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  #1  
Old 06-16-2021, 03:18 PM
Jesse's Avatar
Jesse Jesse is offline
 
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Location: X35 - Ocala, FL
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Default IO-540 at 2500rpm with EFII - drops cylinder

I am trying to work through a problem we are having with an RV-10 with an IO-540 and EFII. We have gotten to the point where we can get Cylinder 1 to drop (complete EGT drop and engine runs rough) by running the engine at 2500 rpm. The manifold pressure doesn't matter. We have replaced the injector. We have swapped the injector power wire with cylinder 3 (to verify it isn't a bad crimp). We have changed ECU's vie the ECU 1/2 switch. We have run on both and either mag individually. Nothing gets rid of this problem. At 2530 rpm there is no problem. At 2450 rpm there is no problem. At 2500 on the money, it drops cylinder 1. No other cylinder, and no exception. Every time, cold engine or hot engine, lean or rich, in flight or on the ground.

My main questions is, what could possibly be magic about 2500 rpm that could make this happen.

We though about a stuck valve at some point, but that would not just be at one specific rpm, at least not that I could imagine.

Thoughts?
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  #2  
Old 06-16-2021, 03:38 PM
BillL BillL is offline
 
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Location: Central IL
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Quote:
Originally Posted by Jesse View Post
I am trying to work through a problem we are having with an RV-10 with an IO-540 and EFII. We have gotten to the point where we can get Cylinder 1 to drop (complete EGT drop and engine runs rough) by running the engine at 2500 rpm. The manifold pressure doesn't matter. We have replaced the injector. We have swapped the injector power wire with cylinder 3 (to verify it isn't a bad crimp). We have changed ECU's vie the ECU 1/2 switch. We have run on both and either mag individually. Nothing gets rid of this problem. At 2530 rpm there is no problem. At 2450 rpm there is no problem. At 2500 on the money, it drops cylinder 1. No other cylinder, and no exception. Every time, cold engine or hot engine, lean or rich, in flight or on the ground.

My main questions is, what could possibly be magic about 2500 rpm that could make this happen.

We though about a stuck valve at some point, but that would not just be at one specific rpm, at least not that I could imagine.

Thoughts?
I would blame it on software and a bad map, or a weird injector.
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Last edited by BillL : 06-16-2021 at 03:41 PM.
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  #3  
Old 06-16-2021, 03:42 PM
FlyingDiver FlyingDiver is online now
 
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Quote:
Originally Posted by BillL View Post
I would blame it on software and a bad map.
Which could actually be a hardware problem in the EFII unit - bad memory corrupting the map.
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  #4  
Old 06-16-2021, 04:04 PM
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koupster koupster is offline
 
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Jesse,

Since you've done the fuel injector trouble-shooting, I'd suspect that you're losing spark on #1. If you have a timing light or engine analyser with an inductive pickup, you can clip it on a #1 spark plug lead to check.
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  #5  
Old 06-16-2021, 06:46 PM
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Originally Posted by koupster View Post
Jesse,

Since you've done the fuel injector trouble-shooting, I'd suspect that you're losing spark on #1. If you have a timing light or engine analyser with an inductive pickup, you can clip it on a #1 spark plug lead to check.
The problem with that is that it only fails at 2500 rpm.
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  #6  
Old 06-16-2021, 07:07 PM
TS Flightlines TS Flightlines is offline
 
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Whats Robert say> maybe the computer doesnt know the engine is suppose to run at 2500. Over rev protection like an MSD Chip?

Tom
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  #7  
Old 06-16-2021, 07:12 PM
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Quote:
Originally Posted by Jesse View Post
The problem with that is that it only fails at 2500 rpm.
Exactly. If the timing light or engine analyser with an inductive pickup on the #1 ignition lead, shows spark at 2400 RPM and no spark at 2500 RPM, you've probably isolated the problem to the EFII unit.
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Last edited by koupster : 06-16-2021 at 09:02 PM. Reason: add comma
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  #8  
Old 06-16-2021, 07:13 PM
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Quote:
Originally Posted by koupster View Post
Exactly. If the timing light or engine analyser with an inductive pickup on the #1 ignition lead, shows spark at 2400 RPM and no spark at 2500 RPM you've isolated the problem to the EFII unit.
It runs great at 2700 rpm. I donít think itís a over-rev issue.
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  #9  
Old 06-16-2021, 07:14 PM
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Mike S Mike S is offline
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Is this EFII brand, or the EFII that SDS sells??
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  #10  
Old 06-16-2021, 07:15 PM
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Is this EFII brand, or the EFII that SDS sells??
EFII brand.
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