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2001 540i w/misfire & sensor problem.

2K views 1 reply 2 participants last post by  Penngwyne 
#1 ·
Hello everyone....
I'm having a really huge problem with my Bimmer (2001 540i V8 4.4L).
About 2 months ago, I bought this nice car and it was running great.
Suddenly one morning on my way to work it start idling and having difficult to keep running specially when I was on a red light. If I had the chance to start running and had the speed up to 30 mph, the car was ok.
I took the car to a friend who has a code reader and some experience with cars and the codes where:
201 Knock sensor 1
??? Misfire on several cylinders
??? Misfire on cylinder 1
??? Misfire on cylinder 2
??? Misfire on cylinder 3
??? Misfire on cylinder 4

(Sorry about the other codes... don't remember)

We change the knock sensor and still kept idling on low rpm. But when he erase the code from the ECU reader the rpm went to the roof.
After expending the whole day trying to find the problem and trying all the posibilities in our hands, the problem still continue.

Some of the things we did:
- Replaced the sparks plugs from one side to the other
- Replaced the coils from one side to the other and from another bimmer
- Replaced the knock sensor back to the original

At the end, we poured a little brake fluid on the cylinders 1-4 (for around 10 minutes) to try to clean the valves... and nothing.
Also we measure the compression on the cylinders and they were very low.

Does any of you have an idea of how to solve this problem.
I will really appreciate it before expending a lot of money on repairs.

Thanks in advance
PD: If you need additional info,let me know.
 
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#2 ·
Knock sensor will probably because of misfire
What were the other codes telling you?
If you have a misfire it may be a crank (or camshaft?) position sensor?
May be something to do with spark distribution?
(I don't know much about the v8's though so I don't know what they have)
Are you suddenly using coolant??
Any smoke out of the exhaust?
 
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