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Rough Running

 
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hgmckay



Joined: 23 May 2006
Posts: 397

PostPosted: Thu Jul 17, 2014 5:08 am    Post subject: Rough Running Reply with quote

I have a 912 UL engine (671 hours TSN) on my Allegro 2000 E-LSA. I routinely changed the 8 plugs yesterday. Have done this numerous times without any problem. Immediately upon starting the engine it was difficult to start and when it finally did start it ran with difficulty and was very very rough especially around 2000 to 2500 rpm (almost wanted to jump out of the engine mounts). I stopped the engine immediately and rechecked all that I had done. Everything appeared to be correct. The wires were connected correctly and were tight on the plugs themselves. The engine was running fine before I changed the plugs. Nothing was done except to pull off the plug caps, remove the old plugs, install new NG DCPR7E plugs with small amount of heat transfer compound on threads, new electrode gap was 0.030, torqued to 177 in.lb, and plug caps reinstalled tight.

Removing the plug caps from the plugs is difficult because of how tight they fit. The caps have to be “wiggled” some to get them to begin to release to be pulled off. Since I have done this routinely for a number of times (6 times since new) I thought I may have damaged one of the plug caps. The problem is clearly an engine ignition problem and the only place where the plug wires have been handled or manipulated is at the plug caps where I have to physically pull off the caps to remove and replace the plugs. If I have damaged the wire/cap connection inside the cap how do I find this out? How do I check the individual plug wires for the proper resistance since one end of each wire is connected to the solid state ignition modules? I notice that the Rotax Maintenance Manual states that heat conduction compound can lead to ignition problems and the spark plug seat and threads in the cylinder should be cleaned to remove any residue of the heat conduction compound. How do you clean the seat and threads in the cylinder? Remember, I have done nothing but replaced the plugs. Any help and or advice would be appreciated.

Hugh G. McKay III, P.E.
Senior Consultant
Worldwide Engineering Inc.
4090 North NC Hwy. 16
Denver, NC 28037

Allegro 2000
N661WW
Rotax 912 UL
671 hours

Ph. 704-661-8271
Fax 704-483-5466
email hgmckay(at)bellsouth.net
http://www.wwegeo.com


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John Hauck



Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

PostPosted: Thu Jul 17, 2014 5:34 am    Post subject: Rough Running Reply with quote

First, I would regap plugs to .025.

Second, double check that spark plug wires are on the correct cylinders.

If the engine was running normally before you changed plugs, then the problem is something that was changed by you during the plug replacement.

john h
mkIII
Thermopolis, WY

From: owner-rotaxengines-list-server(at)matronics.com [mailto:owner-rotaxengines-list-server(at)matronics.com] On Behalf Of Hugh McKay
Sent: Thursday, July 17, 2014 7:08 AM
To: Rotax Engines
Subject: Rough Running

I have a 912 UL engine (671 hours TSN) on my Allegro 2000 E-LSA. I routinely changed the 8 plugs yesterday. Have done this numerous times without any problem. Immediately upon starting the engine it was difficult to start and when it finally did start it ran with difficulty and was very very rough especially around 2000 to 2500 rpm (almost wanted to jump out of the engine mounts). I stopped the engine immediately and rechecked all that I had done. Everything appeared to be correct. The wires were connected correctly and were tight on the plugs themselves. The engine was running fine before I changed the plugs. Nothing was done except to pull off the plug caps, remove the old plugs, install new NG DCPR7E plugs with small amount of heat transfer compound on threads, new electrode gap was 0.030, torqued to 177 in.lb, and plug caps reinstalled tight.



Removing the plug caps from the plugs is difficult because of how tight they fit. The caps have to be “wiggled” some to get them to begin to release to be pulled off. Since I have done this routinely for a number of times (6 times since new) I thought I may have damaged one of the plug caps. The problem is clearly an engine ignition problem and the only place where the plug wires have been handled or manipulated is at the plug caps where I have to physically pull off the caps to remove and replace the plugs. If I have damaged the wire/cap connection inside the cap how do I find this out? How do I check the individual plug wires for the proper resistance since one end of each wire is connected to the solid state ignition modules? I notice that the Rotax Maintenance Manual states that heat conduction compound can lead to ignition problems and the spark plug seat and threads in the cylinder should be cleaned to remove any residue of the heat conduction compound. How do you clean the seat and threads in the cylinder? Remember, I have done nothing but replaced the plugs. Any help and or advice would be appreciated.



