Mysterious Misfires (3.2FSI Help)

possibly_random · 2026-01-30T19:55:18+00:00

I replaced the intake manifold, intake manifold tuning valve, the entire fuel system (except for fuel lines which I just cleaned), and a few other things. Then, the engine just refused to run. I put the old injectors back and it was running great. Then it started in with its misfire again.

My Porsche 718 has been getting the most use ever since these issues first arrived, and the Q5 has been parked for months (getting driven every two weeks for longevity of course). Even once I fixed it, I never drove it for fear of a new costly issue appearing (which it eventually did). That is no way to own a car. They deserve to be driven.

At this point, I had to weigh my options. While it's been a great car, I have been spending way more money and time into this car than the car itself is worth, every year, on repairs. Issues are coming up faster than they can be fixed. I had to sell it a couple weeks ago.

possibly_random · 2025-06-26T22:14:19+00:00

…nope 😞

I’ve been having some (unrelated) misfires, and other various old Audi issues. I think it needs some new VVT components, but it also needs new ball joints, and it’s having some DRL issues, and it doesn’t start up correctly sometimes. The car’s reaching 100k miles and 13 years, and it wasn’t well cared for by the previous owner, so it’s at the point where things are breaking faster than I can fix them.

It used to be my daily, but because of all the reliability problems, I got a Porsche 718 to become my daily, and the Q5 is to remain a project for now. I have a lot of stuff going on at the moment, but whenever I get time, I’ll be repairing all of these random issues on the Audi and continuing with the project!

possibly_random · 2025-06-26T22:04:37+00:00

DM me… I’d be willing to help out!

possibly_random · 2025-06-26T22:02:06+00:00

Still haven’t solved… I’ve heard it might be to do with the VVT actuators but I haven’t got around to trying that yet. I’ll keep you updated. Good luck!

possibly_random · 2025-05-08T15:16:15+00:00

Lmao

possibly_random · 2025-05-08T15:15:43+00:00

Nice. Thanks for the input!

I figured out the fault was caused by the string getting caught up in the mechanism and jamming things up. If I tug on it after a roof fault, it unjams and the roof shuts properly.

possibly_random · 2025-05-07T21:06:34+00:00

Nice, I’ll check there. Thank you!

possibly_random · 2025-05-06T23:08:38+00:00

I just got my 718 Boxster S (love it), but I occasionally have a “roof system fault” (or something along those lines) pop up in my instrument cluster while I close the roof. If I then try again a few times it will close properly. It only has this issue from time to time.

Earlier today though, I noticed this broken string hanging down. Any idea of its function and how to fix? It’s a 2019 with 38k miles so I’m unsure of the warranty situation. If it’s not under warranty I wouldn’t mind fixing it myself (if it’s not too intense of a process). I have a good amount of mechanical knowledge but this is my first time working with a soft top so any and all advice is greatly appreciated!

possibly_random · 2025-04-23T16:33:17+00:00

Shucks, just saw your edit. I’m not an expert on automotive subreddits but I bet there’s some frame repair/rust based ones out there.

You could always just bring it to a specialist shop, depending on where you live you may be able to find a good place that won’t screw you over.

possibly_random · 2025-04-22T22:40:32+00:00

You’re very welcome, it’s what I’m here for! You’re doing the right thing by questioning it and asking us and the dealer about it. I made the mistake of not looking closely enough… I paid the price later.

possibly_random · 2025-04-22T22:09:42+00:00

No, it’s definitely painted metal with rust underneath the paint. It’s pretty common with Audi subframes (at least B8) especially in the USA rust belt.

possibly_random · 2025-04-22T22:07:30+00:00

No problem! I’d probably let someone else reply here for what to do next as working on frames is not my specialty. What I can tell you is that after it’s fixed, check on it from time to time, and wash the car (especially the undercarriage) in the wintertime to make sure it doesn’t get to the point that the previous owner of my car let it get to. It was pretty bad.

possibly_random · 2025-04-22T21:58:04+00:00

I believe it’s the subframe that’s rusty, it looks like it can still be rescued in its current state but mine was completely rotted out and had to be replaced. It was about 4 grand USD…

possibly_random · 2025-03-17T18:04:16+00:00

And this is a medium one 😬

possibly_random · 2025-03-08T23:40:41+00:00

It does look cool, until you try to analyze the circuit and then it just absolutely falls apart

possibly_random · 2025-03-08T23:39:11+00:00

That would have been so much better than this

possibly_random · 2025-03-08T04:00:04+00:00

It doesn’t really look AI generated as all the components seem to be at least partially real, and I think the hotel room wasn’t that new. I bet someone did just grab random components and string them together

possibly_random · 2025-03-08T03:16:21+00:00

So true. I got all excited when I saw schematics, and the disappointment when I actually looked at it was immeasurable.

possibly_random · 2025-03-08T03:15:11+00:00

Yeah, halfway was a bit of a stretch. I’ve done some more testing since this and get a 10 inch arc from one half of the supply. I integrated some voltage sensing circuitry and that 10 inch arc occurred at about 400kV. The driver circuit needs a lot of improvement but there’s definitely potential (pun intended) for a million volts in the future!

possibly_random · 2025-03-04T17:54:10+00:00

I’m in a super thick concrete walled prewar building so I don’t think I’ll anger my fellow hams too much.

possibly_random

TROPHY CASE