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BMW 540 1998 - Running rough, multiple misfires - Fixed #

Posted by Mark Duhigg on April 3, 2009, 4:29 pm

Year of Manufacture *: 1998
Engine Code or Type *: 448S1
( Optional ) Scanner used: KTS

It seem I am getting them all this week!!!
This BMW is running rough when drive is engaged runs o.k on road just lumpy idle worst when cold.
Only fault codes multiple misfire cly 1,2 and 3. Replace plugs and swap coils But fault code still on 1,2 & 3 clys. Has what looks to be an aftermarket cat on said bank and was thinking that cat could be blocked.
Would this flag a misfire and how do I check for back pressure from the cat????
This one is doing my head in checked all the obvious like injectors air leaks etc etc..
MARK

Re: BMW 540 Multiple Misfire

Posted by Tom Fitter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5519' width='330' height='300' border=0 style='border:none;'> on April 3, 2009, 5:51 pm, in reply to "BMW 540 Multiple Misfire"
Tom Fitter

I think I would double check for air leaks.

Re: BMW 540 Multiple Misfire

Posted by martin young <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2736' width='330' height='300' border=0 style='border:none;'> on April 3, 2009, 6:27 pm, in reply to "BMW 540 Multiple Misfire"
Martin Young

have you checked the maf sensor?
martin

Re: BMW 540 Multiple Misfire

Posted by ROY RITCHIE <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5115' width='330' height='300' border=0 style='border:none;'> on April 16, 2009, 11:32 pm, in reply to "Re: BMW 540 Multiple Misfire"

1 2 3 cylinders are on same bank,Check to see if one cat is blocked.

Re: BMW 540 1998 - Running rough, multiple misfires #

Posted by Joe McGeoghan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5290' width='330' height='300' border=0 style='border:none;'> on April 17, 2009, 4:40 pm, in reply to "BMW 540 1998 - Running rough, multiple misfires #"
Joe McGeoghan

Last one I had with same fault was blocked cat.

Fixed #

Posted by Mark Duhigg on May 2, 2009, 6:25 am, in reply to "Re: BMW 540 1998 - Running rough, multiple misfires #"
Message modified by board administrator May 5, 2009, 3:12 pm

Finally fixed this.
After smashing it into a ramp post sorting it out.OOPS
Turn out to be oil breather at back of manifold.
Cheers for all you input.
Mark

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