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2005 E46 325ci
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318 Posts
Discussion Starter #1 (Edited)
Hey guys if anyone could possibly point me in the right direction it would be much appreciated.
I've got a 2005 E46 325ci (217k km's) and I've had this intermittent rattle under load (never at idle) between 2-4k rpm's under heavy load for about 20k km's now and I've replaced my clutch and flywheel, vanos seals (seals and anti-rattle kit), checked disa (minimal play since its only about 2 years old) and checked even exhaust flanges, all heatshields including one on headers.
It sounds like a metallic clanging that almost like hitting a metal pole with stick repeatedly when accelerating
PS.
No codes (pending or confirmed) and fuel trims under load are 1-2 but at idle 8-10 (not sure if relevant but just putting it out there)

I've suggestions that have been anything from head gasket failure (never have overheated and not losing coolant at all), to knock sensors (not sure how that would come into play) to even carbon deposits raising my compression (I keep my engine as clean as I can, only the best oil, 5w40 liquimoly every 8k km's and only the very best gasoline I can get my hands on in Canada, Shell 91 or Chevron 94) but still no definitive answer that truly fits all my symptoms.

Any help would be greatly appreciated.

It's hard to catch the sound on camera since its only present under load between 2-4k rpm's but this video has an almost identical sound to mine, granted the sound in this video is much louder than mine but it's the closest example I could find




What could I be overlooking?
 

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2005 E46 325ci
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318 Posts
Discussion Starter #2
Bump

So I have noticed a new loud rattle from the engine bay one evening after a long drive and after listening around I decided to re-check the DISA so I disconnected it and voila the rattling disappeared.
I haven't gone on a drive with the DISA disconnected to confirm whether the original rattle I heard during acceleration was still there but I did order a new unit from FCP and when it gets here ill install it and then go for a drive to see if the original rattle is still there or if it was just the DISA all along.
(Current DISA is 2 years old so I am a bit surprised it need to be replaced already but I do drive quite a bit)

On a side note: Are we able to drive with the DISA disconnected or would that pose more of a threat for the pin to fall out?
 

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the people’s mod
2004 330Ci 115k miles
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15,067 Posts
If the DISA diaphragm tests good, consider just rebuilding it with the G.A.S kit.
 

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2005 E46 325ci
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318 Posts
Discussion Starter #6
If the DISA diaphragm tests good, consider just rebuilding it with the G.A.S kit.
After testing the DISA everything seemed fine and now it's rattling pretty loudly so I'm not sure if the diaphragm would be still holding up or also failing so thats why I decided it would be safer to just replace it with an OEM one from FCP since it was only like $280 USD and that lifetime warranty does come in handy lol
 

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Hey guys if anyone could possibly point me in the right direction it would be much appreciated.
I've got a 2005 E46 325ci (217k km's) and I've had this intermittent rattle under load (never at idle) between 2-4k rpm's under heavy load for about 20k km's now and I've replaced my clutch and flywheel, vanos seals (seals and anti-rattle kit), checked disa (minimal play since its only about 2 years old) and checked even exhaust flanges, all heatshields including one on headers.
It sounds like a metallic clanging that almost like hitting a metal pole with stick repeatedly when accelerating
PS.
No codes (pending or confirmed) and fuel trims under load are 1-2 but at idle 8-10 (not sure if relevant but just putting it out there)

I've suggestions that have been anything from head gasket failure (never have overheated and not losing coolant at all), to knock sensors (not sure how that would come into play) to even carbon deposits raising my compression (I keep my engine as clean as I can, only the best oil, 5w40 liquimoly every 8k km's and only the very best gasoline I can get my hands on in Canada, Shell 91 or Chevron 94) but still no definitive answer that truly fits all my symptoms.

Any help would be greatly appreciated.

It's hard to catch the sound on camera since its only present under load between 2-4k rpm's but this video has an almost identical sound to mine, granted the sound in this video is much louder than mine but it's the closest example I could find




What could I be overlooking?
Drive shaft guibo cracked? The rubber doughnut between the drive shaft and the gearbox output shaft.
 

