Can someone please help me understand the EGT changes one would see with a poor spark or cylinder?
I am trying to find the bad spark plug or wire set or possible even the cylinder itself by watching the EGT changes when one ignition system is turned off.
The engine is a IO-540 with dual Lightspeed III ignition systems.
I assume that when one of the two ignition systems is turned off then the mixture is not burning as quickly and cleanly so I would suspect that the EGT in the cylinders will all rise because the mixture is still burning as the exhaust valve is opening so then since my EGT sensors are exactly 2 inches from the exhaust flange then the EGT indications would be hotter. Is that accurate.
If the spark plug in a certain cylinder is not sparking at all then naturally that cylinder will show as a cold EGT indication.
But what is the spark is intermittent?
At a 1000 RPM idle with both ignition systems on I see 11.7 MAP and the following EGTs:
1026
980
1026
1019
1095
1060
I turn off the A ignition system and when operating only on the B ignition system the engine is smooth and I see 12.1 MAP and all of the EGTs rise by this amount F:
33
21
40
13
8
73 (so #6 showed a much higher EGT rise than the others.
I then run both ignition systems to let everything stabilize and then turn off the B ignition system and the engine has a slight popping sound and I see a MAP of 12.5 with all of the cylinders getting an EGT rise except #6 and it runs cooler that before:
15
12
9
23
10
MINUS 9
So cylinder #6 has the highest EGT rise when the A system is turned off and then it is also the only cylinder to get cooler when the B system is turned off.
So does the cyber collective agree that perhaps the B system spark plug of the wires to that one cylinder are lazy?
I want to go up and do the complete SAVVY engine LOP test and the ignition stress test plus the intake manifold test the next flight but I want to see if I can fix it first.
THANKS for your help!!!
I am trying to find the bad spark plug or wire set or possible even the cylinder itself by watching the EGT changes when one ignition system is turned off.
The engine is a IO-540 with dual Lightspeed III ignition systems.
I assume that when one of the two ignition systems is turned off then the mixture is not burning as quickly and cleanly so I would suspect that the EGT in the cylinders will all rise because the mixture is still burning as the exhaust valve is opening so then since my EGT sensors are exactly 2 inches from the exhaust flange then the EGT indications would be hotter. Is that accurate.
If the spark plug in a certain cylinder is not sparking at all then naturally that cylinder will show as a cold EGT indication.
But what is the spark is intermittent?
At a 1000 RPM idle with both ignition systems on I see 11.7 MAP and the following EGTs:
1026
980
1026
1019
1095
1060
I turn off the A ignition system and when operating only on the B ignition system the engine is smooth and I see 12.1 MAP and all of the EGTs rise by this amount F:
33
21
40
13
8
73 (so #6 showed a much higher EGT rise than the others.
I then run both ignition systems to let everything stabilize and then turn off the B ignition system and the engine has a slight popping sound and I see a MAP of 12.5 with all of the cylinders getting an EGT rise except #6 and it runs cooler that before:
15
12
9
23
10
MINUS 9
So cylinder #6 has the highest EGT rise when the A system is turned off and then it is also the only cylinder to get cooler when the B system is turned off.
So does the cyber collective agree that perhaps the B system spark plug of the wires to that one cylinder are lazy?
I want to go up and do the complete SAVVY engine LOP test and the ignition stress test plus the intake manifold test the next flight but I want to see if I can fix it first.
THANKS for your help!!!