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  #11  
Old 01-26-2020, 01:21 PM
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RV7A Flyer RV7A Flyer is offline
 
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Location: US
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Quote:
Originally Posted by lr172 View Post
And what do you say to all the EFII users that need to stand at a running engine to time it? Rip it all out?

Larry
I would say that might be necessary risk, whereas idle mixture adjustment on an injection throttle body with the engine running is an UNnecessary risk, since it can be easily done another way with considerably less risk.

Given the option to accomplish a task and reduce or eliminate a risk, I'd choose that option. But that's just me...I'd rather reduce or eliminate risks than tempt fate unnecessarily.
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  #12  
Old 01-26-2020, 01:31 PM
ChrisMcC ChrisMcC is offline
 
Join Date: Mar 2014
Location: Colorado Springs
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Thank you all for your replies. Maybe I wasn't terribly clear:

(1) the 100 RPM rise would indicate an overly rich idle mixture. Yes, ~50 is normal.

(2) the after fires at idle would indicate an overly lean idle mixture.

So, it's hard to know what directly to go. I will try to MAP technique. Great suggestion. I will also return the idle mixture closer to where it was, and investigate the sniffle valve issue.
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  #13  
Old 01-26-2020, 03:33 PM
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snopercod snopercod is offline
 
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To elaborate on my previous statement that too rich can cause backfiring, I have evidence. This video was taken at an airport with a 8,000' density altitude, after leaning for max RPM during the runup. It wasn't lean enough and the engine backfired and died right there on the runway. The black smoke is evidence of too rich a mixture. I leaned aggressively and got her running again, then took off.

https://www.dropbox.com/s/ay7prqm4i6...nnial.mp4?dl=0
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  #14  
Old 01-27-2020, 10:50 AM
danny danny is offline
 
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Location: puyallup, wa
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Default backfire/afterfire?

In my own humble opinion an easy thing to check (just to cover your bases) is looking at your exhaust for leakage at the gasket flanges. Do a quick look with a mirror and a flashlight just to be able to cross that off your list of possible causes.
I live under the downwind leg for 35 at KPLU and hear a lot of snap, crackle and pop noises.....usually from gaskets leaking.
Later today I'll be adjusting idle on my own plane.
good luck
danny
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  #15  
Old 01-27-2020, 05:05 PM
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RV8JD RV8JD is offline
 
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Default Off Topic Warning!

Quote:
Originally Posted by danny View Post
I live under the downwind leg for 35 at KPLU and hear a lot of snap, crackle and pop noises.....usually from gaskets leaking.
danny
Hopefully the noises aren't from people shooting at airplanes near KPLU, including at "the red single engine plane"! (Just kidding, just kidding!)

But this is disconcerting:

https://www.faasafety.gov/SPANS/noti....aspx?nid=9832

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Last edited by RV8JD : 01-27-2020 at 05:08 PM.
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  #16  
Old 01-31-2020, 10:31 AM
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bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
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Default On leaks...

Unfortunately, the Southwest Airlines Flu Virus, Variant 1 (SWAFV1) knocked me out for a few days, but during my convalescence I did a virtual walk around of my engine (IO-360-A1B6) looking for possible manifold leaks -- I think I've identified a few that I should share:

1. Bad sniffle valve -- check ball gets stuck, and the "suck" doesn't close it cleanly and lets air in.
2. Manifold pressure tap -- 45? AN fitting on #3 Jug (YMMV), to a hose, to another AN fitting on to the transducer manifold, to another hose to EI system. If anything along this path leaks it's going to let air in. Use Loctite 565 on those NPT fittings.
3. Gaskets around the intake runners -- top and bottom.
4. Gasket between FI Servo and Intake plenum.
5. Then the more gross errors - cracked intakes, cracked intake plenum, etc.

Personally, I'm going to revisit #2 on my setup as I had discovered that one of the tygon hoses had popped off the Plasma III.

Cheers!
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2020 RV-14 QB -- Under construction - Tailcone & Empennage Complete.
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1998 RV-8 QB -- Started, Sold
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