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2005 E46 325ci
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318 Posts
Discussion Starter #9
Step #3 in this PDF describes how to test the diaphragm.
The rebuild results in a much more robust DISA than a brand new one, and is cheaper.
Just something to keep in mind.
Yep just as I thought, mine shot open when I tested it so I'm guessing its not holding the best vacuum. Good thing I got the new one just in so I should be able to install it in the next few days.
Thanks for the suggestion, once I have more time I think I'll take out the new one after I install it and I'll just upgrade the new one before it wears out.
 

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2005 E46 325ci
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318 Posts
Discussion Starter #10

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2005 E46 325ci
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318 Posts
Discussion Starter #11
Also, as a recent addition, I've been watching my fuel trims and I'm not sure whether the current DISA that I have installed that is wearing out is messing with fuel trims or its related to something else but I drove through the city and then did some highway driving and my fuel trims are absolutely all over the place.
At speed they seem to be lower 1-3 but at idle they will bounce between 8-14.
Then when I start moving they shoot to (-7) - (-10) and then try to equalize.
 

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the people’s mod
2004 330Ci 115k miles
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15,067 Posts
For OBD Fusion logs, driving around is tough to nail down behavior, because everything is constantly changing.
It’s much better to do the three simple types to keep other variables constant.
  1. 5-minute cold start idle
  2. 2-minute 60-MPH highway cruise (use cruise control on a flat freeway)
  3. 2-minute hot idle
Also, a Diagnostic Report at hot idle is very insightful.

Can you get those and post links here?
 

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2005 E46 325ci
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318 Posts
Discussion Starter #14
Cold start: CSVLog_20201019_154122.csv

Highway cruise at 60 mph: CSVLog_20201019_180016.csv

Hot idle: CSVLog_20201019_181424.csv

Also that same day while driving in the city I took off from a set of lights and after I set off and reached around 2.5k rpm's I felt a strong power cut (power completely cut out for a split second) and then power came back and I continued accelerating.
I've had this happen before and I can never pin point when it happens or why since it does not happen everytime I take off from a set of lights.
I definitely think its related to my issue as I think I did hear that rattle when the power cut.
 

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2000 E46 323i, 3.0L and 2.0L Z3's
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817 Posts
Wow, what an improvement. Fuel trims within +/-5%. I would say that you have been successful.

Don't know about your power cut problem. It's around 2,500 rpm that the Idle control valve is taken over by the throttle body as the main component managing the rev's.
 

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2005 E46 325ci
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318 Posts
Discussion Starter #16
Wow, what an improvement. Fuel trims within +/-5%. I would say that you have been successful.

Don't know about your power cut problem. It's around 2,500 rpm that the Idle control valve is taken over by the throttle body as the main component managing the rev's.
Yeah the fuel trims were a bit more consistent although I haven't had the time to actually replace the DISA yet. I will try to get it done within this week and then following that I'll try cleaning the icv but yeah I can only describe it as a strong hiccup like sudden fuel delivery interruption like when my fuel pump failed but I already did replace the fuel pump ( 2 years ago) and fuel filter ( 1 year ago).
These hiccups happen once every few weeks I would say and this has been happening for months now. No codes at all.
 

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2005 E46 325ci
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318 Posts
Discussion Starter #17
Update: Just replaced the DISA today and no difference, the original sound is still there and so is the power hiccup under heavy acceleration and load.
 

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2005 E46 325ci
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Discussion Starter #18
So I will be getting a compression test, leak down test, checking the maf, checking all the plugs and coils, is there anything else I should look at to help my search?
 

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2005 E46 325ci
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318 Posts
Discussion Starter #19
Well as a continued update for those checking in on my progress, I got a leak down test done as well as a compression test and the results are "92 - 95 psi throughout all 6 cylinders for the leak down which is like a new engine" so from my interpretation they're saying at 92-95 psi I'm getting only 10% leakage and for the compression test "210 - 215 throughout all 6 cylinders".
 
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