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rpm(at)robertpmillerphd.c
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 Posted: Thu Aug 19, 2010 5:03 am Post subject: Ghost in the engine 2200A |
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Hi Y'all,
I've got an engine problem that has all the experts stumped, including those at US Jabiru. I'm grounded and heartbroken, and short of calling Click and Clack and playing Stump the Chump, don't know what to do. So if you can solve this, you'll earn my undying appreciation (which, plus a nickel, will get you....)
Here's a review of the situation so far.
The Problem:
Immediately after the annual inspection in March, the engine began running rough above about 2,650 rpm. It starts with a little roughness, and the longer it runs above that rpm the rougher it gets, and soon the rpm starts bouncing around wildly within a range of about 2,500 to 2,750. One of the cylinders will start cooling down in EGTs and CHTs. Which cylinder it is will change; it’s nearly always 2 or 4, sometimes 3, and rarely 1. When the power is reduced below about 2,650, the cool cylinder warms up and everything runs smoothly.
It seems like after every change, it runs a little bit better for a little while, but then reverts to the same problem. It’s interesting that I can run it for a while and have the problem be on one cylinder, then shut it down for 5 minutes and then start it again and have the problem be on another cylinder.
The following have resulted in no change:
L, R, or Both magnetos.
Carb heat On or Off.
Electric fuel pump On or Off.
Replaced rotors, distributor cap, spark plug wires, and sparkplugs.
New carburetor. (The only difference this made was that a couple EGTs ran too high.)
Inspections that were normal:
I’ve removed the carb and looked into the intake manifold but could see no obstructions or abnormalities.
There was no metal in the oil filter.
All the valve springs appear to have the same resistance when I push on them. The rocker arms all appear perfectly aligned when in the full up/out position. (since the problem bounces from cylinder to cylinder, valve seems unlikely..?) I also removed the air intake Scat hose and tried running it with carb intake open to the engine compartment (with both the old and new carb).
--
Bob Miller
[quote][b]
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Lynn Matteson
Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan
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| Posted: Thu Aug 19, 2010 5:27 am Post subject: Ghost in the engine 2200A |
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How many hours on the engine, and what serial number is it?
Hydraulics or solid lifters? Not that the answers will make any
difference, but it would be nice to know whether it's a new engine or
one of the older ones.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Sensenich 62"x46" Wood (summer)
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying...1040+ hrs (since 3-27-2006)
On Aug 19, 2010, at 8:55 AM, Bob Miller wrote:
| Quote: | Hi Y'all,
I've got an engine problem that has all the experts stumped,
including those at US Jabiru. I'm grounded and heartbroken, and
short of calling Click and Clack and playing Stump the Chump,
don't know what to do. So if you can solve this, you'll earn my
undying appreciation (which, plus a nickel, will get you....)
Here's a review of the situation so far.
The Problem:
Immediately after the annual inspection in March, the engine began
running rough above about 2,650 rpm. It starts with a little
roughness, and the longer it runs above that rpm the rougher it
gets, and soon the rpm starts bouncing around wildly within a range
of about 2,500 to 2,750. One of the cylinders will start cooling
down in EGTs and CHTs. Which cylinder it is will change; it’s
nearly always 2 or 4, sometimes 3, and rarely 1. When the power
is reduced below about 2,650, the cool cylinder warms up and
everything runs smoothly.
It seems like after every change, it runs a little bit better for a
little while, but then reverts to the same problem. It’s
interesting that I can run it for a while and have the problem be
on one cylinder, then shut it down for 5 minutes and then start it
again and have the problem be on another cylinder.
The following have resulted in no change:
L, R, or Both magnetos.
Carb heat On or Off.
Electric fuel pump On or Off.
Replaced rotors, distributor cap, spark plug wires, and sparkplugs.
New carburetor. (The only difference this made was that a couple
EGTs ran too high.)
Inspections that were normal:
I’ve removed the carb and looked into the intake manifold but could
see no obstructions or abnormalities.
There was no metal in the oil filter.
All the valve springs appear to have the same resistance when I
push on them. The rocker arms all appear perfectly aligned when
in the full up/out position. (since the problem bounces from
cylinder to cylinder, valve seems unlikely..?)
I also removed the air intake Scat hose and tried running it with
carb intake open to the engine compartment (with both the old and
new carb).
--
Bob Miller
============================================================ _-
============================================================ _-
contribution_-
============================================================
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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM |
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Rickey B.
Joined: 22 Mar 2008
Posts: 70
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| Posted: Thu Aug 19, 2010 5:40 am Post subject: Ghost in the engine 2200A |
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You stated you changed the rotor, cap, etc. Did you change, or does it even have, a capacitor? I have had big problems on smaller engines in the past because of a faulty capacitor.
Hope this helps. p.s….a nickel won’t buy one
Rick
Do not archive
Hi Y'all,
I've got an engine problem that has all the experts stumped, including those at US Jabiru. I'm grounded and heartbroken, and short of calling Click and Clack and playing Stump the Chump, don't know what to do. So if you can solve this, you'll earn my undying appreciation (which, plus a nickel, will get you....)
