66’ E cyl temp spread...

[Nukemzzz]

At a steady 24x2100 power setting I’m seeing: 345, 343, 327, 305 (I think cylinder 3 was the cold one). The cold cylinder also had the highest exhaust temp hinting that this cyl maybe has a higher flow injector.  This was a training flight and so the lean procedure was the simple...lean till misfire and then turn in a few times  

Does this temp spread seem normal?  Not sure if I should be concerned.  Might be just variation in the thermocouple readings. Might be the cooling is better on 3. 

[carusoam]

Got any JPI data to go with that?

-a-

[MikeOH]

20 minutes ago, Nukemzzz said:

At a steady 24x2100 power setting I’m seeing: 345, 343, 327, 305 (I think cylinder 3 was the cold one). The cold cylinder also had the highest exhaust temp hinting that this cyl maybe has a higher flow injector.  This was a training flight and so the lean procedure was the simple...lean till misfire and then turn in a few times  

Does this temp spread seem normal?  Not sure if I should be concerned.  Might be just variation in the thermocouple readings. Might be the cooling is better on 3. 

Looks to be about a 40 degree spread.  I looked at about half a dozen of my flight over the last two years and I'm seeing: 20 to 25 degree CHT spread.

[Nukemzzz]

10 minutes ago, carusoam said:

Got any JPI data to go with that?

-a-

I’ll see if I can pull it. It will only have cyl, exh, temps and and fuel flow. 

[carusoam]

A few steps... but it is worth it...

get the data from the JPI, onto your laptop... upload the data to savvy.com...

Find the share button... push it...

Copy the link... put the link here...

CHTs are 50% heat generation, and 50% cooling...

If all the EGTs are the same... probably a cooling challenge...

If the EGT is cold... and the CHT is cold... the cylinder may not be getting any fuel...   

fire up the data collecting machine!

 

PP thoughts only, not a mechanic...

Best regards,

-a-

[Ragsf15e]

Jeez, I usually have a bigger spread than that with no issues.  Typically number 3 is hottest and 1 coolest as its right up front.

Lean very slowly through peak and see what order the cylinders peak.  When ROP, usually the hotter ones are the leanest although in my case 4 peaks first and is usually slightly cooler than 3.  LOP, the last one to peak is usually hottest.

[gsxrpilot]

45 minutes ago, Nukemzzz said:

At a steady 24x2100 power setting I’m seeing: 345, 343, 327, 305 (I think cylinder 3 was the cold one)

This data really doesn't say anything about anything. It could be perfectly normal, or it could be symptoms of a problem. But we need more data to know. 

Run the Savvy Flight Test Profile and post the data here.

[theflyingdoctor]

I’m having the same problem with my 3rd cylinder. I’m breaking in the new engine so I’ve been skeptical if that spread (40-50 degrees on the CHT) might be an issue. But from time to time i have the misfiring/detonating sound which is concerning that there could be a problem. So far we have checked compressions twice, the injector lines, injector valves,  cleaned the spark plugs, checked to make sure sparks are adequate, swapped spark plugs on cylinders, replaced  fuel divider, checked induction tube, and even checked the mag and the mag timing today and still haven’t found the problem. Not sure if pulling data from my JPI monitor would give me any additional info since engine is about 20 hrs old. Wondering if anyone has had anything similar to this in the past. 

[carusoam]

Welcome back Doc!

where have you been?  Long time no see... 

Lets see if you can get your JPI data linked here...

It helps to have the JPI set up to collect data as quickly as possible...

And follow the guidelines for running the tests... as outlined by Savvy...

When doing a run-up... allow for plenty of time to allow the engine to stabilize and collect multiple points of data...

Plan on starting a new thread too... this one is going to be long and complex with the OP’s current challenge...

Pp thoughts only not a mechanic...

Best regards,

-a-

[PT20J]

Also, keep in mind that you will get variation depending on probe type. The hottest portion of the cylinder head is near the spark plug, so spark plug gasket thermocouples typically read about 40 F higher. If you use a gasket thermocouple on the factory bayonet probe it will typically read about 20 F low. Spreads can also vary with mixture.

Skip

[PT20J]

10 hours ago, theflyingdoctor said:

But from time to time i have the misfiring/detonating sound which is concerning that there could be a problem.

Can you describe this? Is it really a sound or more of a vibration? What power settings (throttle, prop, mixture) are you using when it occurs? 

A continuous misfire will cause a very noticeable roughness. An occasional miss would be more of a shudder. The most common cause would be ignition related. 

Detonation (absent fuel contamination or some mechanical issue) would require max power with a combination of mixture near peak EGT and very high CHT. 

Skip

[Nukemzzz]

To be clear, the only indication of trouble that I have is 350F is bigger than 300F and 50 is more of Fahrenheits than I can count on my hands. The engine runs strong and good.  I'm mostly suspecting a that one probe needs to be reseated or something.

I'll check back in when I sort out how to pull the data from the JPI.

[Ragsf15e]

27 minutes ago, Nukemzzz said:

To be clear, the only indication of trouble that I have is 350F is bigger than 300F and 50 is more of Fahrenheits than I can count on my hands. The engine runs strong and good.  I'm mostly suspecting a that one probe needs to be reseated or something.

I'll check back in when I sort out how to pull the data from the JPI.

Honestly, 50 degrees cht difference on an io360 with the vintage cowling / cooling setup isn’t much.  If it’s making normal power and smooth, I wouldn’t worry about it at all.