Lower than normal EGT on 1 cylinder

alcladrv · #1 02-12-2008, 02:45 PM

In my -7A, I use an O-360 with a fixed pitch Sensenich prop. My left ignition is a Slick mag to the bottom plugs. My right ignition is a Lightspeed Plasma II to the top plugs. The runup was normal after a longer than normal warmup because of a 25F outside temp. In the past during cruise my EGTs have run within 100 degrees F. With a little Carb Heat, I can get them within 50 degrees F.

Yesterday, my #1 cylinder EGT was about 150 degrees F low in cruise. I had leaned to peak and was running about 70% power with carb heat about 1/3 on. The OAT was -25F. After about an hour, I noticed that all 4 four cylinders were again within 50 degrees F.

Any ideas on the cause? Was the plug possibly fouled and then the lead was burned off?

Thanks,

Mike

Rivethead · #2 02-12-2008, 05:47 PM

I'm thinking you had a fould plug. That would make sense since you wouldn't be getting a complete burn you would be throwing a little raw gas out the pipe thus cooling your EGT.

allbee · #3 02-12-2008, 07:47 PM

I would be wanting to know if a sensor is acting up, switch with one of the other if possible and see if it goes to another cylinder. If it stays with no.1 than replace the spark plugs on no.1. Or start with new plugs in no.1 and then switch the sensor with another after that. Might be able to tell if you just remove the plugs, should be wet compared to the other cylinders if that's the problem.