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  #1  
Old 02-22-2021, 04:52 PM
Kupde Kupde is offline
 
Join Date: May 2016
Location: Tampa,Fl
Posts: 44
Default EGT Fluctuation

Just changed out the fuel restrictions on cyl#3 and #4 on my RV-10 from an 0.028 to a 0.027. Test flight shows a very brief EGT drop(3 to 5 seconds) while going through the leaning operation on cylinder #3 only. Cylinder #3 drops about 200 degrees below the others(1200F vs 1400F) for the 3 to 5 seconds and then recovers with no further fluctuations. This repeats anytime going back through a leaning operation at different altitudes and engine settings. Never seen this before- anyone have any thoughts?

Kevin
RV-10
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  #2  
Old 02-22-2021, 05:25 PM
Bill Boyd's Avatar
Bill Boyd Bill Boyd is offline
 
Join Date: Sep 2006
Location: Landing field "12VA"
Posts: 1,637
Default

Very interested in the replies you get on this. I'll be balancing my injectors soon as I progress through phase 1.

My EGT on one cyl scrolled quickly downward and back up again shortly before the Dynon-supplied probe in question went T.U. for good, and had to be replaced at about 5 hours TT.
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Bill Boyd

Hop-Along Aerodrome (12VA)
RV-6A - N30YD - Built '98 / sold '20
RV-10 - N130YD - Phase 1 flying

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  #3  
Old 02-22-2021, 10:11 PM
Lt Dan Lt Dan is offline
 
Join Date: Dec 2014
Location: Utah
Posts: 96
Default

What did the CHT do?
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09 RV-8
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  #4  
Old 02-23-2021, 05:34 AM
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Raymo Raymo is offline
 
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Location: Richmond Hill, GA (KLHW)
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Sounds like #3 is running too lean. Can you upload the data to Savvy and share a link?
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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
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  #5  
Old 02-23-2021, 07:16 AM
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bjdecker bjdecker is online now
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 646
Default

Quote:
Originally Posted by Kupde View Post
Just changed out the fuel restrictions on cyl#3 and #4 on my RV-10 from an 0.028 to a 0.027. Test flight shows a very brief EGT drop(3 to 5 seconds) while going through the leaning operation on cylinder #3 only. Cylinder #3 drops about 200 degrees below the others(1200F vs 1400F) for the 3 to 5 seconds and then recovers with no further fluctuations. This repeats anytime going back through a leaning operation at different altitudes and engine settings. Never seen this before- anyone have any thoughts?

Kevin
RV-10
I would be very suspicious of that EGT probe/wiring. I had a similar pre-failure signature on one of my ALCOR EGT probes very early on (~50 hours).

Swap the probe, see if the signature follows the probe -- if so, replace the probe.

Usually, issues with fuel injectors resolve themselves VERY quickly -- like a stumble that the EIS doesn't even see, or they don't resolve at all -- total blockage.
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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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  #6  
Old 02-23-2021, 07:37 AM
lr172 lr172 is offline
 
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Location: Schaumburg, IL
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Quote:
Originally Posted by bjdecker View Post
I would be very suspicious of that EGT probe/wiring. I had a similar pre-failure signature on one of my ALCOR EGT probes very early on (~50 hours).

Swap the probe, see if the signature follows the probe -- if so, replace the probe.

Usually, issues with fuel injectors resolve themselves VERY quickly -- like a stumble that the EIS doesn't even see, or they don't resolve at all -- total blockage.
+1

Sounds more like an indication problem than a fuel delivery problem. Pretty hard to have a fuel issue that can cause an EGT to drop then regain 200* in 3 seconds.

Larry
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  #7  
Old 02-23-2021, 07:37 AM
Kupde Kupde is offline
 
Join Date: May 2016
Location: Tampa,Fl
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https://apps.savvyaviation.com/fligh...3-b3c28bb00ca0

Not sure if you can get to the data with the link above? Also, no change in CHT and I'll do as suggested with the EGT probe.

Thanks

Kevin
RV-10
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  #8  
Old 02-23-2021, 08:04 AM
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Raymo Raymo is offline
 
Join Date: Nov 2014
Location: Richmond Hill, GA (KLHW)
Posts: 2,324
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Quote:
Originally Posted by Kupde View Post
https://apps.savvyaviation.com/fligh...3-b3c28bb00ca0

Not sure if you can get to the data with the link above? Also, no change in CHT and I'll do as suggested with the EGT probe.

Thanks

Kevin
RV-10
Thanks for the link. Definitely a probe connection issue, as mentioned above. GAMI spread is pretty good with #2 trending leaner.

Time: 00:14:28-00:14:54
EGT2 peaked at 12.2
EGT3 peaked at 12
EGT1 peaked at 11.8
EGT4 peaked at 11.8
EGT5 peaked at 11.8
EGT6 peaked at 11.8
GAMI spread is 0.4
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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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  #9  
Old 02-23-2021, 08:56 AM
bjdecker's Avatar
bjdecker bjdecker is online now
 
Join Date: Jun 2005
Location: Georgetown, TX
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Default I love data...

You can definitely see something going on there --

EGT on #3 drops out frequently, 9:08, 16:20, 19:29, and so on, regardless of fuel flow settings.
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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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  #10  
Old 02-23-2021, 02:51 PM
bjdecker's Avatar
bjdecker bjdecker is online now
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 646
Default Another oddity...

Keep an eye on the #2 CHT.

Note 11:41 to 14:32 and 21:08 to 26:41 -- #2 CHT is NOT following the normal distribution or rate of change.

This tells me the #2 Cylinder is burning too hot / too fast as the fuel flow increases (richer:faster, leaner:slower), change to a smaller orifice (e.g. .027" from .028") and see if that curve flattens out.
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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.

Last edited by bjdecker : 02-23-2021 at 02:57 PM. Reason: updated recommendations.
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