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12-11-2019, 03:59 PM
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Join Date: Dec 2008
Location: Northern Ireland
Posts: 16
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fluctuating rpm / map
Hi.I have a new titan io370 with dual pmags, c/s prop and afp150 vertical induction fuel injection system. It runs fine apart from at 1150rpm when the rpm fluctuates between 1100-1200. Also when running at 2300rpm the map fluctuates by about 1". All other rpm settings seem stable in rpm and map. I'm guessing that at 2300 the governor is maintaining the rpm. Not sure if its a weird resonance or something else is going on. The engine is brand new and has around 4 hours flight time on the aircraft. Has anyone else experienced this issue and how did you solve it?
Thanks
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12-12-2019, 06:05 AM
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Join Date: Jan 2005
Posts: 1,024
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The governor will not maintain 2300 rpm un less you set it to 2300rpm. If it is set for take off RPM then it will not kick in until you reach that RPM. So it is unlikely that the rpm is being maintained by the governor at 2300rpm.
What type of indications are u seeing? Electronically generated or steam gauges generated? can you hear the rpm change at 1150 or do you just see it on the tach?
Merry Christmas,
Mahlon
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"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
Last edited by mahlon_r : 12-12-2019 at 06:07 AM.
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12-12-2019, 06:21 AM
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Join Date: Apr 2010
Location: Covid Country-SoCal
Posts: 1,081
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Does the EGT rise when the MP wanders at idle? According to Vic, (great webinar Vic!) you may have an intake leak. Just a thought.
-Marc
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RV-10
N814RV
2020 Donation Made
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12-12-2019, 06:43 AM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Do you have restrictors in your manifold pressure lines?
If not, the P-mag timing could be bouncing around, causing the fluctuations.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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12-12-2019, 08:33 AM
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Join Date: Dec 2008
Location: Northern Ireland
Posts: 16
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There is a restrictor in the manifold pressure line, I believe as supplied by Vans so i dont know if its small enough. It only fluctuates at 11-1200rpm and you can hear it change. From the garmin pilot app I can see that as the rpm decreases the map increases.
During flight when we set the rpm to 2300 its stable but the map fluctuates.
I haven't noticed the egt following any pattern.
The instrumentation is all garmin g3x.
Is it possible that there is something resonating at those frequencies?
Miller
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12-12-2019, 08:56 AM
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Join Date: Nov 2014
Location: Richmond Hill, GA (KLHW)
Posts: 2,183
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Miller,
Download the engine data and upload it to Savvy Analysis for review. Allow the data to be shared and post a link here.
__________________
Ray
RV-7A - Slider - N495KL - First flt 27 Jan 17
O-360-A4M w/ AFP FM-150 FI, Dual PMags, Vetterman Trombone Exh, SkyTech starter, BandC Alt (PP failed after 226 hrs)
Catto 3 blade NLE, FlightLines Interior, James cowl, plenum & intake, Anti-Splat -14 seat mod and nose gear support
All lines by TSFlightLines (aka Hoser)
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12-12-2019, 09:03 AM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,642
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You have 4 hours on this engine and you are already flying at 2300 RPM? Was it broken in on a test stand?
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.
Michael Robinson
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Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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12-12-2019, 09:55 AM
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Join Date: Dec 2008
Location: Northern Ireland
Posts: 16
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Yes, the break-in was done by titan.
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12-13-2019, 07:58 AM
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Join Date: Jan 2005
Posts: 1,024
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have you tried adjusting the mixture leaner, when it is doing it, to see if that will change anything?
Good Luck,
Mahlon
__________________
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
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12-13-2019, 08:41 AM
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Join Date: Jun 2005
Location: Georgetown, TX
Posts: 326
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Hmmm...
On MAP irregularities: I know Van's provides "restricted" AN fittings for the Oil Pressure and Fuel Pressure -- didn't know about the MAP.
If you are using the parts that came in the IE VMP install kit, those are not sufficient to damp out the pulses seen in the MAP when connected to the #3 intake port.
You will need OMEGA Engineering Snubber or similar damping between the #3 intake port and the MAP sender ( https://www.omega.com/en-us/sensors-.../p/PS-SNUBBERS). Or, drill/tap another hole in the intake manifold and use that for the MAP source.
On RPM: How is the RPM being sensed? Mechanical tach/sensor to EFIS, or Ignition Box output to EFIS? I would obtain an optical tachometer (see omega engineering or sporty's or AC Spruce) and verify the numbers before doing anything else.
Good luck!
B
__________________
Brian Decker
Retired Firmware Guy and Airplane Builder
2020 RV-14 QB -- Under construction - Tailcone & Empennage Complete.
2018 RV-7 QB -- Built, Flying
2007 RV-7 QB -- Built, Drowned, Resurrected and flying
1998 RV-8 QB -- Started, Sold
1986 Mooney 205SE
1980 Mooney 231
Aided and abetted building a number of other RV's.
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