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Help! 3300 rough running puzzle. [SEC=UNCLASSIFIED]

 
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ian.sweeting(at)defence.g
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PostPosted: Tue Jun 07, 2011 2:25 pm    Post subject: Help! 3300 rough running puzzle. [SEC=UNCLASSIFIED] Reply with quote
UNCLASSIFIED It does sound like mixture.

Use in an aero engine is a little dangerous but an item such as a Gunson Colourtune spark plug will determine the temperature of the burn in that cylinder at particular RPM's and can be referenced to other cylinders.
The cause is another matter. You may find you have a significant variation of mixtures.

I do think that I read that previous Jab installations had this issue with variations/pooling.

Would not it be nice to be able to see the fuel mist inside the plenum manifold at various RPM's on the ground and in flight.

From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Martin Hone
Sent: Wednesday, 8 June 2011 07:53
To: jabiruengine-list(at)matronics.com
Subject: Re: Help! 3300 rough running puzzle.

Given that the two plugs are fired by independant ignition sources, it does suggest mixture. Weird....
martin

On Wed, Jun 8, 2011 at 7:32 AM, j. davis <jd(at)lawsonimaging.ca (jd(at)lawsonimaging.ca)> wrote:
Quote:
--> JabiruEngine-List message posted by: "j. davis" <jd(at)lawsonimaging.ca (jd(at)lawsonimaging.ca)>

On 06/07/2011 04:45 PM, Martin Hone wrote:
Quote:
J, maybe these plugs have always been black and sooty and it is a parculiarity of your induction system.

mh1

Hmmm, maybe, but I think I would have noticed at plug change time. I always put all the plugs I remove into a
labeled plug holder board I fabricated and examine them for differences. Also, I can't imagine that the 3300 intake manifold
could be so selective that one particular cylinder's plugs are sooty/black while all other cylinders have light tan plugs!

I wonder if it's just a matter of time before those two plugs actually foul, and the rough, stumbling mag checks come back.
... except that that theory is repudiated by the first time I replaced those two sooty plugs with new plugs
and the rough running was there *instantly*.

So the question stands. What could cause either:

- a single cylinder of six to run so rich as to actually foul *both* plugs

or

- the two plugs of the single cylinder not to fire sufficiently to burn off the charge

...keeping in mind the trouble-shooting items I have already eliminated...

Thanks for the input!

Quote:
On Wed, Jun 8, 2011 at 4:26 AM, j. davis <jd(at)lawsonimaging.ca (jd(at)lawsonimaging.ca) <mailto:jd(at)lawsonimaging.ca (jd(at)lawsonimaging.ca)>> wrote:

--> JabiruEngine-List message posted by: "j. davis" <jd(at)lawsonimaging.ca (jd(at)lawsonimaging.ca)
<mailto:jd(at)lawsonimaging.ca (jd(at)lawsonimaging.ca)>>

On 06/07/2011 09:19 AM, Beckman, Rick wrote:

-->

J., you might want to replace the plug wire for that particular cylinder. Cheap
elimination.
OK, this is weird. I swapped number three's plug wires for number four's, just for
the heck of it.
Replaced the two sooty #3 cyl. plugs and went taxing. It felt smoother immediately,
and when I did the mag tests,
both sides acted normally, with a 10-20 rpm drop and no rough running!

Got back and pulled #3 plugs... black and sooty again. #4 plugs just fine.

So what just happened???

Obviously, the #3 plug wires weren’t bad (and why should they have been), they are
now firing the #4 cylinder just fine.

The stumbling and rough running disappeared. Why?

The two #3 plugs are still getting black and sooty, EGT and CHT temps for #3 still fine.
R.

Do not archive

*
*

-- Regards, J.

