couple of hour run? Change immediately? After x hours? At next scheduled oil change?I like MMO but have reservations in engine oil. 

Thanks, â€œ Podâ€Sent from Yahoo Mail for iPhoneOn Tuesday, June 19, 2018, 1:54 PM, A. Dennis Savarese <dsavarese0812(at)bellsouth.net> wrote:

[quote]Could also be a sticking valve or valves.  Add a quart or so of Marvel Mystery Oil to the engine oil tank and run the engine for a couple of hours and see if that makes a difference.  The MMO will "clean" the crud off the valve guides, thus eliminating a sticking valve.  BTW, this is a common problem for the M14 and the MMO has proven to be a reliable fix.

Dennis



       From: Richard Goode <richard.goode(at)russianaeros.com> To: yak-list(at)matronics.com  Sent: Tuesday, June 19, 2018 12:31 PM Subject: RE: Engine running rough at high power settings?  

 --> Yak-List message posted by: "Richard Goode" <richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)>



Hello Andrew,



I would suspect an ignition problem, and probably the "traditional" problem

of a magneto coil breaking down. I'm very conscious that we sold you some

magnetos last year, and I would suspect that you aircraft probably has got

"our" magnetos fitted!



But where I have a question is that your problem seems to occur before the

engine is really hot - i.e. on take-off. Of course it will have been warmed

up and able to accept full power, but my experience of magneto coil issues

is that they do happen when the engine has been running for at least 20

minutes or so and heat has soaked right through the engine to the magnetos

and then to the coil.



In your case it does seem that the failure is shortly after take-off when

the magnetos are not going to be at their hottest.



But an obvious thing to do is to replicate the problem and then land and

check your sparking plugs - if one of the magnetos has not been working

correctly, this will be very obvious.



But if there's anything else, please come back to me on my direct email.



Richard



Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5 3LW



Tel:  [url=]+44 (0) 1544 340120[/url]

Fax: [url=]+44 (0) 1544 340129[/url]

www.russianaeros.com

--

Viperdoc

Joined: 19 Apr 2014
Posts: 484
Location: 08A

Posted: Fri Jun 22, 2018 7:24 pm Post subject: Engine running rough at high power settings?

They are not your standard round seals. The problem usually is not the seal itself. It is usually with engine runs over time the collar nut loosens allowing the an air leak leaning out the affected cylinder. Each year during my annual I check them to make sure they are tight. 

Doc



Sent from my iPad



 	  Quote: 	
		   On Jun 19, 2018, at 2:51 PM, apatton2 <apatton(at)alumni.princeton.edu> wrote:

 

 Re: induction system seals - are those o-ring type seals? I'm unfamiliar with them. Are the connections between the intake tubes and the case typically suspect, or is it the tubes and cylinders?

 

 --------

 Andrew Patton

 Yak-50

 San Francisco, CA

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=481015#481015

_________________
Viperdoc

romaine_richard(at)yahoo.
Guest

Posted: Sat Jun 23, 2018 3:44 am Post subject: Engine running rough at high power settings?

The other thing Iâ€™ve seen on my CJ is a hole worn thru the thin wall of the runner (combination of a few things worn/loose enough to put things in contact).



Rich 



Sent from my iPhone

apatton2

Joined: 17 Jan 2018
Posts: 27

Posted: Thu Jun 28, 2018 7:29 am Post subject: Re: Engine running rough at high power settings?

An update! Have been much delayed by work and other undesirable activities in my troubleshooting.



Yesterday I pulled cowl and checked tightness of intake tube connections as recommended. Visually inspected again and saw nothing out of ordinary. Recowled and started expecting, based on advice, to either find 1 bad mag at higher power settings on ground OR need to go fly and check.



Could not reproduce problem on ground (felt rough at 80% power, but the thing shakes like hell on the ground at 80% anyway, so this was inconclusive on all mag settings). Decided to go fly. Smooth application of throttle on takeoff resulted in...smooth operation. Raced overhead for 15min at 1500AGL in circles at both 82%/max throttle and 70%/6 potatoes. Smooth operation and nothing really out of the ordinary. Engine gauges normal. Inflight mag checks normal. Made sure to get CHT and oil temps up to the top of the green arcs.



Then departed local airport airspace. Climbed up to 10kft at max continuous (actually was hot day and saw oil temp hotter than I have ever seen it in this plane... ~72degC). Nothing. Did some acro, but mild G on the airplane (4-5). Nothing. Came home at cruise power. Nothing. You get the idea.



I don't know how to find this one anymore, but given that I had 1.2 of runtime on a hot (for Northern California) day, I'm guessing that a bad mag would have revealed itself? The intermittency of the problem, to me, suggests that it might be some sort of connectivity issue, but I already replaced the ignition harness leads.



Any thoughts welcome! Thanks for reading this far.

