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Help me solve engine power loss

 
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speedy11(at)aol.com
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PostPosted: Fri Aug 03, 2012 5:58 pm    Post subject: Help me solve engine power loss Reply with quote

Engine gurus,
I have a problem with my engine that has me stumped. Maybe someone has
seen this situation before or has an idea for resolution.
I have a Barrett IO-390 (essentially same as IO-360) that began missing
and losing power in June. I tracked down several "problems" which the
solution to I thought would solve the power loss. I found one spark
plug that seemed to be a problem. Replaced all plugs and tested them
before installation. Problem still there. Checked resistance in
harness. All good. Replaced harness anyway. Problem still there.
Sent P Mags back to factory for overhaul. Essentially have new P Mags
now. Problem still there. Cleaned injectors and flow tested. Flows
all equal. Cleaned fuel filter - nothing there. There is no air
filter when I run ram air, so nothing to inhibit air flow. I checked
the sniffle valve but no leak there.
On takeoff roll there seems to be slightly less power, but the power
loss is more noticeable (approx 20% loss) once airborne. At pattern
altitude with reduced power the engine runs ok. But as I add throttle
(high RPM on prop) the engine loses power as if it is loading up. The
EGTs and CHTs are normal. The RPM and MP are normal.
So, there you go. Any ideas?
Stan Sutterfield
RV-8A. Port Orange, FL


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tim2542(at)sbcglobal.net
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PostPosted: Fri Aug 03, 2012 6:22 pm    Post subject: Help me solve engine power loss Reply with quote

Well you have covered about everything except the engine. You need to start troubleshooting by knowing the engine is mechanically sound. Do a leak down test and check the valve guides for wear. Next check the oil filter for camshaft/lifter filings. Loose intake pipes in the sump or intake leaks of any kind is another possibility.
You say it's missing, that should present on the egt's. Can you download data from an EFIS? If its sporadic it will be difficult to see on an analog gauge unless you can see second by second data from a data dump onto excel. I know GRT and Garmin do this. Dynon won't.
Good luck, Tim

Sent from my iPad

On Aug 3, 2012, at 6:55 PM, speedy11(at)aol.com wrote:

Quote:


Engine gurus,
I have a problem with my engine that has me stumped. Maybe someone has seen this situation before or has an idea for resolution.
I have a Barrett IO-390 (essentially same as IO-360) that began missing and losing power in June. I tracked down several "problems" which the solution to I thought would solve the power loss. I found one spark plug that seemed to be a problem. Replaced all plugs and tested them before installation. Problem still there. Checked resistance in harness. All good. Replaced harness anyway. Problem still there. Sent P Mags back to factory for overhaul. Essentially have new P Mags now. Problem still there. Cleaned injectors and flow tested. Flows all equal. Cleaned fuel filter - nothing there. There is no air filter when I run ram air, so nothing to inhibit air flow. I checked the sniffle valve but no leak there.
On takeoff roll there seems to be slightly less power, but the power loss is more noticeable (approx 20% loss) once airborne. At pattern altitude with reduced power the engine runs ok. But as I add throttle (high RPM on prop) the engine loses power as if it is loading up. The EGTs and CHTs are normal. The RPM and MP are normal.
So, there you go. Any ideas?
Stan Sutterfield
RV-8A. Port Orange, FL









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Kelly McMullen



Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

PostPosted: Fri Aug 03, 2012 9:29 pm    Post subject: Help me solve engine power loss Reply with quote

Check the resistance on each spark plug between the inside of barrel
and the center electrode. Should be around 1000 ohms new, less than
5000 used. One plug breaking down or leaking spark to ground could
cause what you see.
Talk to Allan at Barrett, he is pretty sharp.
Check muffler for loose flame tube partially blocking exhaust. Check
for valve wobble/sticking. Just on a hunch, try setting timing to 20
degrees instead of 25.

On Fri, Aug 3, 2012 at 6:55 PM, <speedy11(at)aol.com> wrote:
Quote:


Engine gurus,
I have a problem with my engine that has me stumped. Maybe someone has seen
this situation before or has an idea for resolution.
I have a Barrett IO-390 (essentially same as IO-360) that began missing and
losing power in June. I tracked down several "problems" which the solution
to I thought would solve the power loss. I found one spark plug that seemed
to be a problem. Replaced all plugs and tested them before installation.
Problem still there. Checked resistance in harness. All good. Replaced
harness anyway. Problem still there. Sent P Mags back to factory for
overhaul. Essentially have new P Mags now. Problem still there. Cleaned
injectors and flow tested. Flows all equal. Cleaned fuel filter - nothing
there. There is no air filter when I run ram air, so nothing to inhibit air
flow. I checked the sniffle valve but no leak there.
On takeoff roll there seems to be slightly less power, but the power loss is
more noticeable (approx 20% loss) once airborne. At pattern altitude with
reduced power the engine runs ok. But as I add throttle (high RPM on prop)
the engine loses power as if it is loading up. The EGTs and CHTs are
normal. The RPM and MP are normal.
So, there you go. Any ideas?
Stan Sutterfield
RV-8A. Port Orange, FL



