EGT lag in one cylinder after start

With no lane faults I would think a clogged injector sounds right.  These engines are run in at the factory, so your injectors have had old fuel in them for at least two years.  I believe others on this forum have experienced this also with stored engines. I don’t think Rotax has an approved cleaning procedure so you may have to replace them. You could swap those two injectors with another cylinder as a test before buying anything.

Thank you for the reply, Jeff, that makes sense.  I actually did get two lane faults during the first 2 minutes when the #2 cylinder wasn't firing properly, but both cleared after cycling the lane and I got no more faults after that.   The Dynon data log shows those faults, but unfortunately doesn't show what triggered them.  But all other engine parameters where normal except the #2 EGT.

I'll do some research on cleaning the fuel injectors, but I'm surprised Rotax does not have an approved procedure for that since it's such a common task in engine maintenance.   Do you know if there's anything different about Rotax fuel injectors that drives this?

I also thought I might try running the engine again first, thinking that perhaps a little more run time might help clear out any residual gumminess from old fuel in the injectors (especially since I'm burning mogas with ethanol). 

I’m betting the injectors are made by an automotive injector manufacturer and are very similar.  And while Rotax does not endorse or approve any fuel additives to clean injectors, Chevron fuels already have Techron added.  So adding a Techron concentrate to 5 gallons of fuel (in the ratio as specified by Techron) for some extended ground runs would seem to me to be a reasonable thing to do. You could also call one of the major Rotax Service Centers and see what they recommend for partially clogged injectors.