boscomantico wrote:
But what is interesting is that the spread“ starts getting bad only after the leaning. Before, it is decent.
I’m not sure what you mean by this. In my initial post you can see the before and after lean, and before (during climb) it’s definitely bigger. The last graph I shared today is 100% rich.
At 00:11:30, all four EGT values are very similar. The are also in the normal range (1250-1300)
At 00:12:00, i.e, after you change lower setting, you get that huge „spread“ on the four EGTs, because #1 and #2 increase inly slightly, but #3 and #4 increase much more.
I would check the inlet etc gaskets.
boscomantico wrote:
At 00:11:30, all four EGT values are very similar. The are also in the normal range (1250-1300)
At 00:12:00, i.e, after you change lower setting, you get that huge „spread“ on the four EGTs
At 11:30 is when I commence my takeoff roll, and then 12:00 is during climbout. So that’s not a lower setting. It’s high power, high pitch angle.
dutch_flyer wrote:
Here’s an initial climbout followed by a shallower, longer climb at higher speed:
From that I’d guess it is not baffles. What puzzles me still is the cylinders marching in pairs on such spread. As said b4, I’d check the innert of the gaskets at the carb, whether there is some partial blockage or hindering the inlet air flow. Is there any silicon slubber visible at the carb? Compression on all cyls is ok?
The correlation does seem to be the initial Vy climbout period, which is also the period where the #3 CHT is higher.
MichaLSA wrote:
As said b4, I’d check the innert of the gaskets at the carb, whether there is some partial blockage or hindering the inlet air flow. Is there any silicon slubber visible at the carb? Compression on all cyls is ok?
Not sure. It’s in for annual in about 5 weeks, so I’ve sent this to the shop to also have a look.
@dutch_flyer maybe I have missed it, but can you say if there was any throttle movement during those graphs (I mean in flight, ie start of t/o roll does not count) and if so, correlate them to the graphs?
Antonio wrote:
can you say if there was any throttle movement during those graphs
Here’s RPM and MAP from the same timeframe:
There’s an issue with a jumpy MAP reading because it’s currently missing the factory snubber to even out the reading. This will be corrected at next visit.
So the abnormal split in Cyls #1 and #2 occurs at the time of throttle retard around 00:14:50
Those symptoms would be consistent with an induction leak in #1 and #2 (making them too lean upon throttle retard, as Peter said, check gaskets, hose clamps, seals… for any potential leaks in induction pipes) .
Also make sure your numbers are not crossed so you aim for the right cylinders: it is not unheard of to see that cyl sensors are connected to wires for a different cylinder, providing misindication. Easy to check with a heatgun pointed at the exhaust underneath the sensor and seeing the corresponding rise on the indicator.
