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BMW 118i N43B2OUO 2008 - Rough running / cutting out - Fixed #

Posted by John Hall on February 10, 2016, 9:07 pm

Year of Manufacture *: 2008
Engine Size and Code *: 1995 / N43B2OUO
( Optional ) Scanner Used: Delphi DS150
( Optional) Fault Codes: 29DC Cylinder injectors cut out

I have the above with god running but after warm up and idling it logs the above fault and runs rough with very poor acceleration.

When you examine the live data in the fuel pump module it shows desired fuel pump rpm as around 6500 but actual as 3000rpm. I have noticed on other similar cars these are matched ?

When looking in live data for engine control low pressure fuel is around 5.5 Bar but high pressure is 6.0 Bar.

Am i correct in assuming the high pressure is too low and this is causing the issue ??

What should the high fuel pressure be on these at idle as I cannot seem to find an data anywhere ?

Searched this forum and found the "tech note" about high pressure pumps and this covers my model but not engine !

Any help would be appreciated

Re: BMW 118i. Rough running / cutting out

Posted by Ed Kaps <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5536' width='330' height='300' border=0 style='border:none;'> on February 11, 2016, 10:12 am, in reply to "BMW 118i. Rough running / cutting out"
Edward Kaps

Hi John
5 bar supply pressure
100 bar+ system pressure.
Car will run with the 5bar supply pressure (after a fashion) if the HP pump is kaput,not unknown and not cheap.

Re: BMW 118i. Rough running / cutting out

Posted by Andrew Pethig on February 12, 2016, 10:59 pm, in reply to "BMW 118i. Rough running / cutting out"
Edited by board administrator February 26, 2016, 7:54 am

ed has it,

For what its worth i have found on most high pressure systems petrol or diesel you want to see about 1.2 volts at idle for petrols and cranking/ idling for diesels on the rail pressure sensor.

this indicates the correct pressure, if you don't know what the specs should be.

Re: BMW 118i. Rough running / cutting out

Posted by Ed Kaps <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5536' width='330' height='300' border=0 style='border:none;'> on March 7, 2016, 11:02 am, in reply to "Re: BMW 118i. Rough running / cutting out"
Edward Kaps

And, what fixed it then?.

Fixed #

Posted by John Hall on November 24, 2016, 6:10 pm, in reply to "Re: BMW 118i. Rough running / cutting out"
Edited by board administrator November 25, 2016, 11:25 am

Replaced high pressure fuel pump and all ok.

Sorry forgot to reply earlier so i've forgot pressure readings with new pump but considerably higher than these taken during diagnosis.

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