[quote] [b]
| | - The Matronics JabiruEngine-List Email Forum - | | | 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:
http://www.matronics.com/Navigator?JabiruEngine-List |
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mhubel
Joined: 05 Sep 2009
Posts: 141
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| Posted: Thu Aug 19, 2010 5:40 am Post subject: Ghost in the engine 2200A |
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Bob,
This sounds very similar to the problems I had with the Bing. There was nothing wrong with it as in being defective, it just does not like my aitframe. The Jabiru solution was to "straighten" the air intake but that was not possible. Very small and un-intended changes in the air intake path seem to have very large effects on the bing.
You can test this theory by disconnecting the air intake hose (and air box sampling line!) completely and letting the carb take in raw air. If that fixes it, the problem is the air intake path. Fixing it may not be practical as the same thing could happen again.
I gave up and now have a Rotec TBI-40. I am upgrading the mount and will have it finished in a couple of weeks. If this upgrade works I will post everything.
On 08/19/2010 8:55 AM, Bob Miller wrote: | Quote: | Hi Y'all,
I've got an engine problem that has all the experts stumped, including those at US Jabiru. I'm grounded and heartbroken, and short of calling Click and Clack and playing Stump the Chump, don't know what to do. So if you can solve this, you'll earn my undying appreciation (which, plus a nickel, will get you....)
Here's a review of the situation so far.
The Problem:
Immediately after the annual inspection in March, the engine began running rough above about 2,650 rpm. It starts with a little roughness, and the longer it runs above that rpm the rougher it gets, and soon the rpm starts bouncing around wildly within a range of about 2,500 to 2,750. One of the cylinders will start cooling down in EGTs and CHTs. Which cylinder it is will change; it’s nearly always 2 or 4, sometimes 3, and rarely 1. When the power is reduced below about 2,650, the cool cylinder warms up and everything runs smoothly.
It seems like after every change, it runs a little bit better for a little while, but then reverts to the same problem. It’s interesting that I can run it for a while and have the problem be on one cylinder, then shut it down for 5 minutes and then start it again and have the problem be on another cylinder.
The following have resulted in no change:
L, R, or Both magnetos.
Carb heat On or Off.
Electric fuel pump On or Off.
Replaced rotors, distributor cap, spark plug wires, and sparkplugs.
New carburetor. (The only difference this made was that a couple EGTs ran too high.)
Inspections that were normal:
I’ve removed the carb and looked into the intake manifold but could see no obstructions or abnormalities.
There was no metal in the oil filter.
All the valve springs appear to have the same resistance when I push on them. The rocker arms all appear perfectly aligned when in the full up/out position. (since the problem bounces from cylinder to cylinder, valve seems unlikely..?) I also removed the air intake Scat hose and tried running it with carb intake open to the engine compartment (with both the old and new carb).
--
Bob Miller
| Quote: |
href="http://www.matronics.com/Navigator?JabiruEngine-List">http://www.matronics.com/Navigator?JabiruEngine-List
href="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/contribution
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--
Mark Hubelbank
NorthEast Monitoring
2 Clock Tower Place
Suite 555
Maynard, MA, 01754 - USA
mhubel(at)nemon.com (mhubel(at)nemon.com)
978-443-3955 |
| | - The Matronics JabiruEngine-List Email Forum - | | | 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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_________________
Mark Hubelbank
N708HU
CH601XL
Jabiru 3300
Rotec TBI 40-3 carb
Sensenich ground adj prop.
240 hr TAF
Pictures at photo.hubbles.com |
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don.honabach(at)pcperfect
Guest
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| Posted: Thu Aug 19, 2010 8:53 am Post subject: Ghost in the engine 2200A |
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Bob,
I posted this on the other list as well for you, but I added a few more thoughts this morning that might be helpful.
.......
I would have sworn you bumped the intake house during the annual as it sounded like turbulent air going into the carb which would have also made sense considering the random cylinders temps as the hose tends to flex and move a bit each test/RPM setting as the engine vibrates and moves under different loads/settings.
I didn't see anything in your message about fuel testing beyond electric fuel pump on/off. Is it possible the mechanical fuel pump is bad/going bad (I'm assuming the 2200 has a mechanical fuel pump as my 3300A does?) or there is a restriction in your fuel lines (new filter? mini clog?). Might be worth it to setup a temporary gravity feed setup that goes direct to the carb (and/or into the mechanical fuel pump) so you can bypass fuel line related issues. The roughness at higher RPMs for me has always been air related, but lack of fuel I would think would cause the same symptoms you've described
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naftalih(at)hotmail.com
Guest
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| Posted: Wed Aug 25, 2010 12:59 pm Post subject: Ghost in the engine 2200A |
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Try the following:
1. Adjust the butterfly to be about 5 deg. unparallel at WOT. That will create a vortex that might equalize the mixture distribution.
2. Tilt the carb about 5 deg. with the prop rotation. That might help in equalizing R & L cyl.
Good luck!
From: don.honabach(at)pcperfect.com
To: jabiruengine-list(at)matronics.com
Subject: RE: Ghost in the engine 2200A
Date: Thu, 19 Aug 2010 16:47:51 +0000
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Bob,
I posted this on the other list as well for you, but I added a few more thoughts this morning that might be helpful.
