Detonation / knock?

[Shrm4n]

Hello,

Apologies in advance if this is posted in the wrong section.


I've been dealing with what appears to be a detonation or knock issue. I'm experiencing a loss of power, acceleration, and increased induction noise. I've also noticed odd behavior from the DCT, as it seems to rush into 7th gear as quickly as possible in any auto shift setting, causing the car to perform poorly when driving around town. Initially, I thought to service the DCT first, but all transmission symptoms cease when the car is running well. There are no diagnostic codes, and the car is completely stock.

On the rare occasions it runs well, I can immediately tell by how little throttle input is needed just to get out of my driveway.

After consulting threads with similar symptoms, I've replaced the spark plugs, fuel breather valve, primary O2 sensors, fuel injectors, and the low-pressure fuel sensor behind the plenum. Unfortunately, none of these fixes have resulted in a long-term improvement. Most recently, the car seemed to run well for about 100 miles after replacing the fuel sensor, but then it returned to its sluggish state. I've tried fuel from multiple stations and brands to rule out the possibility of bad gas. It's worth mentioning that I live in California, where only 91 octane is available.

I'm reluctant to start another thread on a somewhat known issue, but I haven't seen many of these cases fully resolved. I don't consider myself someone who gives up easily, but this issue is beginning to frustrate me to the point of considering selling the car. I have a BW forward X pipe and Epic tune waiting to be installed, but I really want to resolve this issue before adding any modifications.

Any suggestions or insights are greatly appreciated. I've exhausted all related threads and am finally reaching out for help!

[Redd]

Error codes will help.

[Shrm4n]

Originally Posted by Redd

Error codes will help.

No codes so far.

[Redd]

Have you checked your ground straps?

I would also drive without the plenum just to eliminate possible intake air leaks.

[spammysammich]

Smoke test your car.

[bgexpress]

Battery replaced?

[Shrm4n]

Originally Posted by bgexpress

Battery replaced?

Haven’t replaced it, but tested at 12.7v resting and 14v while running.

[amrazM]

did you do a leakdown test or a compression test to rule out a broken valve spring?

[Shrm4n]

Originally Posted by amrazM

did you do a leakdown test or a compression test to rule out a broken valve spring?

This is next on my list. Currently calling around in the socal area trying to set something up.

[BimmerMan33]

Could this be fuel pump related?
If there is a misfire due to any reason, ECU should throw a code..