09 Speed 3 stumbling while driving...with logs!

[liquidefex]

Within the last 2-3 months I have noticed an intermittent stumble while driving that seems to be getting worse, and I think accompanied by a sulfury smell from my exhaust....

Check out the logs I've posted, I think my AFR is f**ked and that is throwing everything else out of whack because I have a bad O2 sensor or a totally clogged cat.

Driving was semi-normal today, then a large bunch of stumbles around 550s to 590s mark where you can see lots of things go haywire, I'm just not sure what went haywire FIRST and caused trouble everywhere else.

If that is the issue I'll probably go full high flow cat exhaust from edge, just hoping for a few opinions before I squeeze the trigger on it.

logs are attached! also a screenshot from that same timeframe as a little visual...labels are on the left except for:

red = absolute load
light orange = accelerator pedal position
dark orange = wastegate control solenoid duty cycle

 

[Awafrican]

Have you tried anything diagnostic? Like checking plugs, cleaning MAF, boost leak check? You know the absolute basics that searching for these symptoms would tell you to do

 

[liquidefex]

yeah! definitely could've been more explanatory in my first post sorry about that.

plugs look good, cleaned maf was the first thing i did, and have not found or heard any boost leaks.

stumble also may not be the best word as a descriptor either...it's more like im cruising along at say 2500rpm, then the power just falls off momentarily, like the car wants to go back to idle. then i let off the accelerator pedal, press it again, and it's hit or miss whether or not the power comes back right away. sometimes i have to stay off the accelerator for one second, sometimes its a few seconds, but then i get back on and it comes back.

other times, when i get back on the gas there is significant bucking, almost like the throttle is being given really aggressive inputs at random?

 

[Awafrican]

Appreciate that sulfur smell could be cat, it also could be fuel pressure sensor / fuel filter / old trans fluid.

One way to check fuel pressure would be to do the PRV test with a hot engine.

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@Easter Bunny thoughts?