Hugh G. McKay III, P.E.
Senior Consultant
Worldwide Engineering Inc.
4090 North NC Hwy. 16
Denver, NC 28037



Allegro 2000

N661WW

Rotax 912 UL

671 hours

Ph. 704-661-8271
Fax 704-483-5466
email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)
http://www.wwegeo.com

[quote][b]


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John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama
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PostPosted: Thu Jul 17, 2014 5:43 am    Post subject: Rough Running Reply with quote

Hi Hugh,

I would start by being really, really sure that you have the plug leads on the correct plugs.

Regards

Brian Davies

From: owner-rotaxengines-list-server(at)matronics.com [mailto:owner-rotaxengines-list-server(at)matronics.com] On Behalf Of Hugh McKay
Sent: 17 July 2014 14:08
To: Rotax Engines
Subject: Rough Running

I have a 912 UL engine (671 hours TSN) on my Allegro 2000 E-LSA. I routinely changed the 8 plugs yesterday. Have done this numerous times without any problem. Immediately upon starting the engine it was difficult to start and when it finally did start it ran with difficulty and was very very rough especially around 2000 to 2500 rpm (almost wanted to jump out of the engine mounts). I stopped the engine immediately and rechecked all that I had done. Everything appeared to be correct. The wires were connected correctly and were tight on the plugs themselves. The engine was running fine before I changed the plugs. Nothing was done except to pull off the plug caps, remove the old plugs, install new NG DCPR7E plugs with small amount of heat transfer compound on threads, new electrode gap was 0.030, torqued to 177 in.lb, and plug caps reinstalled tight.



Removing the plug caps from the plugs is difficult because of how tight they fit. The caps have to be “wiggled” some to get them to begin to release to be pulled off. Since I have done this routinely for a number of times (6 times since new) I thought I may have damaged one of the plug caps. The problem is clearly an engine ignition problem and the only place where the plug wires have been handled or manipulated is at the plug caps where I have to physically pull off the caps to remove and replace the plugs. If I have damaged the wire/cap connection inside the cap how do I find this out? How do I check the individual plug wires for the proper resistance since one end of each wire is connected to the solid state ignition modules? I notice that the Rotax Maintenance Manual states that heat conduction compound can lead to ignition problems and the spark plug seat and threads in the cylinder should be cleaned to remove any residue of the heat conduction compound. How do you clean the seat and threads in the cylinder? Remember, I have done nothing but replaced the plugs. Any help and or advice would be appreciated.



Hugh G. McKay III, P.E.
Senior Consultant
Worldwide Engineering Inc.
4090 North NC Hwy. 16
Denver, NC 28037



Allegro 2000

N661WW

Rotax 912 UL

671 hours

Ph. 704-661-8271
Fax 704-483-5466
email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)
http://www.wwegeo.com

[quote][b]


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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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max8992



Joined: 28 Jul 2011
Posts: 142

PostPosted: Thu Jul 17, 2014 6:03 am    Post subject: Rough Running Reply with quote

It looks very similar to what I had during last 50 hours maintenance (on my MCR 4S). It wasn’t the first visit I did and so I was very surprised to see how bad the engine was running after. And maybe I could still be there scratching my head (no hairs to pull out)  if someone didn’t came to show me that the lower wires were inverted on cylinders 2 and 4! Quite difficult to start, bad running on both mags and almost a shut down when running on “mag 1” or “mag2”.
So for me double check your wires (or triple or ask someone to do it for you, no shame!)