……..
I would have sworn you bumped the intake house during the annual as it sounded like turbulent air going into the carb which would have also made sense considering the random cylinders temps as the hose tends to flex and move a bit each test/RPM setting as the engine vibrates and moves under different loads/settings.
I didn't see anything in your message about fuel testing beyond electric fuel pump on/off. Is it possible the mechanical fuel pump is bad/going bad (I'm assuming the 2200 has a mechanical fuel pump as my 3300A does?) or there is a restriction in your fuel lines (new filter? mini clog?). Might be worth it to setup a temporary gravity feed setup that goes direct to the carb (and/or into the mechanical fuel pump) so you can bypass fuel line related issues. The roughness at higher RPMs for me has always been air related, but lack of fuel I would think would cause the same symptoms you’ve described.
By the way, you mentioned that the one of the cylinders starts to cool down when running rough, while I’m not an expert by any means, this would seem to indicate that you are running rich at higher RPMs which makes me wonder even more about the fuel pump/fuel hose setup going into the carb. The cylinder that cools down is the one that just happens to get the most fuel which will tend to change based on the air intake flows. This also seems to jive with your comments as most carbs are a bit unbalanced and favor either the left or right bank of cylinders which will get just a tad bit more air … which seems to align with your 2/4 being the usual culprits.
You might also want to check the air/fuel manifold if that is the correct term for it – I haven’t looked closely at this area, but any small leaks might be okay at lower RPMs, but at higher RPMs could cause these same sort of troubles.
I’m assuming you re-tighten the head screws on the cylinders during the annual – did you have any noticeable issues there? Are you 100% sure that all the head bolts are 100% at the specified torque values – you got the middle ‘hidden’ screw as well?
Good luck and please share when you find out the cause.
Don Honabach
P.S. When you tested with the scat house disconnected from the carb, did you also remove the air sense tube on the carb as well? If not, you definitely will want to re-do that test with the air sense tube and scat disconnected. When troubleshooting my roughness at high RPM, I actually flew this way (carb totally open to cowling) and quickly determined that my issue was turbulent air in the intake which took a ton of little tweaks to smooth out. Also, did you plug up the air-intake on your cowling when doing the test. If not, you may have had pressured type air shooting into the cowling during the test (even during ground testing) and if it was anywhere near the carb it would have messed things up for you at higher RPMs as the Bing carb needs smooth air to function properly at high RPMs.
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Bob Miller
Sent: Thursday, August 19, 2010 5:56 AM
To: jabiruengine-list(at)matronics.com
Subject: JabiruEngine-List: Ghost in the engine 2200A
Hi Y'all,
I've got an engine problem that has all the experts stumped, including those at US Jabiru. I'm grounded and heartbroken, and short of calling Click and Clack and playing Stump the Chump, don't know what to do. So if you can solve this, you'll earn my undying appreciation (which, plus a nickel, will get you....)
Here's a review of the situation so far.
The Problem:
Immediately after the annual inspection in March, the engine began running rough above about 2,650 rpm. It starts with a little roughness, and the longer it runs above that rpm the rougher it gets, and soon the rpm starts bouncing around wildly within a range of about 2,500 to 2,750. One of the cylinders will start cooling down in EGTs and CHTs. Which cylinder it is will change; it’s nearly always 2 or 4, sometimes 3, and rarely 1. When the power is reduced below about 2,650, the cool cylinder warms up and everything runs smoothly.
It seems like after every change, it runs a little bit better for a little while, but then reverts to the same problem. It’s interesting that I can run it for a while and have the problem be on one cylinder, then shut it down for 5 minutes and then start it again and have the problem be on another cylinder.
The following have resulted in no change:
L, R, or Both magnetos.
Carb heat On or Off.
Electric fuel pump On or Off.
Replaced rotors, distributor cap, spark plug wires, and sparkplugs.
New carburetor. (The only difference this made was that a couple EGTs ran too high.)
Inspections that were normal:
I’ve removed the carb and looked into the intake manifold but could see no obstructions or abnormalities.
There was no metal in the oil filter.
All the valve springs appear to have the same resistance when I push on them. The rocker arms all appear perfectly aligned when in the full up/out position. (since the problem bounces from cylinder to cylinder, valve seems unlikely..?)
I also removed the air intake Scat hose and tried running it with carb intake open to the engine compartment (with both the old and new carb).
--
Bob Miller
<pre; - The JabiruEngine-List Eive Search & Download, 7-Day Browse, Chat, FAQ,[/b]http://www.matronics.com/Nav================[/b] | Quote: | | < Same great content also available via the Web Forums![/b] |
="http://forums.matronics.com">http://forums.matronics.combsp; - List Contribution Web Site -<o:pnbsp; -Matt Dralle, Listp://www.matronics.com/contribution">http://www.matronics.com/contribution[/b][quote]
-List" target=_blank>http://www.matronics.com/Navigator?JabiruEngine-List
ttp://forums.matronics.com
=_blank>http://www.matronics.com/contribution
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