- Sonex #325 C-FJNJ, Jab 3300a, Prince P-Tip, Aerocarb
- former C-IGGY CH701 owner/builder, CH750 in progress
- see both (and more!) at http://cleco.ca

+-------------------------------+
| J. Davis, M.Sc. (comp sci) |
| email: jd at lawsonimaging.ca <http://lawsonimaging.ca> |
| *NIX consulting, SysAdmin |
| http://cleco.ca |
+-------------------------------+
I washed a sock. Then I put it in the dryer. When I took
it out, it was gone.
--- Steven Wright
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*
*


--
Regards, J.

- Sonex #325 C-FJNJ, Jab 3300a, Prince P-Tip, Aerocarb
- former C-IGGY CH701 owner/builder, CH750 in progress
- see both (and more!) at http://cleco.ca

+-------------------------------+
| J. Davis, M.Sc. (comp sci) |
| email: jd at lawsonimaging.ca |
| *NIX consulting, SysAdmin |
| http://cleco.ca |
+-------------------------------+
The sky is falling...no, I'm tipping over backwards.
--- Steven Wright
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ine-List" target="_blank">http://www.matronics.com/Navigator?JabiruEngine-List
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k">http://forums.matronics.com
===========
e -
-Matt Dralle, List Admin.
t="_blank">http://www.matronics.com/contribution
===========



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jd(at)lawsonimaging.ca
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PostPosted: Tue Jun 07, 2011 2:55 pm    Post subject: Help! 3300 rough running puzzle. [SEC=UNCLASSIFIED] Reply with quote
On 06/07/2011 06:22 PM, Sweeting, Ian MR wrote:
Quote:

*UNCLASSIFIED*

It does sound like mixture.
Use in an aero engine is a little dangerous but an item such as a Gunson Colourtune
spark plug will determine the temperature of the burn in that cylinder at particular
RPM's and can be referenced to other cylinders.
The cause is another matter. You may find you have a significant variation of mixtures.
I do think that I read that previous Jab installations had this issue with
variations/pooling.

Well, it is well known that the stock Jabiru manifold does not totally equally distribute
the charge to all cylinders,
resulting in some range of EGTs. But to single a *lone* cylinder out? Unlikely. And don't
forget, I've got over 100 hours
on this engine, and it's been just fine up to now and last fall, when it last flew. What
possibly could have changed in the induction circuit
to make just one cylinder run *rich*?

Makes no sense to me.

Quote:
Would not it be nice to be able to see the fuel mist inside the plenum manifold at
various RPM's on the ground and in flight.

Lynn should have that going before long Smile

Quote:


On 06/07/2011 04:45 PM, Martin Hone wrote:

J, maybe these plugs have always been black and sooty and it is a parculiarity
of your induction system.

mh1

Hmmm, maybe, but I think I would have noticed at plug change time. I always put all
the plugs I remove into a
labeled plug holder board I fabricated and examine them for differences. Also, I
can't imagine that the 3300 intake manifold
could be so selective that one particular cylinder's plugs are sooty/black while all
other cylinders have light tan plugs!

I wonder if it's just a matter of time before those two plugs actually foul, and the
rough, stumbling mag checks come back.
... except that that theory is repudiated by the first time I replaced those two
sooty plugs with new plugs
and the rough running was there *instantly*.

So the question stands. What could cause either:

- a single cylinder of six to run so rich as to actually foul *both* plugs

or

- the two plugs of the single cylinder not to fire sufficiently to burn off the charge

...keeping in mind the trouble-shooting items I have already eliminated...

Thanks for the input!

--

Regards, J.

- Sonex #325 C-FJNJ, Jab 3300a, Prince P-Tip, Aerocarb
- former C-IGGY CH701 owner/builder, CH750 in progress
- see both (and more!) at http://cleco.ca

+-------------------------------+
| J. Davis, M.Sc. (comp sci) |
| email: jd at lawsonimaging.ca |
| *NIX consulting, SysAdmin |
| http://cleco.ca |
+-------------------------------+
Last night the power went out. Good thing my camera had a
flash...I took 65 pictures of myself making a sandwich...My
neighbors thought it was lightning in my house, so they
called the cops.
--- Steven Wright

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