Today's Message Index:
----------------------
1. 04:48 AM - Re: Engine combustion troubleshooting concepts (Ralph E. Capen)
2. 06:11 AM - Re: Engine combustion troubleshooting concepts (Kelly McMullen)
3. 06:25 AM - Re: Engine combustion troubleshooting concepts (Ralph E. Capen)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Engine combustion troubleshooting concepts |
Thanks.
This was only one cylinder, the EGT only went up (enough to catch my attention
- not red-line).
I have already pulled both plugs - the lower one was wet which may not mean anything.
Neither of them looked abnormal - cleaned and reinstalled.
-----Original Message-----
From: Shannon Miller
Sent: Dec 3, 2012 7:21 PM
Subject: Re: RV-List: Engine combustion troubleshooting concepts
I'm no expert, but I can share my own understanding. See below.
On Mon, Dec 3, 2012 at 2:33 PM, Ralph E. Capen <recapen@earthlink.net> wrote:
Re-breaking in my engine after prop-strike by hangar door induced by tornado.
Considering the engine already had 160+ hours on it - I know how it was running
for a while.
I have one cylinder running not like the others. Before I tell what is happening,
I want to make sure I understand/remember the basic concepts.
EGT-only elevated - CHT reduced...unburned fuel going out exhaust and burning on
the way out - plug not firing
Right. Possibly some sort of spark plug problem. Could be a fouled plug or disconnected/broken
plug wire. Consider a mag check (even if you're only seeing this
in flight -- just do it at a safe altitude and within gliding distance to a
safe landing spot) to identify the plug/wire; if the engine quits, pull the throttle
to idle before switching off the bad mag to avoid backfiring.
EGT-only elevated - ...unburned fuel going out exhaust and burning on the way out
- plug not firing completely
Agreed. Same possible causes as above.
CHT-only elevated...not enough cooling air
Or insufficient fuel flow, power too high for the air flow, mixture too lean, or
RPM too low for the power setting. Possible in-flight solutions: lower nose
to increase airspeed, open cowl flaps if you have them, enrichen the mixture (confirm
that you're rich of peak by noting a decrease in EGT's as you enrichen
the mixture), reduce power (MP), increase prop RPM. Now if it's just one cylinder,
I would guess it's either some sort of baffling issue or fuel flow issue
to that cylinder.
EGT and CHT elevated...lean mixture - air leak
Agree, or possible magneto/ignition problem if it's all cylinders -- a mag check
would identify which mag/ignition source. If it's just one cylinder, it could
be a partially clogged fuel injector: go full rich mixture and momentarily turn
on the boost pump -- it might dislodge the clog!
Refresh my memory here.
I assume you're talking only "somewhat" elevated EGT and CHT values, and not values
which are "sky high" which could indicate detonation or pre-ignition and
ultimate catastrophic engine failure!
That's all I can offer. No warranty, but I hope it helps!
--Shannon
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Engine combustion troubleshooting concepts |
Only two items will cause a single cylinder EGT to rise significantly.
Either one plug stopped firing, or an induction leak developed. Single
spark instead of two plugs firing will cause 50-150 degree EGT rise. So
will a loose intake tube or gasket.
On 12/4/2012 5:47 AM, Ralph E. Capen wrote:
>
> Thanks.
>
> This was only one cylinder, the EGT only went up (enough to catch my attention
- not red-line).
>
> I have already pulled both plugs - the lower one was wet which may not mean anything.
Neither of them looked abnormal - cleaned and reinstalled.
>
>
> -----Original Message-----
>
> From: Shannon Miller
>
> Sent: Dec 3, 2012 7:21 PM
>
> To: "rv-list@matronics.com"
>
> Subject: Re: RV-List: Engine combustion troubleshooting concepts
>
>
> I'm no expert, but I can share my own understanding. See below.
>
> On Mon, Dec 3, 2012 at 2:33 PM, Ralph E. Capen <recapen@earthlink.net> wrote:
>
> Re-breaking in my engine after prop-strike by hangar door induced by tornado.
>
>
> Considering the engine already had 160+ hours on it - I know how it was running
for a while.
>
>
> I have one cylinder running not like the others. Before I tell what is happening,
I want to make sure I understand/remember the basic concepts.
>
>
> EGT-only elevated - CHT reduced...unburned fuel going out exhaust and burning
on the way out - plug not firing
>
> Right. Possibly some sort of spark plug problem. Could be a fouled plug or disconnected/broken
plug wire. Consider a mag check (even if you're only seeing
this in flight -- just do it at a safe altitude and within gliding distance to
a safe landing spot) to identify the plug/wire; if the engine quits, pull the
throttle to idle before switching off the bad mag to avoid backfiring.
>
> EGT-only elevated - ...unburned fuel going out exhaust and burning on the way
out - plug not firing completely
>
> Agreed. Same possible causes as above.
