Jim P
Well Known Member
Need some hive-mind input on a #4 EGT problem.
Just completed condition inspection and was doing leak check/mag check. During annual, mags timed out right on the money, no need to adjust. Prior to CI, everything appeared normal. Plugs and injectors cleaned.
1) #4 compression 77-78/80
2) Running Tempest fine-wire plugs/ Slick mags (both overhauled at 500 hrs).
3) Idle run, all EGTs are about even, as are CHTs.
4) Doing run up, #4 EGT rises fast, ends up a good 200 degs above the other three which are about even. I can tell there's some roughness as throttle advances.
5) On mag check, seeing normal rise in EGT for both mags across all cylinders.
6) #4 lower fouls easily, and is rougher on mag check, but EGT does not fall off (at least getting partial firing) during mag check. CHT not falling off either.
7) Checked fuel flow with boost pump - #4 seems to align with others in fuel volume for given time.
8) Swapped both top and bottom plugs with #2 cylinder, one at a time, no change, so I rule out a bad plug.
9) All EGTs seem normal at idle, doesn't appear to be induction leak.
With #4 lower plug fouling somewhat, I suspect a possible issue with harness wire. What else am I missing?
Jim
Just completed condition inspection and was doing leak check/mag check. During annual, mags timed out right on the money, no need to adjust. Prior to CI, everything appeared normal. Plugs and injectors cleaned.
1) #4 compression 77-78/80
2) Running Tempest fine-wire plugs/ Slick mags (both overhauled at 500 hrs).
3) Idle run, all EGTs are about even, as are CHTs.
4) Doing run up, #4 EGT rises fast, ends up a good 200 degs above the other three which are about even. I can tell there's some roughness as throttle advances.
5) On mag check, seeing normal rise in EGT for both mags across all cylinders.
6) #4 lower fouls easily, and is rougher on mag check, but EGT does not fall off (at least getting partial firing) during mag check. CHT not falling off either.
7) Checked fuel flow with boost pump - #4 seems to align with others in fuel volume for given time.
8) Swapped both top and bottom plugs with #2 cylinder, one at a time, no change, so I rule out a bad plug.
9) All EGTs seem normal at idle, doesn't appear to be induction leak.
With #4 lower plug fouling somewhat, I suspect a possible issue with harness wire. What else am I missing?
Jim