Max  Cointe
mcointe(at)free.fr (mcointe(at)free.fr)
F-PMLH Europa XS_TriGear
Kit #560-2003 912ULS/AirmasterAP332 520 hours

F-PLDJ Dyn’Aéro MCR 4S
Kit #27-2002 912ULSFR/MTProp MTV7A 1650 heures


De : owner-rotaxengines-list-server(at)matronics.com [mailto:owner-rotaxengines-list-server(at)matronics.com] De la part de Hugh McKay
Envoyé : jeudi 17 juillet 2014 15:08
À : Rotax Engines
Objet : Rough Running

I have a 912 UL engine (671 hours TSN) on my Allegro 2000 E-LSA. I routinely changed the 8 plugs yesterday. Have done this numerous times without any problem. Immediately upon starting the engine it was difficult to start and when it finally did start it ran with difficulty and was very very rough especially around 2000 to 2500 rpm (almost wanted to jump out of the engine mounts). I stopped the engine immediately and rechecked all that I had done. Everything appeared to be correct. The wires were connected correctly and were tight on the plugs themselves. The engine was running fine before I changed the plugs. Nothing was done except to pull off the plug caps, remove the old plugs, install new NG DCPR7E plugs with small amount of heat transfer compound on threads, new electrode gap was 0.030, torqued to 177 in.lb, and plug caps reinstalled tight.



Removing the plug caps from the plugs is difficult because of how tight they fit. The caps have to be “wiggled” some to get them to begin to release to be pulled off. Since I have done this routinely for a number of times (6 times since new) I thought I may have damaged one of the plug caps. The problem is clearly an engine ignition problem and the only place where the plug wires have been handled or manipulated is at the plug caps where I have to physically pull off the caps to remove and replace the plugs. If I have damaged the wire/cap connection inside the cap how do I find this out? How do I check the individual plug wires for the proper resistance since one end of each wire is connected to the solid state ignition modules? I notice that the Rotax Maintenance Manual states that heat conduction compound can lead to ignition problems and the spark plug seat and threads in the cylinder should be cleaned to remove any residue of the heat conduction compound. How do you clean the seat and threads in the cylinder? Remember, I have done nothing but replaced the plugs. Any help and or advice would be appreciated.



Hugh G. McKay III, P.E.
Senior Consultant
Worldwide Engineering Inc.
4090 North NC Hwy. 16
Denver, NC 28037



Allegro 2000

N661WW

Rotax 912 UL

671 hours

Ph. 704-661-8271
Fax 704-483-5466
email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)
http://www.wwegeo.com

[quote][b]


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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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Max8992
Europa XS #560 F-PMLH
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hgmckay



Joined: 23 May 2006
Posts: 397

PostPosted: Thu Jul 17, 2014 10:32 am    Post subject: Rough Running Reply with quote

When I replaced the plugs I did one at a time to make sure I connected the correct plug wire to the correct cylinder. Went Back and checked again today and the wires are correct. I also have the cylinder number marked on each valve cover, and each plug wire has a yellow band from the factory showing the number of the cylinder it goes to. Everything is correct. If the wires are connected correct, what would be my next step in finding the problem?

Hugh G. McKay III, P.E.
Senior Consultant
Worldwide Engineering Inc.
4090 North NC Hwy. 16
Denver, NC 28037

Ph. 704-661-8271
Fax 704-483-5466
email hgmckay(at)bellsouth.net
http://www.wwegeo.com

From: Max Cointe (Free) (mcointe(at)free.fr)
Sent: Thursday, July 17, 2014 10:02 AM
To: rotaxengines-list(at)matronics.com (rotaxengines-list(at)matronics.com)
Subject: RE: Rough Running



It looks very similar to what I had during last 50 hours maintenance (on my MCR 4S). It wasn’t the first visit I did and so I was very surprised to see how bad the engine was running after. And maybe I could still be there scratching my head (no hairs to pull out) if someone didn’t came to show me that the lower wires were inverted on cylinders 2 and 4! Quite difficult to start, bad running on both mags and almost a shut down when running on “mag 1” or “mag2”.
So for me double check your wires (or triple or ask someone to do it for you, no shame!)