>
> CHT-only elevated...not enough cooling air
>
> Or insufficient fuel flow, power too high for the air flow, mixture too lean,
or RPM too low for the power setting. Possible in-flight solutions: lower nose
to increase airspeed, open cowl flaps if you have them, enrichen the mixture
(confirm that you're rich of peak by noting a decrease in EGT's as you enrichen
the mixture), reduce power (MP), increase prop RPM. Now if it's just one cylinder,
I would guess it's either some sort of baffling issue or fuel flow issue
to that cylinder.
>
> EGT and CHT elevated...lean mixture - air leak
>
> Agree, or possible magneto/ignition problem if it's all cylinders -- a mag check
would identify which mag/ignition source. If it's just one cylinder, it could
be a partially clogged fuel injector: go full rich mixture and momentarily
turn on the boost pump -- it might dislodge the clog!
>
>
> Refresh my memory here.
> I assume you're talking only "somewhat" elevated EGT and CHT values, and not
values which are "sky high" which could indicate detonation or pre-ignition and
ultimate catastrophic engine failure!
>
> That's all I can offer. No warranty, but I hope it helps!
> --Shannon
>
>
-----
No virus found in this message.
Checked by AVG - www.avg.com
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Engine combustion troubleshooting concepts |
Thanks - I'll keep looking for an induction leak.
Already contemplating moving my MAP sensor port from that cylinder to the one in
front of it.
-----Original Message-----
>From: Kelly McMullen <kellym@aviating.com>
>Sent: Dec 4, 2012 9:10 AM
>To: rv-list@matronics.com
>Subject: Re: RV-List: Engine combustion troubleshooting concepts
>
>
>Only two items will cause a single cylinder EGT to rise significantly.
>Either one plug stopped firing, or an induction leak developed. Single
>spark instead of two plugs firing will cause 50-150 degree EGT rise. So
>will a loose intake tube or gasket.
>
>On 12/4/2012 5:47 AM, Ralph E. Capen wrote:
>>
>> Thanks.
>>
>> This was only one cylinder, the EGT only went up (enough to catch my attention
- not red-line).
>>
>> I have already pulled both plugs - the lower one was wet which may not mean
anything. Neither of them looked abnormal - cleaned and reinstalled.
>>
>>
>> -----Original Message-----
>>
>> From: Shannon Miller
>>
>> Sent: Dec 3, 2012 7:21 PM
>>
>> To: "rv-list@matronics.com"
>>
>> Subject: Re: RV-List: Engine combustion troubleshooting concepts
>>
>>
>>
>> I'm no expert, but I can share my own understanding. See below.
>>
>> On Mon, Dec 3, 2012 at 2:33 PM, Ralph E. Capen <recapen@earthlink.net> wrote:
>>
>> Re-breaking in my engine after prop-strike by hangar door induced by tornado.
>>
>>
>>
>> Considering the engine already had 160+ hours on it - I know how it was running
for a while.
>>
>>
>>
>> I have one cylinder running not like the others. Before I tell what is happening,
I want to make sure I understand/remember the basic concepts.
>>
>>
>>
>> EGT-only elevated - CHT reduced...unburned fuel going out exhaust and burning
on the way out - plug not firing
>>
>> Right. Possibly some sort of spark plug problem. Could be a fouled plug or disconnected/broken
plug wire. Consider a mag check (even if you're only seeing
this in flight -- just do it at a safe altitude and within gliding distance to
a safe landing spot) to identify the plug/wire; if the engine quits, pull the
throttle to idle before switching off the bad mag to avoid backfiring.
>>
>> EGT-only elevated - ...unburned fuel going out exhaust and burning on the way
out - plug not firing completely
>>
>> Agreed. Same possible causes as above.
>>
>> CHT-only elevated...not enough cooling air
>>
>> Or insufficient fuel flow, power too high for the air flow, mixture too lean,
or RPM too low for the power setting. Possible in-flight solutions: lower nose
to increase airspeed, open cowl flaps if you have them, enrichen the mixture
(confirm that you're rich of peak by noting a decrease in EGT's as you enrichen
the mixture), reduce power (MP), increase prop RPM. Now if it's just one cylinder,
I would guess it's either some sort of baffling issue or fuel flow issue
to that cylinder.
>>
>> EGT and CHT elevated...lean mixture - air leak
>>
>> Agree, or possible magneto/ignition problem if it's all cylinders -- a mag check
would identify which mag/ignition source. If it's just one cylinder, it could
be a partially clogged fuel injector: go full rich mixture and momentarily
turn on the boost pump -- it might dislodge the clog!
>>
>>
>>
>>
>> Refresh my memory here.
>> I assume you're talking only "somewhat" elevated EGT and CHT values, and not
values which are "sky high" which could indicate detonation or pre-ignition and
ultimate catastrophic engine failure!
>>
>> That's all I can offer. No warranty, but I hope it helps!
>> --Shannon
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>-----
>No virus found in this message.
>Checked by AVG - www.avg.com
>
>
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|