---------------------------------------------------------- Engines-List Digest Archive --- Total Messages Posted Fri 08/03/12: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:58 PM - Help me solve engine power loss (speedy11@aol.com) 2. 07:22 PM - Re: Help me solve engine power loss (Tim Andres) 3. 08:30 PM - Re: Help me solve engine power loss (Robert Buckthal) 4. 10:29 PM - Re: Help me solve engine power loss (Kelly McMullen) ________________________________ Message 1 _____________________________________ Time: 06:58:31 PM PST US Subject: Engines-List: Help me solve engine power loss From: speedy11@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 ________________________________ Message 2 _____________________________________ Time: 07:22:06 PM PST US Subject: Re: Engines-List: Help me solve engine power loss From: Tim Andres 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@aol.com wrote: > > 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 > > > > > > > ________________________________ Message 3 _____________________________________ Time: 08:30:30 PM PST US Subject: Re: Engines-List: Help me solve engine power loss From: Robert Buckthal An engine missfire on a 4 cyl is usually a pretty violent event. It's not the same as losing power. From your post it sounds like the problem is not a missfire, rather you're just not getting the same old get-up-n-go. Have you tried looking at fuel pressure. When it loses power in flight turn on the boost pump. You might also rig-up a mechanical gauge in the cockpit to confirm that your electronic gauge is accurate. Do it in flight. Fuel pressure on the ground is not the same as fuel pressure in flight. I like Tims response. If the engine is mechanically sound then the most likely cause of power loss is not enough fuel. Bob On Fri, Aug 3, 2012 at 7:18 PM, Tim Andres wrote: > > 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@aol.com wrote: > > > > > 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 > > > > > > > > > > > > > > > > ________________________________ Message 4 _____________________________________ Time: 10:29:14 PM PST US Subject: Re: Engines-List: Help me solve engine power loss From: Kelly McMullen 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, wrote: > > 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. 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