MSFS 2024, engine spike issues at KIAH, HOU

[virtuali]

I just spent a good 60 minutes flying the 77L around KIAH with couatl.exe either running or not.  Can confirm engine spikes occur with couatl.exe running and cease with it shutdown.  Certainly odd, but it's consistent and repeatable.

I loaded the 77L at FSDT KIAH, and couldn't replicate it, see the video:

I read on PMDG forum, at least two users said it was fixed by clearing the airplane WASM cache, as suggested by PMDG. Now, you said you flew for 60 minutes, I only flew for 8 minutes around the airport so, does it mean I need to wait longer before the problem appears, or it should have already happened during that time ?

Note that, I had the Winwing software running, but I had all the various Winwing devices disconnected, so the software was likely not active. That's because someone suggested it might be related to it, but I still don't understand how it can also be related to KIAH.

[TheDavid737]

I’m not sure it’s specifically related to FSDT IAH. I think it’s just something about the Houston area. I flew into IAH last night from FLL and sure enough on final starting about 10 miles out and around 6000ft engine spikes started occurring killing the auto throttle in the PMDG 737. As soon as I killed Couatl, problem stopped. Restarted Couatl on the ground and all was good.

I followed the recommended WASM cache clearing from the PMDG forum and that didn’t resolve anything. Tried it it in both the PMDG 737 and the ifly max 8, both of which I’m seeing the problem.

[virtuali]

I’m not sure it’s specifically related to FSDT IAH. I think it’s just something about the Houston area.

That would remove an element of doubt then: I have FSDT KIAH installed and since I also saw users with this issue with and without it, I tested with, assuming it won't make any difference.

I flew into IAH last night from FLL and sure enough on final starting about 10 miles out and around 6000ft engine spikes started occurring killing the auto throttle in the PMDG 737. As soon as I killed Couatl, problem stopped. Restarted Couatl on the ground and all was good.

Do you have it if you start a flight at KIAH instead ?

[TheDavid737]

Yes I do also have it if I start at KIAH as well.

I’ll also add it’s not every flight. Some flights there are no issues, some flights the spiking is minimal, and others the spiking is so bad that over speed is inevitable. The only thing that changes that dynamically is weather. Not sure how weather + Couatl could impact engines but I’m trying to think of anything.

[virtuali]

Not sure how weather + Couatl could impact engines but I’m trying to think of anything.

That's what I don't understand either. As a general rule, GSX never change anything in the airplane status, it never writes to airplane variables (standard or custom), it only reads them.

The one and only notable exceptions are:

- during pushback, from the moment the crew says "bypass pin inserted" up until it says "bypass pin removed", the airplane position and heading is controlled by GSX, just position, heading and steering, nothing else.

- IF the airplane uses a standard fuel system (surely not PMDG then, since they are all flagged to use a custom fuel system), during the refueling, GSX will increase the fuel quantity. This basically happens only with default airplanes, and not even all of them.

Those are the only places where GSX ever writes something on the airplane. And of course, never in flight.

Fact I cannot reproduce it yet, seems to suggest there must be something else (another add-on) that it interacts with GSX, and that one is causing the engine spikes on the 777 or the A/T disconnect on the 737, so the effect stops when you close the Couatl engine because that addon might have realized GSX is not running anymore, so it stop whatever it was doing, so it would be useful to know which other add-ons you are running.

[szln6z]

Hi Umberto, I very much appreciate you taking the time to check this, and even posting the video of your test.  I just deleted the WASM for the PMDG 777 and tried a flight departing KIAH (I do have FSDT KIAH installed).  Unfortunately, the spiking commenced pretty much immediately.  I tried switching weather to Clear Skies (not Live) and it made no difference.  I also discovered that the spiking occurs even with A/T completely off (manual thrust).  As per last time, I flew around KIAH at 4000 feet starting and stopping couatl64_MSFS2024.exe; spiking occurred only with couatl running as before.
For now, I have added a shortcut to Couatl64_boot.exe onto my desktop; whenever I fly into KIAH, and I will just kill couatl with task manager until I'm on the ground, and then run Couatl64_boot.exe before taxiing to my gate.

[TheDavid737]

Hi Umberto. Here is my full list of addons with the exception of airports used via addon linker.

here is my list:
Aerosoft CRJ
Dirty 30 and Liveries
Elevatex Bridge
Fenix 319,320,321 and Liveries
FSLTL Traffic Base
FSUIPC 7 WASM Event Module
ifly 737 Max 8 and Liveries
IVAO_MIL
Miltech MH60
Mobiflight Event Module
Navigraph EFB Charts App
Navigraph EFT Simbrief App
Navigraph NAV Base
Navigraph Nav Jepp
P42 Chaseplane
PMDG 738 and Liveries
PMDG 777 and Liveries
Winwing WWTWSAM
Boris 737 Audio
Boris 777 Audio
Boris CRJ Audio
GSX Pro
GSX World

[TheDavid737]

Hi Umberto. So another update. Myself and szln6z connected on discord and actually compared our list of addons. Szln6z went through the efforts of testing each addon one at a time we both found the same results below. I will let szln6z speak for themselves but in my case, we narrowed it down to FSLTL and GSX. When Coualt and FSLTL are installed/running at the same time, we get the engine spike issue. As you know when we disable Couatl via task manager, the issue goes away. The new part is when we uninstall or remove FSLTL from the community folder, the issue also goes away, even if we keep Couatl running.

So in short:
GSX alone in IAH area = no issues.
FSLTL alone in IAH area = no issues.
GSX + FSLTL in IAH area = engine spiking issue.

***Update after posting this information in FSLTL discord***
From BirdmanRS: So somehow the AI models/animations/soundpacks in FSLTL Base Models, injected by some other tool, are modifying the user controlled aircraft?  Interesting.

My response: That’s what seems to be the case. The strangest part is it’s only in the area of KIAH that we have found so far (both default and 3rd party scenery) and only when GSX (Couatl) is running at the same time, and only for some users. I did add these test results over on the FSDreamTeam forum post we have going so hopefully Umberto will have some ideas as well.

From BirdmanRS:I can confirm there is absolutely nothing in Base Models that is location specific.
If you find out more, let us know.

[virtuali]

I tried with FSLTL as well, had one UAL model placed in the hangar, and couldn't see any spikes so, maybe, it's not "just" having FSLTL installed, but might depend on which model, since the one selected is chosen at random amongst all the available ones in the UAL livery.

I might try making a change to the KIAH code to spawn the model with its simulation completely disabled, I'll let you test a changed file soon.