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PostPosted: Sat Aug 04, 2012 4:47 am    Post subject: Help me solve engine power loss Reply with quote

Have you checked the integrity of your engine electrical ground?
Steve Thomas
________________________________________________________________________


On Aug 3, 2012, at 6:55 PM, Speedy11(at)aol.com wrote:

Quote:


Engine gurus,
I have a problem with my engine that has me stumped. Maybe someone has seen this situation before or has an idea for resolution.
I have a Barrett IO-390 (essentially same as IO-360) that began missing and losing power in June. I tracked down several "problems" which the solution to I thought would solve the power loss. I found one spark plug that seemed to be a problem. Replaced all plugs and tested them before installation. Problem still there. Checked resistance in harness. All good. Replaced harness anyway. Problem still there. Sent P Mags back to factory for overhaul. Essentially have new P Mags now. Problem still there. Cleaned injectors and flow tested. Flows all equal. Cleaned fuel filter - nothing there. There is no air filter when I run ram air, so nothing to inhibit air flow. I checked the sniffle valve but no leak there.
On takeoff roll there seems to be slightly less power, but the power loss is more noticeable (approx 20% loss) once airborne. At pattern altitude with reduced power the engine runs ok. But as I add throttle (high RPM on prop) the engine loses power as if it is loading up. The EGTs and CHTs are normal. The RPM and MP are normal.
So, there you go. Any ideas?
Stan Sutterfield
RV-8A. Port Orange, FL









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BARRY CHECK 6



Joined: 15 Mar 2011
Posts: 738

PostPosted: Sat Aug 04, 2012 9:24 am    Post subject: Help me solve engine power loss Reply with quote

Stan:

Some ideas I had:
  • How did you clean the injectors?  A standard way is to soak them in Hoppies #9 Gun Solvent.  The flow could be all equal - But they could be all slightly restricted.
  • Does the fuel lines from the spider contact any part of the engine?  HEAT could be causing a vapor bubble.
  • Since you have a CS prop, do you think or feel the loading ONLY when increasing the RPM?  This could be a SLOW reacting Governor and that would cause loading.
  • Can you monitor your ALL your EGT 's at the same time and see if a cylinder drops in temperature at the same time loss of power occurs?  
  • The spark plug that was a problem:  Was it indicating Oil or Carbon?  Keep an eye on that plug and see if the problem begins again.  It could indicate a sticky Exhaust Valve.  So, replacing the plug will not fix the valve.
  • Have you done the Valve Wobble test (SB-388)?
  • OK, with this one I am reaching a bit: I have read about someone that "Improved" the intake air flow to the engine.  And in doing so, the forced air was so great that it disturbed the airflow through the Carb.  - I know you do not have a Carb, but how does it fly without the Ram Air?
  • Have you inspected the ducting - I'm guessing SCAT Tube.  Could that have an obstruction or could it be collapsing?
That's all for now...
Barry
=======================
On Fri, Aug 3, 2012 at 9:55 PM, <speedy11(at)aol.com (speedy11(at)aol.com)> wrote:
[quote] --> Engines-List message posted by: speedy11(at)aol.com (speedy11(at)aol.com)

Engine gurus,
I have a problem with my engine that has me stumped.  Maybe someone has seen this situation before or has an idea for resolution.
I have a Barrett IO-390 (essentially same as IO-360) that began missing and losing power in June.  I tracked down several "problems" which the solution to I thought would solve the power loss.  I found one spark plug that seemed to be a problem.   Replaced all plugs and tested them before installation.  Problem still there.  Checked resistance in harness.  All good. Replaced harness anyway.  Problem still there.  Sent P Mags back to factory for overhaul.  Essentially have new P Mags now.   Problem still there.   Cleaned injectors and flow tested. Flows all equal.  Cleaned fuel filter - nothing there.  There is no air filter when I run ram air, so nothing to inhibit air flow.  I checked the sniffle valve but no leak there.
On takeoff roll there seems to be slightly less power, but the power loss is more noticeable (approx 20% loss) once airborne.  At pattern altitude with reduced power the engine runs ok.  But as I add throttle (high RPM on prop) the engine loses power as if it is loading up.  The EGTs and CHTs are normal.  The RPM and MP are normal.
So, there you go.   Any ideas?
Stan Sutterfield
RV-8A. Port Orange, FL




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