_________________
Andrew Patton
Yak-50
San Francisco, CA

Dawg

Joined: 19 May 2013
Posts: 355

Posted: Thu Jun 28, 2018 10:58 am Post subject: Engine running rough at high power settings?

Never land.



 	  Quote: 	
		   On Jun 29, 2018, at 00:29, apatton2 <apatton(at)alumni.princeton.edu> wrote:

 

 

 

 An update! Have been much delayed by work and other undesirable activities in my troubleshooting.

 

 Yesterday I pulled cowl and checked tightness of intake tube connections as recommended. Visually inspected again and saw nothing out of ordinary. Recowled and started expecting, based on advice, to either find 1 bad mag at higher power settings on ground OR need to go fly and check.

 

 Could not reproduce problem on ground (felt rough at 80% power, but the thing shakes like hell on the ground at 80% anyway, so this was inconclusive on all mag settings). Decided to go fly. Smooth application of throttle on takeoff resulted in...smooth operation. Raced overhead for 15min at 1500AGL in circles at both 82%/max throttle and 70%/6 potatoes. Smooth operation and nothing really out of the ordinary. Engine gauges normal. Inflight mag checks normal. Made sure to get CHT and oil temps up to the top of the green arcs.

 

 Then departed local airport airspace. Climbed up to 10kft at max continuous (actually was hot day and saw oil temp hotter than I have ever seen it in this plane... ~72degC). Nothing. Did some acro, but mild G on the airplane (4-5). Nothing. Came home at cruise power. Nothing. You get the idea.

 

 I don't know how to find this one anymore, but given that I had 1.2 of runtime on a hot (for Northern California) day, I'm guessing that a bad mag would have revealed itself? The intermittency of the problem, to me, suggests that it might be some sort of connectivity issue, but I already replaced the ignition harness leads.

 

 Any thoughts welcome! Thanks for reading this far.

 

 --------

 Andrew Patton

 Yak-50

 San Francisco, CA

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=481253#481253

_________________
Dawg

Vic

Joined: 12 Aug 2008
Posts: 115
Location: Southern Bavaria

Posted: Thu Jun 28, 2018 2:59 pm Post subject: Re: Engine running rough at high power settings?

Hi Andrew,

may I suggest to check firmness of engine cowling brackets and cowling cushions ? I donÂ´t know much about your type but with our 18 T we had sudden vibrations for years for unknown reasons and never at expected moments. Finally I think I have found the problem with a very flexible cowling assembly that might shake with prop wash turbulence at rare times. The 18 T has flat and soft flanks of the cowling, unlike 52s or the like with circular front aspect, so less a problem with these. Just thinking . . . . 



     Vic

cjpilot710(at)aol.com
Guest

Posted: Fri Jun 29, 2018 3:57 am Post subject: Engine running rough at high power settings?

Andy, 

 

  Just keep your eye on it.  Just tweaking the tightness of intake tube gaskets even a little bit, may have cured your problem even if it didn't feel like much.  It might not have been just one tube either, and the M-14p (to me) seems a little sensitive to intake leaks.  Big engines like W1820s PW1830s will almost always get a leaky intake tube if it backfires several times.  Just enjoy and keep your ears open. 

  

 

  Jim "Pappy" Goolsby

 

 

  --

apatton2

Joined: 17 Jan 2018
Posts: 27

Posted: Sun Nov 04, 2018 5:06 pm Post subject: Re: Engine running rough at high power settings?

OK, here I am again with the same problem. Coming into the break today at home airport at full throttle / 82% rpm, all of a sudden had the same engine vibe/ roughness. Pulling throttle back 1/4 did nothing. Pulling prop control back to 70% completely eliminated it. I waited a couple seconds and moved prop back to 82%. No vibe anymore, even at that higher prop setting that was an issue just 10 sec prior.



Next time I am going to mag check it right away... it's one of those situations where you want to stop the vibe ASAP when it happens, though, so may be a bit too spring-loaded on that.



Dennis, in terms of the sticking valves... is this something that you can use a borescope to reveal? I have added MMO and camguard (at different times) to the oil as you recommended. Did not see an issue for awhile after that, but again this has been super intermittent.



Any thoughts welcome!

Andrew

_________________
Andrew Patton
Yak-50
San Francisco, CA

Vic

Joined: 12 Aug 2008
Posts: 115
Location: Southern Bavaria

Posted: Mon Nov 05, 2018 5:52 am Post subject: Re: Engine running rough at high power settings?

Hmm, still sounds like bad engine rubber mounts or loose engine cowling or cowling seats . . . 



     Vic

apatton2

Joined: 17 Jan 2018
Posts: 27

Posted: Sun Dec 02, 2018 9:56 pm Post subject: Re: Engine running rough at high power settings?

One quick new datapoint (this problem is notoriously hard to reproduce). Did have another occurrence just a few days ago. Mag checked and there was zero difference between sides.

_________________
Andrew Patton
Yak-50
San Francisco, CA

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