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      11-08-2012, 05:54 PM   #6
Three_thirty_I
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Drives: '05 E90 330i Manual
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Finally, some replies, thanks!

Have replied individually below, but some short background:

Car came off motorplan end of June, but have been experiencing this noise noticeably since the beginning of this year (mostly when driving in a more relaxed manner in the lower revs). Been searching and reading up, posting here and other forums since then. Various thoughts from rattling dual mass flywheel to pinging and then possible DISA flap rattle on one or both of the DISA flaps. The car went into the agents in May while still under motorplan to get this sorted out as well as do a general nose to tail inspection on the car to ensure that everything was spot on. The concluded that the engine was pinging and updated software resetting adaptations etc. No improvement and then eventually motorplan ran out with them insisting that it is normal with out fuel (95 octane unleaded) and that other BMW's suffer from this to an even worse extent (BS baffles brains).

BTW, the car only has 67k km on the clock at present, so pretty low mileage, but is not driven for short trips where the engine does not get up to proper operating temperatures - I am very fussy about things like that, plus I never idle the engine warm from cold which is just a petrol wasting premature engine wear and tear treatment. Rather immediately drive off gently until I can get an oil level reading which takes longer than my Wife's E46 320i to show normal temperature range for instance.

DIY changed spark plugs (fitted Bosch for a change since the OEM plugs were NGK) even though the old plugs still had 35k km left on them but 7 years old. No improvement so ran a tank with Liqui Moly Injector Cleaner, also no improvement. Took the car to a local specialist tuner and let them spend a day with the car. Their live diagnostics found a few issues, or at least they interpreted these issues I gather - no codes founds, but rather a case of looking at values. Thermostat is not properly regulating engine temperature in as far as it is often preventing the engine from reaching proper operating temperature on typical cold Winter days (not a problem right now being Summer almost). They claim that the noise is from the DISA flaps making constant adjustments and/or fluttering. Engine is NOT pinging and the knock sensors are working fine. Valvetronic motor is out of spec by 10% but can be recalibrated via software.

Agents had the car again with this info to run their own tests again, but you guessed it, all is fine because apparently no error codes come up. Eventually they did see some of the issues with the thermostat, but weren't willing to change anything. I gather that they think that the M54 and N52 DISA flaps have identical symptoms while the former is vacuum pipe actuated and the latter motorised and controlled by the DME.

With this video posted above, this is the first time that I am able to get the DISA flaps to make a noise that closely resembles the type of noise that I am hearing, albeit it is a lot louder to be then heard above the sound of the engine and is a rattle rather than just those single rattly clicks. The question posed is to find out if this noise is normal for a properly normal functioning DISA flap or confirmation that this specialist tuner has hit the nail on the head with their assessment.

I am not keen to take a chance and simply replace these costly items in the hopes (gamble) that it will solve the problem - RealOEM to get an idea of the prices for no 1 and 2 DISA motors, a thermostat and associated bolts and gaskets, coolant etc. Then there is still the question about the Valvetronic motor, costs about the same as one of the DISA motors and then for that matter the eccentric shaft sensor for the Valvetronic. Oh, and this past weekend I cleaned both Vanos solenoids just for good measure - exhaust solenoid dirtier than the intake solenoid.

So there you have it, tearing my hair out trying to solve and annoying set of issues that BMW motorplan through the dealer network was suppose to be able to fix! Check this thread out of interest: DISA Question

Quote:
Originally Posted by leebermeister View Post
Does your rattle noise occur between 2 - 3,000 rpm under moderate to heavy acceleration?
Yes, from almost pull off speeds actually, but pretty prominent between 1800 - 3000 rpm, sometimes a bit higher on gear change. But basically usually within it's lower rev range. Mostly moderate acceleration.

Quote:
Originally Posted by Phil325i View Post
"...a rattling noise while driving..." is a bit vague. You'll need to give us some more info if you want suggestions. Speed related? Rotational? Engine speed related?
To be honest, just searching my thread you will find plenty dealing with this over the course of 7 - 8 months. At first I thought it was the dual mass flywheel that was chattering, then the agents said it was pinging. Changed spark plugs and ran Liqui Moly Injector Cleaner in a tank of fuel. But all with no change or improvement. Found a few threads through google searches pertaining to DISA rattling noises on N52 engines.

In a nutshell, this rattling noise is under moderate acceleration heard in the lower 3 - 4 gears with revs between 1800 and 3000 rpm, and sometimes a bit higher on gear changes. This noise is only heard when the engine is under load - never heard it while revving the engine or under off throttle conditions.

Other semi-DISA flap related issue is an intermittent dip in power during acceleration between 3000 and 4500 rpm.

Quote:
Originally Posted by jc5988 View Post
u can hear that noise when you drive?
Noise only when driving, never when the car is stationary (not like the metallic hydraulic lifter ticking sound - mine is luckily not affected by that).
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Last edited by Three_thirty_I; 11-08-2012 at 06:38 PM.
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