#3 EGT Misses Peak

[petehowell]

Hello,

I use EGT to lean my O-320 aggressively.  I have certain settings where I know the EGT'S peak and then go LOP.  Yesterday all the cylinders accurately reported the peak except #3.   I could manually watch it peak and go LOP, but the lean mode would not catch it.   It caught the peaks of 1,2 and 4 just fine.   I repeated this 3 times on the flight.

Any thoughts? - I'll fly this weekend and see if it happens again.

Pete

 

[dynonsupport]

Pete,

What software version are you running on your EMS and is it a D10 or D120?

 

[petehowell]

Hi Mike,

I have a D10 and I have the latest firmware. Only recent change is uploading new checklists into the DSAB Linked D10A.

Cheers,
Pete

 

[dynonsupport]

Pete,

Did you stay in lean mode as you cycled up and down, or did you exit lean mode each time you tried to re-find peak?

We haven't seen this before so we're trying to catch it, and the more info you can give us, the better.

 

[petehowell]

Hi Guys,

I recycle the lean mode if I know that I've gone more than 15 deg past peak, and then re-lean.  That said, I think this may have been an engine problem.   I saw the same issue with #3 on a long XC yesterday.  I suspected an induction leak, so I pulled the cowl and and tightened up all the induction interfaces on #3.   Flew this morning and #3 was peaking right where I expected it.  

The EMS was not catching the peak b/c it was peaking much earlier than expected.  Sorry for the false alarm.    This does demonstrate the value of 4 cyl CHT/EGT monitoring and getting to know your engine.  The EMS was working perfectly.

Cheers,

Pete

 

[dynonsupport]

Just to clarify - do you think that cylinder 3 was already on the way down from peak when you entered lean mode?

 

[petehowell]

Yes, I do. I flew again last night and all is well.

I kept expecting a peak and never got it, b/c it had peaked so much earlier than expected. Sorry for the false alarm. I should have paid better attention.

Pete