Max Cointe
mcointe(at)free.fr (mcointe(at)free.fr)
F-PMLH Europa XS_TriGear
Kit #560-2003 912ULS/AirmasterAP332 520 hours

F-PLDJ Dyn’Aéro MCR 4S
Kit #27-2002 912ULSFR/MTProp MTV7A 1650 heures


De : owner-rotaxengines-list-server(at)matronics.com [mailto:owner-rotaxengines-list-server(at)matronics.com] De la part de Hugh McKay
Envoyé : jeudi 17 juillet 2014 15:08
À : Rotax Engines
Objet : Rough Running



I have a 912 UL engine (671 hours TSN) on my Allegro 2000 E-LSA. I routinely changed the 8 plugs yesterday. Have done this numerous times without any problem. Immediately upon starting the engine it was difficult to start and when it finally did start it ran with difficulty and was very very rough especially around 2000 to 2500 rpm (almost wanted to jump out of the engine mounts). I stopped the engine immediately and rechecked all that I had done. Everything appeared to be correct. The wires were connected correctly and were tight on the plugs themselves. The engine was running fine before I changed the plugs. Nothing was done except to pull off the plug caps, remove the old plugs, install new NG DCPR7E plugs with small amount of heat transfer compound on threads, new electrode gap was 0.030, torqued to 177 in.lb, and plug caps reinstalled tight.



Removing the plug caps from the plugs is difficult because of how tight they fit. The caps have to be “wiggled” some to get them to begin to release to be pulled off. Since I have done this routinely for a number of times (6 times since new) I thought I may have damaged one of the plug caps. The problem is clearly an engine ignition problem and the only place where the plug wires have been handled or manipulated is at the plug caps where I have to physically pull off the caps to remove and replace the plugs. If I have damaged the wire/cap connection inside the cap how do I find this out? How do I check the individual plug wires for the proper resistance since one end of each wire is connected to the solid state ignition modules? I notice that the Rotax Maintenance Manual states that heat conduction compound can lead to ignition problems and the spark plug seat and threads in the cylinder should be cleaned to remove any residue of the heat conduction compound. How do you clean the seat and threads in the cylinder? Remember, I have done nothing but replaced the plugs. Any help and or advice would be appreciated.



Hugh G. McKay III, P.E.
Senior Consultant
Worldwide Engineering Inc.
4090 North NC Hwy. 16
Denver, NC 28037



Allegro 2000

N661WW

Rotax 912 UL

671 hours

Ph. 704-661-8271
Fax 704-483-5466
email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)
http://www.wwegeo.com

[quote]

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lyleapgmc



Joined: 19 Feb 2014
Posts: 57

PostPosted: Thu Jul 17, 2014 11:45 am    Post subject: Rough Running Reply with quote

Put the old plugs back in. The problem stated with the new plugs. Many new products fail right out of the box. The consumer is now quality control.

On 7/17/2014 1:31 PM, Hugh McKay wrote:

[quote] When I replaced the plugs I did one at a time to make sure I connected the correct plug wire to the correct cylinder. Went Back and checked again today and the wires are correct. I also have the cylinder number marked on each valve cover, and each plug wire has a yellow band from the factory showing the number of the cylinder it goes to. Everything is correct. If the wires are connected correct, what would be my next step in finding the problem?

Hugh G. McKay III, P.E.
Senior Consultant
Worldwide Engineering Inc.
4090 North NC Hwy. 16
Denver, NC 28037

Ph. 704-661-8271
Fax 704-483-5466
email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)
http://www.wwegeo.com

From: Max Cointe (Free) (mcointe(at)free.fr)
Sent: Thursday, July 17, 2014 10:02 AM
To: rotaxengines-list(at)matronics.com (rotaxengines-list(at)matronics.com)
Subject: RE: Rough Running





It looks very similar to what I had during last 50 hours maintenance (on my MCR 4S). It wasn’t the first visit I did and so I was very surprised to see how bad the engine was running after. And maybe I could still be there scratching my head (no hairs to pull out) if someone didn’t came to show me that the lower wires were inverted on cylinders 2 and 4! Quite difficult to start, bad running on both mags and almost a shut down when running on “mag 1” or “mag2”.
So for me double check your wires (or triple or ask someone to do it for you, no shame!)

