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  #1  
Old 05-16-2021, 03:57 PM
Flyyak Flyyak is offline
 
Join Date: Jan 2012
Location: Birmingham alabama
Posts: 123
Default #1 cylinder EGT high on takeoff

I have an I0360 with Airflow Performance fuel injectors that have been calibrated. Now have 300 hours and all has run perfectly up until a few hours ago I started to notice in the yellow on #1 on takeoff. I have since inspected and cleaned all injectors. There was no obstruction or debris. After test flight, #1 in the red but would come back in yellow and green when I reduced throttle. I then disconnected all injection line, used 4 baby food jars, initiated boost pump and all fuel collections were identical. Next swapped Alcor 86255 EGT probes between #1 & 3 and test flew again. #3 registered high and I then installed a new probe in #1 and reinstalled #3 back in #3. Test flew and #1 registered in the red on takeoff, would come down to yellow and green on throttle reduction.

Please let me know other suggestions to check. I generally run LOP and the EGTs are within 10* between high and low and CHTs are very close also (#4 highest where oil cooler is located). I have two PMags and they have been flawless to date. Engine has really run very smooth, starts easy cold or hot. Thanks.
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  #2  
Old 05-16-2021, 04:07 PM
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Check for induction leaks? Perhaps even replace the intake gasket and pipe clamp if your engine is so equipped.
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  #3  
Old 05-16-2021, 04:16 PM
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Out of curiosity, how close to the exhaust valve are the probes installed? Are they all the same distance?
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  #4  
Old 05-16-2021, 05:55 PM
Flyyak Flyyak is offline
 
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EGT probes are all the same distance and have worked great for 300 hrs. Thought it was the probe when I changed 1 to 3; photo attached. I will check gaskets. It is odd that when I changed the probes, the #3 probe placed in #1 exhaust seemed to show normal temps. Thanks
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  #5  
Old 05-16-2021, 07:27 PM
BillL BillL is offline
 
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If the lean limit spread is good, the EGT is likely a probe issue. EGT's are not really comparable. CHT is a better indication of balance.

Have you checked the thermocouple wires and connections?
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Last edited by BillL : 05-16-2021 at 07:47 PM.
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Old 05-17-2021, 07:35 AM
lr172 lr172 is offline
 
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Thermocouples are sensitive to poor wiring connections, so maybe start there. If problems move with a probe swap, seems logical that the probe or wiring is to blame.
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  #7  
Old 05-17-2021, 06:00 PM
BoydBirchler BoydBirchler is offline
 
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Location: Indianapolis
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Induction leak is not likely. An induction leak would leak the most at partial throttle (like while at idle, because that is when the differential between manifold pressure and ambient pressure is greatest) and least at full throttle (when the differential is almost nil).

So reducing power, as was indicated, would increase an induction leak (making the mixture worse not better). Things got better with the reduction, so an induction leak is ruled out!

Last edited by BoydBirchler : 05-17-2021 at 06:15 PM.
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Old 05-17-2021, 07:35 PM
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vlittle vlittle is offline
 
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Characteristic of only one plug firing on that cylinder. Easy to check.
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Old 05-17-2021, 08:26 PM
Captain Avgas Captain Avgas is offline
 
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Quote:
Originally Posted by lr172 View Post
Thermocouples are sensitive to poor wiring connections, so maybe start there. If problems move with a probe swap, seems logical that the probe or wiring is to blame.
The OP said in his first post that he had already performed a probe swap and the high EGT stayed with the offending cylinder #1 (didn't move with the probe). So obviously not a probe. But he then replaced the #1 probe anyway...no difference.

I'm with Vern on this one....one plug not firing properly on Cylinder #1. Could be the plug itself, or it could be the Pmag driving it. As Vern said, easy to check the plug.
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Last edited by Captain Avgas : 05-17-2021 at 08:33 PM.
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  #10  
Old 05-18-2021, 01:05 AM
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rv8ch rv8ch is offline
 
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Quote:
Originally Posted by Captain Avgas View Post
...
I'm with Vern on this one....one plug not firing properly on Cylinder #1. Could be the plug itself, or it could be the Pmag driving it. As Vern said, easy to check the plug.
And check the plug wires. Any crackling or popping in the radio? That could indicate an intermittent connection. You might need to move the plug wire around when checking resistance to get it to short. I had this problem with one plug wire.
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