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cffd(at)pgrb.com
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 Posted: Mon Feb 25, 2008 3:21 pm Post subject: Rough running 2200 |
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1. Several flying hours ago my 2200 (solid lifters-#988) started running rough at full throttle (~3140 rpm) and a bit rough about 3000 rpm (95 total hours). The float bowl was running over. My float needle was the one with the weak spring so I put in a new float needle with the stronger spring. Now, no fuel running over, engine off with Facet fuel pump for several minutes.
2. Engine still is rough at high throttle, I thought it might be rich so I installed 4 EGT probes 120 mm from exhaust faces before changing any jets. My main jet is 255.
3. At 2800 rpm all 4 cylinders are 1200 F, a bit cool for this rpm, engine is smooth as silk.
4. At 3000 rpm number 3 (hottest) is 1275 F, number 2 (coolest) is 1200 F and engine is slightly rough.
5. At full throttle number 1 and 3 are 1300 F a bit high (2 is 1200, 4 is 1250), number 3 CHT is 250 F others about 225 F. One time I saw number 3 almost to 1375 F. Engine is really pretty rough.
6. If number 3 EGT probe was in error it would have been different from the others at 2800 rpm, but it wasn’t.
7. The throttle movement from 3000 rpm to full throttle is about 20% of the throw with little change in rpm. Number 3 EGT drops quickly after going from full throttle back to about 3000 rpm.
8. I just finished my condition inspection and the compression varied from about 71/80 (#4) to 63/80 (#3).
9. I have a 2 ¼" radiator hose (90 degree bend) going into the carb.
10. How can the EGT’s be so high at higher throttle settings with a 255 main jet?
And most important, what can be causing the rough engine?
Thanks,
Chuck D.
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info(at)usjabiru.com
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| Posted: Mon Feb 25, 2008 3:47 pm Post subject: Rough running 2200 |
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What happens when you apply carb heat or apply choke when it is running rough? Does it get better or worse?
Pete Krotje
Jabiru USA Sport Aircraft, LLC
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Chuck Deiterich
Sent: Monday, February 25, 2008 5:18 PM
To: Jab-list
Subject: Rough running 2200
1. Several flying hours ago my 2200 (solid lifters-#988) started running rough at full throttle (~3140 rpm) and a bit rough about 3000 rpm (95 total hours). The float bowl was running over. My float needle was the one with the weak spring so I put in a new float needle with the stronger spring. Now, no fuel running over, engine off with Facet fuel pump for several minutes.
2. Engine still is rough at high throttle, I thought it might be rich so I installed 4 EGT probes 120 mm from exhaust faces before changing any jets. My main jet is 255.
3. At 2800 rpm all 4 cylinders are 1200 F, a bit cool for this rpm, engine is smooth as silk.
4. At 3000 rpm number 3 (hottest) is 1275 F, number 2 (coolest) is 1200 F and engine is slightly rough.
5. At full throttle number 1 and 3 are 1300 F a bit high (2 is 1200, 4 is 1250), number 3 CHT is 250 F others about 225 F. One time I saw number 3 almost to 1375 F. Engine is really pretty rough.
6. If number 3 EGT probe was in error it would have been different from the others at 2800 rpm, but it wasn’t.
7. The throttle movement from 3000 rpm to full throttle is about 20% of the throw with little change in rpm. Number 3 EGT drops quickly after going from full throttle back to about 3000 rpm.
8. I just finished my condition inspection and the compression varied from about 71/80 (#4) to 63/80 (#3).
9. I have a 2 ¼" radiator hose (90 degree bend) going into the carb.
10. How can the EGT’s be so high at higher throttle settings with a 255 main jet?
And most important, what can be causing the rough engine?
Thanks,
Chuck D.
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Peter H
Joined: 20 Mar 2007
Posts: 197
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| Posted: Mon Feb 25, 2008 8:20 pm Post subject: Rough running 2200 |
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Chuck,
The needle valve seat usually leaks at anything above 2800 because the seat supplied is meant for gravity feed.
Also at the high throttle settings the fuel/air intake becomes uneven because of induction pulses in the small induction pipes collector which is less than 1/2L in capacity. I am working on a 3.5L intake manifold to solve my engine which is now fuel injected.
During development I found that EGT R was about 100degC greater than EGT L and was told that this is common, but when I increased the butterfly diameter EGT L became 100degC hotter than EGT R. I think the turbulence in that induction collector is disturbing fuel/air distribution and the effect is different at different RPM and worst at WOT.
When the fuel/air mix is out of balance the engine runs out of balance or slightly rough because the power strokes are not uniform. On one occasion I had the engine shake badly.
Peter H
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Chuck Deiterich
Sent: Tuesday, 26 February 2008 9:18 AM
To: Jab-list
Subject: Rough running 2200
1. Several flying hours ago my 2200 (solid lifters-#988) started running rough at full throttle (~3140 rpm) and a bit rough about 3000 rpm (95 total hours). The float bowl was running over. My float needle was the one with the weak spring so I put in a new float needle with the stronger spring. Now, no fuel running over, engine off with Facet fuel pump for several minutes.
