Engine Monitor Data - Troubleshooting Thread

[Marauder]

Hi All,

 

Brett's graphics from his JPI 830 revealing his stuck valve situation was a great example of how to interpret the data. Any of us who own these marvels are certainly impressed with the information it displays, but also are overwhelmed as to what it all means. I thought I would start a thread on examples of engine monitor data and what it meant. Please feel free to show other examples, because I am here to learn too! Brett -- you think you could drop your example here?

 

My first contribution is a fouled #2 cylinder plug on the left mag. You will notice that the #2 EGT temp (yellow arrow) was elevated right from engine start -- something I missed because a) I wasn't looking at the EGT temps and the engine was running smoothly.

 

You will see when I took the rpm up to 2000 to do the run-up, the red arrow points to the dip in EGT temp and of course, now I felt it. I aggressively pulled the mixture at the blue arrow and then did a left right left mag check as indicated by the white arrows.

 

[scottfromiowa]

Good stuff. Great idea for a thread.

[bnicolette]

Chris what a great idea for a thread.

 

I attached two sets of pictures.  One is from 6/24 and the other is from today 7/15.  Both have full screen shots of the entire flight and then also a zoomed in picture of the first 5 minutes.  My issue was the #1 exhaust valve was sticking due to carbon build up on the guide (morning sickness).  It also appears as though the valve was starting to stick at the end of the flight too?

[bnicolette]

So, right after I had my #1 valve guide reamed (which is working perfect by the way) my #2 EGT started showing similar symptoms right after startup.  Within a minute of starting I would again get a slight roughness which now immediately pulls my attention to the JPI EGT readouts and sure enough the EGT was dipping on one cylinder.  I didn't want to jump the gun so I've been watching it closely for the last couple flights after startup and each time I got the same thing.  So, off I went this morning to Aero Engines of Winchester in Winchester, VA to get them to have a look.  Indeed the #2 valve was tight in spots so he reamed it out and got quite a bit of carbon out of the guide.  The whole process was done in 1.5 hours.  I landed at 7:40am and was airborne by 9:40am.  Those are great folks at that shop and I can't recommend them enough.  Attached is a picture of a startup and you can see right around the minute mark the #2 EGT dips down and as is quite common with a sticking valve the manifold pressure increases.