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Engine roughness and power loss when in IMC


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Hi there, 

I've just downloaded the SR22 G1000 and am mostly enjoying it, however, whenever I set the outside weather to anything IMC (in any sort of clouds/fog), the engine instantly, runs incredibly rough with the manifold, fuel flow, RPM and % Power fluctuating wildly. I've made sure the OAT is well above zero so it shouldn't be some sort of prop icing simulation but all the de-ice stuff doesn't help either. Even when I switch back to VMC after that, the engine stays rough. I fly the 22 IRL so it's not (or at least shouldn't be) an engine mismanagement issue.

Anyone got any ideas?

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I'm guessing this is due to performance limitations on your computer. I can't say this for certain without knowing the CPU usage, FPS, and specs of your machine. When clouds are rendered in X-Plane, CPU and GPU usage increases (potentially dramatically based on specs), causing FPS to decrease. The saturation of CPU usage prevents our engine physics model from running at full speed thus causing engine roughness. 

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  • 4 months later...

Hi Guys,

I have the same problems with the SR22 as Oliver describes: the engine power pushes up and down in an oscillating
cycle of half a second bucking and shaking the whole aircraft, let me call it the ghost.
It appeared mostly in high throttle conditions, but not always.
Interesting to read that it would appear only in IMC -
I mainly flew in scattered weather, but with your information I took some examinations and I can confirm.

On the picture you can see, the approaching clouds descended the FPS significantly and at 15 the ghost appeared.
Since I mostly fly in 3D cockpit view, I don't really notice the weather change,
but the cockpit-FPS decreased in the same way. That surprised me,
because from my experience the FPS in cockpit-view are mostly higher than those in environment-view.

Coop, about the root cause you said something  "performance limitations on your computer."
Well, I have an
- Intel-CPU i9-9900K with 8 cores running XP with 4.8GHz and a 16GB Main-RAM
- Nvidia-GPU GTX1070TI with 8GB-RAM
Do you think that isn't enough for your Torquesim SR22 1.2.2?

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1 hour ago, GerdS said:

On the picture you can see, the approaching clouds descended the FPS significantly and at 15 the ghost appeared.
Since I mostly fly in 3D cockpit view, I don't really notice the weather change,
but the cockpit-FPS decreased in the same way. That surprised me,
because from my experience the FPS in cockpit-view are mostly higher than those in environment-view.

Coop, about the root cause you said something  "performance limitations on your computer."
Well, I have an
- Intel-CPU i9-9900K with 8 cores running XP with 4.8GHz and a 16GB Main-RAM
- Nvidia-GPU GTX1070TI with 8GB-RAM
Do you think that isn't enough for your Torquesim SR22 1.2.2?

That CPU should definitely be sufficient, but isn't just an isolated single variable. Performance depends on lots of variables, including:

  • X-Plane graphics settings
  • Scenery and other plugins in-use
  • Other software running on the computer

If the CPU is saturated and the physics thread is blocked from running at full rate, the engine will stutter.

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Thanks for your response, Coop,

but I'm not really convinced of your claim "the CPU is saturated and ..."  to be the root cause, because the CPU runs with only 25% load.
I closed all other software such as Firefox, GIT, third party weather, or any other tools,
but I can't notice a change in that 25% load number.
In the picture you can find as well a screenshot of the plugins. So, let me know, if you guess which could be responsible.
The scenery is standard laminar. As you can notice in my picture from Nov/17th there are only a few buildings; hence no challenging scenery.

 

20211124_load_cpu_and_more.PNG

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Based on my experience the root cause is close to "clouds", as Oliver already mentioned. So I played a bit with the graphics levers.
"Number of World Objects" doesn't change anything. It mainly controls the density of the groundbuildings.
"Visual Effects" does something:
The screenshot with the low 15 FPS from Nov/17th was taken with 75% setting (No 1 on the picture).
The screenshot with the well 27 FPS from Nov/23th was taken with 50% setting (No 2 on the picture).
This leads to picture No 3 with 27 FPS, but somewhere along the way from POM to SAGER iaf (Aproach-KSNA-I20R) its engine starts stutter again!
How can you explain that? Still with CPU-Performance?

20211124_Graphics_Settings.PNG

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Which GPU is installed for pictures 1, 2, and 3 in your last post?

The engine model, assuming the engine isn't damaged (you can try performing maintenance via the SR22 Maintenance tab), as it only approaches near clouds, this signifies significant performance anomalies with the machine. Based on the screenshot sent, it does seem that the machine is GPU limited. Based on both GPU options, even the 1070 should be sufficient.

If you can, send over a log.txt file from the sim from when it is doing the stuttering and that should help give a better picture on what is going on.

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The RTX 1070 Ti GPU is installed for all the documentation.

To your assumed engine damage, I can tell you that on the first flight with stutter I didn’t discover any abnormalities in maintenance report.
Today there is a report which should to be cleared and adjusted, before we continue with the examination around the stutter issue, o. k.?
In almost all of the 7 Inspection parts I found:
“The following services needed to be performed:
ENGINE ENTRIES
SYSTEM ENTRIES”
The history I found in …/Output/SR22/logbook

But I don’t find anything about “ENGINE ENTRIES“ in the documentation how to fix.
Where can I find a documentation about that?
But I found 3 entries about that in this forum. Let me first see, what’s going on there …

 

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1. Issue with Engine Oscillation SR22 G1000 After Take Off:
Not really something new, but that my stutter appears as well already on the first flight after Take Off without clouds ... (interesting ...)

2. CHT overheat issues with 1.2.1 Release:
Coop: "That is what it shows when there isn't anything being caught on the inspection (nothing under Engine Entries or System Entries)"
mtbparker: "Ah!  Ok.  I was interpreting it to mean there might be something in the engine intakes."

That is my interpretation as well, but if there hasn't anything to be done, isn't it a bit misunderstandable?
If I find the note "Replaced fuel filter element" that tells me: somebody has already replaced the fuel filter system.
But what is the sense of that for me? If I would find: "fuel filter element to be filled" it has an appeal function with an action for me.
If fact, that could be a reason for stutter, when the fuel filter is congested. Would be a good programmable aspect in future!
Further to me:
Any kind of leaning, pitot heat switch or ICE switch doesn't change stutter ...
I always used SR22 so far, not SR22TN.
Versioncheck: "TN_Record.txt" is empty, "TN_State.txt" has information; both files are dated from the first use with Vers 1.2.1.
No difference found between both versions.

3. Oxygen Switch not working
Nothing what can help me.

Summary:
1. stutter problem: no further help found
2. maintenance: meanwhile I’m convinced that “The following services needed to be performed:” tells me more or less, that there has already been done something, hence no appeal for me.
If I had been prompted to do something, I would expect the word need in present tense not in past.
To get your clear opinion, Coop, I’ll attach my latest SR22 logbook.
Do I have to do something for engine to repair, and if yes, what and how?

 

SR22_logbook_20211125.zip

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Before deleting NA_Record.txt and NA_State.txt:
“Unfortunately,” I couldn’t reproduce the stutter even with increasing IMC intensity from SCT, over BRK to OVC. I started the flight both with running engine and cold and dark last week and today, but couldn’t reproduce a similar situation, except, when I lean too much. But that stutter is significant higher than the coincidentally happened one, which I described above.

After deleting NA_Record.txt and NA_State.txt:
The new NA_State.txt contained different text, but the maintenance information kept the same.
Regarding stutter that change delivered no additional information.

I’m going to continue my training with that aircraft for a while, and since I can capture a new stutter, I’ll post the log.txt.

Gerhard.

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