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Discussion Starter · #1 ·
I have got a problem of my 2001 BMW 520i, when i start the engine in the morning, it shakes badly, and i turn it off then turn it back on, the problem is gone.

I took my car to BMW service department, had a check ,been told was the misfire on cylinder 1 and 4.

to make the problem go away, do i just change the coils and spark plugs? and what brand do i use, can you please make some suggestions

Thanks very much for help
 

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I seem to remember I had something a bit like yours, on my 5' and that was an engine sensor..........

Tom
 

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Have you checked the HT leads are in one peice and condition of the plugs, choked etc? You gotta start simple. A coil problem would be easily indicated and they should have told you if this was the problem.

I beleive your cam sensor would give you these sorts of problems. The ECU is giving incorrect fueling responses to valve positions when you first start the car causing it to shake, when you stop it and restart for some reason it correctly picks up the cam shafts position giving correct fueling. Does the car run poorly/sluggish if you try to drive it when it shakes? If you have the time maybe take the cam sensor out and check it for cracks, its a magnetic coil pickup and if cracked will fail intermintently or when cold etc.

If its an M52 engine, the cam sensor is no 17 here (99% sure)

http://www.realoem.com/bmw/showparts.do?model=DM21&mospid=47537&btnr=11_1480&hg=11&fg=15

I am pretty sure your problem is not the plugs and leads though.
 

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Discussion Starter · #8 ·
Have you checked the HT leads are in one peice and condition of the plugs, choked etc? You gotta start simple. A coil problem would be easily indicated and they should have told you if this was the problem.

I beleive your cam sensor would give you these sorts of problems. The ECU is giving incorrect fueling responses to valve positions when you first start the car causing it to shake, when you stop it and restart for some reason it correctly picks up the cam shafts position giving correct fueling. Does the car run poorly/sluggish if you try to drive it when it shakes? If you have the time maybe take the cam sensor out and check it for cracks, its a magnetic coil pickup and if cracked will fail intermintently or when cold etc.

If its an M52 engine, the cam sensor is no 17 here (99% sure)

http://www.realoem.com/bmw/showparts.do?model=DM21&mospid=47537&btnr=11_1480&hg=11&fg=15

I am pretty sure your problem is not the plugs and leads though.

Thanks very much for help, i took the coil out , i can only see some burned marks on the connector, however it doesn't look like it is damaged.is that mean the coil is out? or the problem with the cam sensor?

yes it runs poorly when it shakes, seems like the accelerate respose slowly.
Thanks
 

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I don't think so, I'd still put money on the cam or maybe even the crank given your symptoms. Stupid if you don't check for air leaks first though, although if that was the problem I would expect a air mass meter flow fault code.
 

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Discussion Starter · #11 ·
thanks heaps for the replys. i am not a mechanic, i can only do some simple checks. i will take my car to the garage to check out the cam sensor see if it's alright. By the way if it is broken, how much does it normally cost to replace it. Thanks
 

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I got a new crank sensor of Ebay for £20, cam sensors are more or less the same thing. The only way I confirmed my crank sensor was faulty was to replace it. It was the symptoms that diagnosed it. Get ting the codes read just put me on an endless cycle, although you have to get this done, as you have. Good luck man, hopefully the garage can get straight round to fixing it.

Do you not fancy having a go yourself? If you get a good manual and think everything through before you do it you'll find it is actualy not to hard. Go for it! Take the thing apart!
 

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Discussion Starter · #13 ·
got my car checked yestoday, i have been told there is nothing wrong with the camshaft sensor and crank sensor, so they swap coils around see if it still misfire on cylinder 1 and 4, if so then it is the problem with the engine control unit, otherwise its the coil.
 
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