Hard pooping or knocking

Z4project

Member
2003 BMW Z4 3.0i 100,000
I’ve change my headers to stainless about 3 years ago but not till about a year after I Started to hear a hard pop or knocking sound coming from the top of my engine I can’t turn on my car at all it doesn’t stay idling. I would say it’s coming from the passenger side of the motor , a mechanic said it was my thermostat so I change it and also I replaced spark plugs and ignition coils and oil change . also a other couple a/c sensor and oil sensor but the noise is still there. What can it be any helps will be grateful thanks 🙏🏼. Will be putting it on the computer again to see if any other more code may have pop up.
 
Can you put a video on youtube so that the noise can be heard?

As you have fitted SS headers did this also include fitting new catalysts?
 
Davz said:
Can you put a video on youtube so that the noise can be heard?

As you have fitted SS headers did this also include fitting new catalysts?
Davz said:
Can you put a video on youtube so that the noise can be heard?

As you have fitted SS headers did this also include fitting new catalysts?
Davz said:
Can you put a video on youtube so that the noise can be heard?

As you have fitted SS headers did this also include fitting new catalysts?

Yes I’ll post it and I have stainless steal headers they were plug and play
 
Davz said:
Can you put a video on youtube so that the noise can be heard?

As you have fitted SS headers did this also include fitting new catalysts?


I put it on you tube


https://youtu.be/_9vhIK4tQTA
 
You said it started about a year after you changed the headers 3 years ago, does that mean it’s been making this noise for 2 years?
Have you been driving it all that time?
Has it been getting worse over the 2 years?
 
You say headers so I assume you're American? Meaning your passenger side is the exhaust side of the engine, given the manifold change I'd check all the studs are tight and that there are no cracks in the manifold, I'd imagine that the poor idle could be caused by air getting into the exhaust before the lambda sensors giving a false reading, check they are tight as well.

Does it only happen as the engine is warming up or does it keep making the noise once it's up to temperature?
 
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