Max  Cointe
mcointe(at)free.fr (mcointe(at)free.fr)
F-PMLH Europa XS_TriGear
Kit #560-2003 912ULS/AirmasterAP332 520 hours

F-PLDJ Dyn’Aéro MCR 4S
Kit #27-2002 912ULSFR/MTProp MTV7A 1650 heures


De : owner-rotaxengines-list-server(at)matronics.com (owner-rotaxengines-list-server(at)matronics.com) [mailto:owner-rotaxengines-list-server(at)matronics.com (owner-rotaxengines-list-server(at)matronics.com)] De la part de Hugh McKay
Envoyé : jeudi 17 juillet 2014 15:08
À : Rotax Engines
Objet : Rough Running



I have a 912 UL engine (671 hours TSN) on my Allegro 2000 E-LSA. I routinely changed the 8 plugs yesterday. Have done this numerous times without any problem. Immediately upon starting the engine it was difficult to start and when it finally did start it ran with difficulty and was very very rough especially around 2000 to 2500 rpm (almost wanted to jump out of the engine mounts). I stopped the engine immediately and rechecked all that I had done. Everything appeared to be correct. The wires were connected correctly and were tight on the plugs themselves. The engine was running fine before I changed the plugs. Nothing was done except to pull off the plug caps, remove the old plugs, install new NG DCPR7E plugs with small amount of heat transfer compound on threads, new electrode gap was 0.030, torqued to 177 in.lb, and plug caps reinstalled tight.



Removing the plug caps from the plugs is difficult because of how tight they fit. The caps have to be “wiggled” some to get them to begin to release to be pulled off. Since I have done this routinely for a number of times (6 times since new) I thought I may have damaged one of the plug caps. The problem is clearly an engine ignition problem and the only place where the plug wires have been handled or manipulated is at the plug caps where I have to physically pull off the caps to remove and replace the plugs. If I have damaged the wire/cap connection inside the cap how do I find this out? How do I check the individual plug wires for the proper resistance since one end of each wire is connected to the solid state ignition modules? I notice that the Rotax Maintenance Manual states that heat conduction compound can lead to ignition problems and the spark plug seat and threads in the cylinder should be cleaned to remove any residue of the heat conduction compound. How do you clean the seat and threads in the cylinder? Remember, I have done nothing but replaced the plugs. Any help and or advice would be appreciated.



Hugh G. McKay III, P.E.
Senior Consultant
Worldwide Engineering Inc.
4090 North NC Hwy. 16
Denver, NC 28037



Allegro 2000

N661WW

Rotax 912 UL

671 hours

Ph. 704-661-8271
Fax 704-483-5466
email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)
http://www.wwegeo.com



Quote:


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href="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/c

--
Lyle

Sent from my Gateway E4610D desktop

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PostPosted: Thu Jul 17, 2014 12:03 pm    Post subject: Rough Running Reply with quote

On Thu, Jul 17, 2014 at 2:44 PM, Lyle Peterson <lyleap(at)centurylink.net (lyleap(at)centurylink.net)> wrote:
Quote:
Put the old plugs back in.  The problem stated with the new plugs.  Many new products fail right out of the box.  The consumer is now quality control.

On 7/17/2014 1:31 PM, Hugh McKay wrote:

Quote:
When I replaced the plugs I did one at a time to make sure I connected the correct plug wire to the correct cylinder. Went Back and checked again today and the wires are correct. I also have the cylinder number marked on each valve cover, and each plug wire has a yellow band from the factory showing the number of the cylinder it goes to. Everything is correct. If the wires are connected correct, what would be my next step in finding the problem?
 
