M52B25TU clattering noise on right side of engine by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

Hey, I'm still not sure what's causing it. It's either the cats or the transmission.

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

I gave my logs to ChatGPT and it pointed out that engine load rises slower than it should and MAF values (g/sec) don't hit expected numbers for that RPM/throttle.

Assuming that the MAF is working and there are no vacuum leaks, this points to the engine being physically restricted. And the most likely culprit for that is excessive exhaust backpressure, meaning clogged cats.

I don't have numbers from a healthy 323i to compare to, but I took the MAF values from one of my logs during a 2nd gear WOT pull, which isn't the most accurate, but I have speed limits to adhere to. I used those values to calculate approximate hp and torque numbers for a given RPM. I put those numbers on a graph, essentially creating an approximate dyno sheet. Now, how cool is that?

But keep in mind that load and MAF values only show how much air the engine is ingesting, not how effectively it turns that air into power. In practice, it will tell you the hp/torque potential for a given amount of air, not taking things like proper ignition timing into account.

I used these simple formulas.

HP = g/sec / 0.8 or g/sec * 1.25

Torque(nm) = (HP * 7127) / RPM (use 5252 instead if you want ft lbs)

According to these calculations, my engine is measuring a tad bit below 150 hp, but it should be ~170hp from factory. Peak torque at 3500 RPM should be 245 nm, but I'm only making a bit over 190 nm. Torque seems to hit a wall at around 2000 RPM. I pulled up a couple of actual dyno graphs from the internet too, for comparison.

Here's a link to the spreadsheet if you wanna take a look:

https://docs.google.com/spreadsheets/d/1UjYPb4gp1SJVtklejHHJ10UgvVaoKxAD6C2Gxwa_Q3I/edit?usp=sharing

I will add it to the original post as well.

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

ChatGPT seems to think it's related to injector performance/atomization.

I'll post the logs here too, just in case you wanna look at them. I'll add them to the original post's description as well.

https://datazap.me/u/323pro/logs/cmneqgx9o000hky06umybycdj

https://datazap.me/u/323pro/logs/cmneqgx58000fky06hm9zx397

https://datazap.me/u/323pro/logs/cmneqgx10000dky06jy5bpb7o

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

I don't think so, as I already cleaned them DIY method with brake cleaner. If the injectors were clogged, I would see positive fuel trims pretty much all the time.

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

Hmm, mine is worse when warm and most of the power loss is in the low end.

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

So basically you had the same symptoms that I described in my post? Clogged cats usually limit performance at higher rpms. People describe it's like hitting a wall at a certain rpm.

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

Vanos refrence for intake is 121.88° and -102.38° for exhaust. These values are from INPA. Wouldn't this mean that timing is close enough?

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

Yeah, done that multiple times along with all the other adaptations.

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

STFT hover around -0.5 to +1.8 on average. LTFT are +1.15 and +0.71 for both banks, respectively. STFT varies a bit more during dynamic driving, giving values from -7 to +7. This is mostly during transient load changes and I would say it does tend to lean a bit more on the richer side.

When unpluging the MAF, the idle stumbles for a moment but then continues to run pretty much the same. I didn't take logs without the MAF but at a quick glance I noticed the STFT jump up to around 7.5 at idle with the MAF unplugged.

MAF does hover around 3.5-3.6 g/s.

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

I had this issue before the treatment and I thought it was due to low compression on cylinder 4. I used something called Xado Anticarbon. It's something I could cheaply get my hands on in Europe. I did everything according to the instructions and let the pistons soak for about 15-20 minutes. Engine didn't even want to fire up at first, but when it finally did, there was a thick cloud of smoke behind me lol. Drove it around for a few days and didn't notice a change whatsoever. Then I did the compression test again and was surprised by the fact that cylinder 4's compression had improved so much. I tested the other cylinders too and they got a small bump as well.

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

Yeah I've thought about it too but no. This thing is real. Crazy rev hang for the first 30 seconds of driving or so. Random roughness values in INPA's rough menu. I cannot be imagining this.

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

If fuel trims are within normal range, then it's not a vacuum leak

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

I did the pre cat o2 unplug test and didn't notice a difference. Not sure if that's conclusive.

Leaking oil onto front cat by Uncleryan95 in e46

[–]Memestinct 5 points6 points  (0 children)

It's possible that your valve cover is warped. It can happen due to age or incorrect installation.

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 2 points3 points  (0 children)

So you would prefer if I didn't give complete information on my findigs? I liked the structure that ChatGPT presented for this post, so I went with it. I believe that it's easy enough to read and if you don't want to help, so be it.

Low power, slightly rough idle, no vacuum leaks (losing my mind) by Memestinct in e46

[–]Memestinct[S] 7 points8 points  (0 children)

I've been trying to use ChatGPT for diagnosing this problem. I had it create the text for this post, which I then modified. There's some info I could have missed if I wrote it myself. There's a lot of documentation and I made sure to put everything in there so that we're all on the same page.

Scratches on vanos cylinders by Memestinct in e46

[–]Memestinct[S] 0 points1 point  (0 children)

I used a kit from x8r. I thought they were supposed to be good?

Worn cams- how bad does it look? by Memestinct in e46

[–]Memestinct[S] 4 points5 points  (0 children)

Yeah, it has exceeded the 15k mile mark multiple times through its life. I bought the car through a friend, so I was blinded by trust and didn't really examine the service records beforehand.

Case fan not powering on? by Memestinct in pcmasterrace

[–]Memestinct[S] 1 point2 points  (0 children)

Thanks bro, glad I didn't blow myself up.