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Help me solve engine power loss

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speedy11(at)aol.com
Guest

Posted: Fri Aug 03, 2012 5:58 pm Post subject: Help me solve engine power loss

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
Guest

Posted: Fri Aug 03, 2012 6:22 pm Post subject: Help me solve engine power loss

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

- The Matronics Engines-List Email Forum -

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Kelly McMullen

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

Posted: Fri Aug 03, 2012 9:29 pm Post subject: Help me solve engine power loss

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

- The Matronics Engines-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?Engines-List

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD

lists(at)stevet.net
Guest

Posted: Sat Aug 04, 2012 4:47 am Post subject: Help me solve engine power loss

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

- The Matronics Engines-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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BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Sat Aug 04, 2012 9:24 am Post subject: Help me solve engine power loss

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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