Super Wide EGT Spread? Engine Monitor data

[33UM20C]

Hey guys this post is sort of an addition to my other post here but looks like the discussion evolved into other things so I'm going to start a new one with some updated info and new questions for you all. 

As the last post states I was having some engine roughness I.E vibrating intermittently after it was hot, as well as very high EGT's on Cylinder #1. I changed the spark plugs even though they all looked fine, now running Tempest Massive ones. It seemed to fix the roughness as the engine runs smoother now, I'm also a stickler about aggressive leaning (just in case). 

My possible problem is a very wide EGT spread due to C#1 having a very high EGT.

Reading this article here makes me want to shrug the situation off as a normal inconsistency and that I'm overthinking this whole thing. If you agree please tell me so. 

Here's the data from my EDM 830:

Here you can see my takeoff just before where the curser is when the RPM in green shoots up. After a minute of so I transfer into a cruise climb but don't lean yet, C#1 in red EGT's continue to climb much higher and faster than the other cylinders. Its not great after that running at least 150-200 deg hotter than the others

I wont include a CHT graph because its exactly what you should see, spread of about 60 deg F on CHT and C#3 the hottest due to its positioning.

Here's the next day:

As you can see C#1 peaked at 1670 deg with mixture rich on takeoff. It stayed hotter most of the time and had more dramatic rises and falls.

Next day, I replaced all plugs with tempest massives and here is the data:

Looking better, cylinder 1 is higher but this can be chalked up to placement of the probe and general inconsistency. I was happy with this flight and its temps. Note that the sharp arm rises for 1 minute at a time were post maintenance WOT run ups.

Here's the last day I flew:

All the peaks on the right were me doing touch and goes. Things look okay on the touch and go side but over in the cruise and pre maneuver side you can see the curser on a particularly wide EGT spread. That curser mark was probably mixture rich because I was maneuvering.

My questions for you guys:

1. Am i crazy or is this EGT spread a little too high, with peaks too high?

2. Is there a problem here or can I chalk this up to be placement errors, probe errors and general inconsistency?

For reference here is a cruise flight from the previous owner:

 

Some things to note:

• This info was pulled from a JPI EDM 830
• Aircraft: 1963 Mooney M20c IO-360
• Passed annual last month, they borescoped the cylinders and said they were fine
• Changed spark plugs last week
• Brand new baffling
• 600 hrs. on the engine and good compression 72/80 on C#1

Thanks guys!

[Shadrach]

Did you do an in flight mag check as recommended in the other thread?

[33UM20C]

Yes, It ran rougher as expected but no cylinder went offline and temps seemed to stay relative. 

[Shadrach]

19 minutes ago, 33UM20C said:

Yes, It ran rougher as expected but no cylinder went offline and temps seemed to stay relative. 

your engine should run smoothly on one mag unless leaned aggressively.

So I’m looking at the data you posted. EGTs look very normal initially. Then around 16:00 there is a trend change for #1.  The odd thing is that the trend change does not correlate to fuel flow changes. Is the spike at about 17:40 your inflight mag check?

 

[33UM20C]

On that flight I can specially say no, it was not. Only because that was before I owned the plane. Its been a couple flights and I've forgotten at what point / when I did the mag check. 

But what you pointed out is what annoys me the most. Its perfect for some time then with no FF change or RPM change the EGT's get very high...

I did not fly this flight but in checking every other readout the EDM shows nothing else spikes like the EGT's do here. I guess that's what I want to explain.. Why the wide spread when the engine heats up?

[Shadrach]

12 hours ago, 33UM20C said:

On that flight I can specially say no, it was not. Only because that was before I owned the plane. Its been a couple flights and I've forgotten at what point / when I did the mag check. 

But what you pointed out is what annoys me the most. Its perfect for some time then with no FF change or RPM change the EGT's get very high...

I did not fly this flight but in checking every other readout the EDM shows nothing else spikes like the EGT's do here. I guess that's what I want to explain.. Why the wide spread when the engine heats up?

Still looks ignition related to me. To be clear, you don’t have a super wide EGT spread, you have a single cylinder that trends as it should until an unknown event causes it to runaway from the rest.

[Aerodon]

What are the CHT's doing?  Carb engine right? Induction air leak causing a leaner than other cylinders.  Look carefully at gaskets the rubber joint in the induction, goofy things like those old 'standby vacuum systems'.   On an injected engine I'd be looking for a partially blocked injector.

Don

 

 

[Shadrach]

It looks to me like he had a flakey plug. No intake leak is going to generate a 1670° EGT reading based on mixture alone. You need an energy dense yet slow combustion event to do that…i.e. single point of ignition and flame propagation.

After revisiting his numbers, I think the new plug has solved the ignition issue. The remaining  spread is likely due probe placement as his F/A spread looks pretty good for a carbureted engine.

[Shadrach]

@33UM20C

If you’re still uncomfortable, I’m happy to ride right seat and put a second set of eyes on it in flight. I live just southeast of the FESAN INT for ILS LOC 23. Shoot me a DM if I can be helpful.

 

[33UM20C]

@Shadrach That would be great. I'm going to be out of the country for another week. When I get back lets set something up! Il DM you as soon as I'm home.