Hugh G. McKay III, P.E.
Senior Consultant
Worldwide Engineering Inc.
4090 North NC Hwy. 16
Denver, NC 28037

Ph. [url=tel:704-661-8271]704-661-8271[/url]
Fax [url=tel:704-483-5466]704-483-5466[/url]
email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)
http://www.wwegeo.com
 
From: Max Cointe (Free) (mcointe(at)free.fr)
Sent: Thursday, July 17, 2014 10:02 AM
To: rotaxengines-list(at)matronics.com (rotaxengines-list(at)matronics.com)
Subject: RE: Rough Running


 


It looks very similar to what I had during last 50 hours maintenance (on my MCR 4S). It wasn’t the first visit I did and so I was very surprised to see how bad the engine was running after. And maybe I could still be there scratching my head (no hairs to pull out)  if someone didn’t came to show me that the lower wires were inverted on cylinders 2 and 4! Quite difficult to start, bad running on both mags and almost a shut down when running on “mag 1†or “mag2†.
So for me double check your wires (or triple or ask someone to do it for you, no shame!)
 
Max  Cointe
mcointe(at)free.fr (mcointe(at)free.fr)
F-PMLH Europa XS_TriGear
Kit #560-2003 912ULS/AirmasterAP332 520 hours
 
F-PLDJ Dyn’Aéro MCR 4S
Kit #27-2002 912ULSFR/MTProp MTV7A 1650 heures

 
De : owner-rotaxengines-list-server(at)matronics.com (owner-rotaxengines-list-server(at)matronics.com) [mailto:owner-rotaxengines-list-server(at)matronics.com (owner-rotaxengines-list-server(at)matronics.com)] De la part de Hugh McKay
Envoyé : jeudi 17 juillet 2014 15:08
À : Rotax Engines
Objet : Rough Running


 
I have a 912 UL engine (671 hours TSN) on my Allegro 2000 E-LSA. I routinely changed the 8 plugs yesterday. Have done this numerous times without any problem. Immediately upon starting the engine it was difficult to start and when it finally did start it ran with difficulty and was very very rough especially around 2000 to 2500 rpm (almost wanted to jump out of the engine mounts). I stopped the engine immediately and rechecked all that I had done. Everything appeared to be correct. The wires were connected correctly and were tight on the plugs themselves. The engine was running fine before I changed the plugs. Nothing was done except to pull off the plug caps, remove the old plugs, install new NG DCPR7E plugs with small amount of heat transfer compound on threads, new electrode gap was 0.030, torqued to 177 in.lb, and plug caps reinstalled tight.

 

Removing the plug caps from the plugs is difficult because of how tight they fit. The caps have to be “wiggled†some to get them to begin to release to be pulled off. Since I have done this routinely for a number of times (6 times since new) I thought I may have damaged one of the plug caps. The problem is clearly an engine ignition problem and the only place where the plug wires have been handled or manipulated is at the plug caps where I have to physically pull off the caps to remove and replace the plugs. If I have damaged the wire/cap connection inside the cap how do I find this out? How do I check the individual plug wires for the proper resistance since one end of each wire is connected to the solid state ignition modules? I notice that the Rotax Maintenance Manual states that heat conduction compound can lead to ignition problems and the spark plug seat and threads in the cylinder should be cleaned to remove any residue of the heat conduction compound. How do you clean the seat and threads in the cylinder? Remember, I have done nothing but replaced the plugs. Any help and or advice would be appreciated.

 

Hugh G. McKay III, P.E.
Senior Consultant
Worldwide Engineering Inc.
4090 North NC Hwy. 16
Denver, NC 28037

 

Allegro 2000

N661WW

Rotax 912 UL

671 hours

Ph. [url=tel:704-661-8271]704-661-8271[/url]
Fax [url=tel:704-483-5466]704-483-5466[/url]
email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)
http://www.wwegeo.com



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Quote:
--
Lyle

Sent from my Gateway E4610D desktop

Quote:


ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution



Hi Hugh
 
Download from here: http://contrails.free.fr/temp/9xx_heavy_maintenance_d05014.pdf the 912 heavy maintenance manual.
Go to section 74,scroll down to page 22, it will tell you what you are suppose to see in terms of electrical resistance on different reference points in the ignition system  . Check resistance from the internal of the plug connector  to ground on all spark plug connectors, any reading in the range of 10.5 to 12.7 K ohm is a good reading (I summarized the connector resistance with the high voltage coil resistance, the last two lines on page 22). If all is well in that area then I would say that you have one or more faulty spark plugs, or may be the method of gaping you used is wrong altogether? (replaced inch units with MM units?)
If you get some suspicious readings measuring the 8 connectors to ground, continue troubleshooting by separating the connectors from the wires, measuring the stand alone connector resistance  and then  the wire end to ground, compare to correct values as shown in page 22.
 
Good luck, tell us please what was the happy end of the story
Nati Niv
RANS S6S 912ULS
Illinois   
 


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JohnF



Joined: 13 May 2010
Posts: 124

PostPosted: Thu Jul 17, 2014 12:16 pm    Post subject: Rough Running Reply with quote

I had a similiar, but somewhat more gentle problem after a plug change recently. Roger Lee, at the Tucson Rotax Service Center, gave me a solution...when pulling the plug wires off it is easy to pull back the wire inside the cable....try this...remove the caps from the plug wires, and trim about 1/4-inch off the cable, then reinsert the top cap of the plug wire assembly back onto the plug top. If the wire had pulled back it would cause the problem you have.

Hope this helps.
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Roger Lee



Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

PostPosted: Thu Jul 17, 2014 3:05 pm    Post subject: Re: Rough Running Reply with quote

The Rotax plug gap spec is .023 to .027. The wide gap for hot months and the narrow gap for cold winter months. If you want to just use .025 it won't hurt a thing. Absolutely no anti seize on any Rotax plugs... It should be the silicone based heat sync paste. Do not let it get down on the tips or it will cause mis-firing. Keep the paste on the upper 1/2 - 2/3 of the top of the plug threads. Leave the bottom 1/2 1/3 clean threads.
If you yank a plug boot off too hard you may dislocate or pull the wire tip out of it's threaded anchor inside the boot. Always grab the plug boot and try not to be ham fisted. Just wiggle it back and forth as you pull.
Many have found that they swapped plug wires even though they thought they were right. Just double check.
If it shook this hard then it isn't just one plug wire or plug being an issue.

p.s.

It is possible that an ignition module is going bad. Check the mag drop. If it is 800+ then most likely a module and if it is 300 or less then it is something else.


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Dick Maddux



Joined: 24 Jun 2008
Posts: 516
Location: Milton, Fl

PostPosted: Fri Jul 18, 2014 5:47 am    Post subject: Rough Running Reply with quote

Hugh,
I had this happen to me on 2 occasions. The first one occurred when I reversed two of the plug wires when a friend walked into my hanger when I was working on the plane. I got distracted (won't do that again)
The second one happened when I put new plugs in the engine as you have. After much checking I finally removed the new plugs and "bomb" checked them in my friends Champion spark plug checker. I found that one of the new plugs would not fire when pressure was applied to it. I chucked that plug in the bin and installed another new plug(after checking it) Problem solved.

Dick Maddux
912UL
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rlborger(at)mac.com
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PostPosted: Fri Jul 18, 2014 6:40 am    Post subject: Rough Running Reply with quote

Hugh,

OK, let me add my 2 on the subject. Last year at annual condition inspection I replaced the plugs on my 914. Ran like a sewing machine before the annual. Ran rough as a cob after. All the plug wires in the right places. Investigated the ignition module wiring, OK. Played with balancing the carbs. Nothing helped. Pulled the new plugs and inspected them, one at a time. One of the new plugs had a cracked insulator between the center electrode and outer case. You could see it after the run because the crack was stained brown. Replaced that plug and the engine ran much better. Smoothed out beautifully when I went back and rebalanced the carbs.

Check all those new plugs. One or more could be bad. If you have the facilities, pressure (or bomb) check them as well. If all your plug wires go to the right place, I bet you have one or two bad plugs.

Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop (50 hrs).
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: 817-992-1117
rlborger(at)mac.com


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