Last week I was flying to SBA in my Lance (TIO540), and about an hour into the flight my engine started running very rough. I had not changed anything for several minutes beforehand. Attached is the EDM700 graph of the event, EGTs on top, CHTs below. I was at ~65% power at 9500', 19 gph (I have FF, but not MP/RPM). When it happened (at ~17:43), I immediately pushed the mixture to ~24 gph, with no change in roughness. After a bit of checking mags, throttle, prop, fuel pump with no change, I told center I was diverting to PRB (1200' overcast, and was just behind me) due to a rough engine and started decending. After several minutes and at reduced power, it smoothed out somewhat and I was able to shoot the RNAV approach.
The graph shows the #1 EGT jumped 180 F, and was eratic after for 10+ minutes. #1 CHT followed the higher #1 EGT. The #3 and #5 EGTs dropped 400 - 600 F for about 4 minutes (with CHT's tracking) then mostly came back to normal in the following minutes.
I called my mechanic after landing, and he thought maybe a fouled/bad plug. I did a few runups/mag checks, and there was no problems, so flew home. The next day, I did more runups including full power, etc. The first few showed #1 EGT high (+200) but only #5 going somewhat lower, then the issue "slowly went away" again. LOP mag checks at 75% power showed no problems.
I've talked with my mechanic, and I'm now on his schedule for about a week out. I'm not a mechanic, but here's my thoughts.
1. Not a probe related issue since #1, #3, #5 all showed related but different issues. Also CHT's tracked EGT's.
2. Not an induction leak, since they don't typically "fix" themselves?
3. Not a spark related issue, since there was no change on L or R mag. Also a later LOP mag check showed no problems.
4. A restricted flow in injector #1 that mostly cleared itself. Would that cause #3 and #5 to be affected? (Note that 1, 3, & 5 are all on the right side, if that is any clue.)
5. A restricted flow in #1, and [mostly] blocked in #3 and #5, until they became unblocked.
So, the above is my "non-Savvy Puzzler" for this month! Happy Thanksgiving to all. I'd appreciate any education and comments you might have.
The graph shows the #1 EGT jumped 180 F, and was eratic after for 10+ minutes. #1 CHT followed the higher #1 EGT. The #3 and #5 EGTs dropped 400 - 600 F for about 4 minutes (with CHT's tracking) then mostly came back to normal in the following minutes.
I called my mechanic after landing, and he thought maybe a fouled/bad plug. I did a few runups/mag checks, and there was no problems, so flew home. The next day, I did more runups including full power, etc. The first few showed #1 EGT high (+200) but only #5 going somewhat lower, then the issue "slowly went away" again. LOP mag checks at 75% power showed no problems.
I've talked with my mechanic, and I'm now on his schedule for about a week out. I'm not a mechanic, but here's my thoughts.
1. Not a probe related issue since #1, #3, #5 all showed related but different issues. Also CHT's tracked EGT's.
2. Not an induction leak, since they don't typically "fix" themselves?
3. Not a spark related issue, since there was no change on L or R mag. Also a later LOP mag check showed no problems.
4. A restricted flow in injector #1 that mostly cleared itself. Would that cause #3 and #5 to be affected? (Note that 1, 3, & 5 are all on the right side, if that is any clue.)
5. A restricted flow in #1, and [mostly] blocked in #3 and #5, until they became unblocked.
So, the above is my "non-Savvy Puzzler" for this month! Happy Thanksgiving to all. I'd appreciate any education and comments you might have.