2. Engine still is rough at high throttle, I thought it might be rich so I installed 4 EGT probes 120 mm from exhaust faces before changing any jets. My main jet is 255.
3. At 2800 rpm all 4 cylinders are 1200 F, a bit cool for this rpm, engine is smooth as silk.
4. At 3000 rpm number 3 (hottest) is 1275 F, number 2 (coolest) is 1200 F and engine is slightly rough.
5. At full throttle number 1 and 3 are 1300 F a bit high (2 is 1200, 4 is 1250), number 3 CHT is 250 F others about 225 F. One time I saw number 3 almost to 1375 F. Engine is really pretty rough.
6. If number 3 EGT probe was in error it would have been different from the others at 2800 rpm, but it wasn’t.
7. The throttle movement from 3000 rpm to full throttle is about 20% of the throw with little change in rpm. Number 3 EGT drops quickly after going from full throttle back to about 3000 rpm.
8. I just finished my condition inspection and the compression varied from about 71/80 (#4) to 63/80 (#3).
9. I have a 2 ¼" radiator hose (90 degree bend) going into the carb.
10. How can the EGT’s be so high at higher throttle settings with a 255 main jet?
And most important, what can be causing the rough engine?
Thanks,
Chuck D.
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[quote][b]
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cffd(at)pgrb.com
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| Posted: Tue Feb 26, 2008 1:22 pm Post subject: Rough running 2200 |
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Pete and Peter,
Thanks for the inputs. When the weather settles down I will try the carb
heat, choke and electric fuel pump too.
I will also try to smooth out the air to the carb.
Chuck
do not archive
| Quote: | Time: 03:47:50 PM PST US
From: "Jabiru USA" <info(at)usjabiru.com>
Subject: RE: Rough running 2200
What happens when you apply carb heat or apply choke when it is running
rough? Does it get better or worse?
Pete Krotje
Jabiru USA Sport Aircraft, LLC
_____
From: "Peter Harris" <peterjfharris(at)bigpond.com>
Subject: RE: Rough running 2200
Chuck,
The needle valve seat usually leaks at anything above 2800 because the
seat
supplied is meant for gravity feed.
Also at the high throttle settings the fuel/air intake becomes uneven
because of induction pulses in the small induction pipes collector which
is
less than 1/2L in capacity. I am working on a 3.5L intake manifold to
solve
my engine which is now fuel injected.
During development I found that EGT R was about 100degC greater than EGT
L
and was told that this is common, but when I increased the butterfly
diameter EGT L became 100degC hotter than EGT R. I think the turbulence
in
that induction collector is disturbing fuel/air distribution and the
effect
is different at different RPM and worst at WOT.
When the fuel/air mix is out of balance the engine runs out of balance
or
slightly rough because the power strokes are not uniform. On one
occasion I
had the engine shake badly.
Peter H
|
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Lynn Matteson
Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan
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| Posted: Tue Feb 26, 2008 2:35 pm Post subject: Rough running 2200 |
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Chuck-
Do you have the recommended 4" (at least ) of straight, smooth tubing
attached to the carb?
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/475+ hrs
On Feb 26, 2008, at 4:19 PM, Chuck Deiterich wrote:
| Quote: |
<cffd(at)pgrb.com>
Pete and Peter,
Thanks for the inputs. When the weather settles down I will try
the carb heat, choke and electric fuel pump too.
I will also try to smooth out the air to the carb.
Chuck
do not archive
> Time: 03:47:50 PM PST US
> From: "Jabiru USA" <info(at)usjabiru.com>
> Subject: RE: Rough running 2200
>
> What happens when you apply carb heat or apply choke when it is
> running
> rough? Does it get better or worse?
> Pete Krotje
>
> Jabiru USA Sport Aircraft, LLC
> _____
>
> From: "Peter Harris" <peterjfharris(at)bigpond.com>
> Subject: RE: Rough running 2200
>
> Chuck,
>
> The needle valve seat usually leaks at anything above 2800 because
> the
> seat
> supplied is meant for gravity feed.
>
> Also at the high throttle settings the fuel/air intake becomes uneven
> because of induction pulses in the small induction pipes collector
> which
> is
> less than 1/2L in capacity. I am working on a 3.5L intake manifold to
> solve
> my engine which is now fuel injected.
>
> During development I found that EGT R was about 100degC greater
> than EGT
> L
> and was told that this is common, but when I increased the butterfly
> diameter EGT L became 100degC hotter than EGT R. I think the
> turbulence
> in
> that induction collector is disturbing fuel/air distribution and the
> effect
> is different at different RPM and worst at WOT.
>
> When the fuel/air mix is out of balance the engine runs out of
> balance
> or
> slightly rough because the power strokes are not uniform. On one
> occasion I
> had the engine shake badly.
>
> Peter H
|
| | - 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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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM |
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