mchargmg
Well Known Member
Hi all,
I fly an RV-6A with an IO-360 (180 HP) and CS prop out of KLFY Colorado. I routinely run Lean of Peak (LOP) when just cruising around. Typical cruise numbers up at our altitude are:
WOT
MAP: 21"
RPM: 2350
Fuel flow ROP: 9.5 gal/hr
Fuel flow LOP: ~7 gal/hr
Cylinder head temps:
ROP: 370
LOP: 330
Exhaust Gas Temps:
Peak: 1420-1450
LOP: Peak -30
The engine has about 580 hours on it, all compressions in mid-high 70s.
So my issue is this. Over the last couple of flights, I have noticed that when I lean back for LOP operations, my EGT will come down as normal, and then suddenly number 2 cylinder EGT will start fluctuating and then wind up higher than normal by 50 degrees or so. The cylinder head temps are all normal, and the engine "sounds fine." No noticeable decrease in performance or roughness.
I would chalk this up to a flakey sensor, but it only happens when LOP. When I am ROP all the EGTs are close to each other (typically within maybe 20 degrees or so). This is very repeatable. Last flight I think I went from ROP to LOP 3 times, with the same result each time.
So my question is: what is my engine telling me? The only thing I can think of that we have changed were the spark plugs during the last conditional. When I think of a higher EGT I think of running lean. Could this be a sign that that the injector on that cylinder is either partially blocked, or somehow otherwise compromised? Any suggestions are appreciated.
Blue skies
Geoff
I fly an RV-6A with an IO-360 (180 HP) and CS prop out of KLFY Colorado. I routinely run Lean of Peak (LOP) when just cruising around. Typical cruise numbers up at our altitude are:
WOT
MAP: 21"
RPM: 2350
Fuel flow ROP: 9.5 gal/hr
Fuel flow LOP: ~7 gal/hr
Cylinder head temps:
ROP: 370
LOP: 330
Exhaust Gas Temps:
Peak: 1420-1450
LOP: Peak -30
The engine has about 580 hours on it, all compressions in mid-high 70s.
So my issue is this. Over the last couple of flights, I have noticed that when I lean back for LOP operations, my EGT will come down as normal, and then suddenly number 2 cylinder EGT will start fluctuating and then wind up higher than normal by 50 degrees or so. The cylinder head temps are all normal, and the engine "sounds fine." No noticeable decrease in performance or roughness.
I would chalk this up to a flakey sensor, but it only happens when LOP. When I am ROP all the EGTs are close to each other (typically within maybe 20 degrees or so). This is very repeatable. Last flight I think I went from ROP to LOP 3 times, with the same result each time.
So my question is: what is my engine telling me? The only thing I can think of that we have changed were the spark plugs during the last conditional. When I think of a higher EGT I think of running lean. Could this be a sign that that the injector on that cylinder is either partially blocked, or somehow otherwise compromised? Any suggestions are appreciated.
Blue skies
Geoff