Cylinder 5 Tuning Issue

[lpaaruule]

Hello,

I've been doing some full throttle ground run-up during the tuning process, and trying to get the 100F change from full rich to peak lean.

When I lean at full throttle the EGTs rise as expected except for cylinder 5, which drops from 1417F to 1265F. The other cylinders EGTs range form 1200F to 1300F. Cylinder 5 CHT steadily rises with the rest, so I believe that it's still firing correctly.

My thought is that cylinder 5 might be extremely rich and burning fuel in the exhaust, but I'm not sure. Anyone else experienced this?

Also, I don't quite have 100F change form full rich to peak lean on some of the cylinders, so I'm tempted to richen a little more, but with cylinder 5 acting up, I'm not sure what to do. My fuel flow is 9.5GPH at ~3000RPM Static

[vwglenn]

I'd start by swapping the EGT probes on 3 and 5 and see if the problem stays on that cylinder or moves with the probe.

As far as the 100 degree EGT thing goes, I'd pick one (my most consistent) cylinder to read that from. Trying to get them all to gel seems like a long tail chase that would yield little in the way of results. Personally I'd rather have it running a little rich than too lean.