Engine data analysis

[Cruiser]

What is happening with my #1 EGT ? https://www.savvyanalysis.com/flight/2521604/58162588-b8ab-431c-9f95-85e72e0d6aca

JPI 830

6000'

60% power

LOP -20°

Outside temp 57°F

 

thanks, 

 

[Bob - S50]

Be more specific please.  Are you talking about low EGT at idle?  Something else?

[Rick Junkin]

2 hours ago, Cruiser said:

What is happening with my #1 EGT ? https://www.savvyanalysis.com/flight/2521604/58162588-b8ab-431c-9f95-85e72e0d6aca

JPI 830

6000'

60% power

LOP -20°

Outside temp 57°F

 

thanks, 

 

I'm not an expert by any stretch of the imagination, but I read a lot and it appears to indicate a failing exhaust valve. https://www.avweb.com/news/savvyaviator/191197-1.html

Scroll down about a page to the graphic that shows the EGT data.

Do you or your mechanic have access to a borescope? I'd want to get a look at the exhaust valve in #1. My guess, again just from referencing what I've read, is that you will see something other than a symmetric "burnt pizza" pattern on the exhaust valve, and possibly some hints of green on one side of the valve. Probably not something to delay or ignore.

Cheers,
Rick

[carusoam]

I see the oddity right after start-up...

And the bit of saw-tooth during the flight...

As I expanded the graph... the saw tooth was very similar to other lines, More a phenomena of little data spread out over longer time...  less likely to be the saw tooth of sticking/non-rotation of valve issues...

 

Got any other flights to compare to?

The oddity after start-up shouldn’t be there.

Start-up is usually pretty rich... to get a cylinder to run cooler... may take extra fuel going there... or a spark not firing?  

Plugs not firing in cruise, usually run hotter EGTs as fuel burns leaving the exhaust valve... we are not seeing that either...

 

Did you get a chance to mess with the mixture when you saw the cold cylinder after start up?  Did you lean close to 2gph on the ground @1k rpm...?

Which plugs do you have?

PP thoughts only, not a mechanic...

Best regards,

-a-

 

 

 

 

 

[jaylw314]

Change your data interval to 1 per second.  That will help distinguish between "sawtooth" and "square" signal changes, with the latter being more likely to be a bad connection/sensor.

[One Whiskey Hotel]

If you change your data sample interval from 6 seconds to 1 second, be ready to download your engine monitor more often if you want to review everything intensively. All depends how OCD you are and how much time you have for such neuroticism.

[Rick Junkin]

Looking at the details at the bottom of the data, the sample interval is 2 seconds. I believe that's the best granularity that a JPI 830 is capable of, correct?

@Cruiser, did you get any further toward an answer to your question?

Cheers,
Rick

[Awful_Charlie]

On 6/9/2018 at 3:43 AM, Junkman said:

I'm not an expert by any stretch of the imagination, but I read a lot and it appears to indicate a failing exhaust valve. https://www.avweb.com/news/savvyaviator/191197-1.html

Scroll down about a page to the graphic that shows the EGT data.

I don't see a great variation there - I think this looks pretty normal.

Here's a failing #3 exhaust valve  with a 4 second sample interval (on the ground, 1000-1200RPM, so the fluctuation in the cruise would be around twice the frequency)

According to the documentation, you should expect the variation to maybe be installation specific, with EGT probes further from the cylinder head showing less of a variation - however after swapping a couple of bits of exhaust with unmatched pre-drilled probe holes in the past, I have a feeling that effect may be exaggerated somewhat

On 6/13/2018 at 4:27 PM, One Whiskey Hotel said:

If you change your data sample interval from 6 seconds to 1 second, be ready to download your engine monitor more often if you want to review everything intensively. All depends how OCD you are and how much time you have for such neuroticism.

It only takes a few seconds to grab the data (I normally download the JPI data after the last flight of the day - the USB stick is on the keyring!) You don't need to do anything with it, but when you find a problem you have something to compare against - isolating a problem without any reference is more difficult.

With a 6 pot engine, most of the options installed, a 4 second interval, the old EDM800 I have can store around 8 hours of flight - I believe the EDM x30 models have a lot more memory (although some of this will be used by the GPS options)

[Cruiser]

21 hours ago, Junkman said:

Looking at the details at the bottom of the data, the sample interval is 2 seconds. I believe that's the best granularity that a JPI 830 is capable of, correct?

@Cruiser, did you get any further toward an answer to your question?

Cheers,
Rick

You are right, sample rate is 2 seconds. No answers. It seems weird that the oscillations will come and go on this single cylinder. I had discounted electrical because of that, but maybe I shouldn't? 

[Bob_Belville]

I have a EDM 930 and leave the sample rate at 1 sec. I download the data to a USB stick pretty frequently and upload to my laptop and to Savvy. file sizes are not an issue. When something goes amiss it is very helpful to have history and Savvy wants the shortest sample rate the EDM can provide. 

[gsxrpilot]

3 hours ago, Bob_Belville said:

I have a EDM 930 and leave the sample rate at 1 sec. I download the data to a USB stick pretty frequently and upload to my laptop and to Savvy. file sizes are not an issue. When something goes amiss it is very helpful to have history and Savvy wants the shortest sample rate the EDM can provide. 

Ditto... EDM 900

I'm thinking if I ever sell her, a full and complete history of every flight I've ever made on the SavvyAnalysis site will be very useful for buyers wanting to evaluate my engine management and type of flying. #nothingtohide 

I also use the Savvy site when updating my pilot logbook. I'm terrible about logging flights but I can always go to the Savvy site and it's got all my flights with origin/destination/time/etc.

[FloridaMan]

Just as a note, the $30 borescopes from Amazon that use your phone as a display work better than what you would’ve paid a lot for just a few years ago.