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MINI Cooper R56 1.6 2008 - Poor idle - Fixed #

Posted by Gerard O'Leary on June 30, 2015, 7:47 am

Year of Manufacture *: 2008
Engine Size and Code *: 1.6 N12

Hi

MINI Cooper R56 has poor idle after short drive, cyl 2 shows misfire even though gives correct scope readings, have changed chain / tensioner, vanos unit inlet side, cam sensors, crank sensor, complete fuel rail and injectors, temp sensor

Checked oil pressure, changed vanos actuators, re checked valve timing, checked fuel pressure, changed coils and plugs, smoke test showing no leaks.

Confusing thing is if idling and misfiring when any of cam sensors is disconnected the misfire instantly disappears and won't return until switch off and restart.

No misfire from cold and just like clockwork misfire appears when hot

Any help would be appreciated

Gerard

Update

Posted by Gerard O'Leary on June 30, 2015, 2:15 pm, in reply to "MINI Cooper R56 petrol "
Edited by board administrator July 1, 2015, 12:31 pm

UPdate

Just did full software update --- no change , misfire starts after 17 mins idling and when temp reaches 96 degrees , pull off any of the two can sensors and car returns to smooth idle until switch off and restart

Any ideas?

Gerard

Re: MINI Cooper R56 petrol

Posted by Fiachra Purcell <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3006' width='330' height='300' border=0 style='border:none;'> on June 30, 2015, 2:26 pm, in reply to "MINI Cooper R56 petrol "
Fiachra Purcell

Post the waveforms so we can look at them.
If you have a WPS I would do running compressions.
Regards

Update

Posted by Gerard O'Leary on June 30, 2015, 5:41 pm, in reply to "Re: MINI Cooper R56 petrol "
Edited by board administrator July 1, 2015, 12:32 pm

Update

Removed cyl head to check for sticking valve, found a loose valve seat, head off to machine shop for sorting , update when it returns and refitted

Thanks for the help guys

Gerard

MINI cooper R56

Posted by Gerard O'Leary <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3412' width='330' height='300' border=0 style='border:none;'> on July 2, 2015, 5:18 pm, in reply to "Update "

Latest update ,head back on and everything fine until it gets HOT and problem is still there , misfire on no 2 cylinder , again remove any cam sensor when misfiring and problem solved until restart and temp reached . have changed the following cam sensors , vanos units , vanos actuators, 'knock' sensor , temp sensor . oil pressure is good and also stable 30 psi at idle ( range should be 10 to 30 ) while head off we double checked valve gear including concentric shaft and all tappets for damage etc everything fine . compression good on all cyls and no issue on leakdown test ,checked cat for blockage again everything ok , next we feel is perhaps engine loom even though all looks well and all ecu pins are good with no signs of damage or corrosion ,
any ideas ?
G

Re: MINI cooper R56

Posted by mark mcgrath <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2806' width='330' height='300' border=0 style='border:none;'> on July 2, 2015, 7:48 pm, in reply to "MINI cooper R56"
Mark McGrath

check wiring harness from injectors down main harness
we had one that harness was faulty
you could replicate the fault sometimes
by just pressing down on the loom

Re: MINI cooper R56

Posted by tony bickers <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5143' width='330' height='300' border=0 style='border:none;'> on July 2, 2015, 11:18 pm, in reply to "Re: MINI cooper R56"

What a nightmare !

Re: MINI Cooper R56 petrol

Posted by andy pethig <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3731' width='330' height='300' border=0 style='border:none;'> on July 3, 2015, 9:49 pm, in reply to "MINI Cooper R56 petrol "

what are exhaust gas readings when its misfiring ?

and long and short term fuel trim ?

Re: MINI Cooper R56 petrol

Latest , problem solved , after lots of testing and replacements of various sensors , modules etc including ECU we decided to go back to basics despite leakdown and compression tests being ok we removed the head again and swapped with a complete used head . ran for over an hour and no issue ---problem solved , quick removal of the exhaust valves from the original head revealed a problem with valve seats, looks like a different angle was cut on the seats to the valves when we sent the head out for refurb / repair and it had just enough of a seal at cold idle to work and then failed when hot .we had no reason to doubt the work as it is always good , will be doing a full post mortem tomorrow on the head .thanks for the replies guys and

Re: MINI Cooper R56 petrol

Posted by tony bickers <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5143' width='330' height='300' border=0 style='border:none;'> on July 5, 2015, 9:54 pm, in reply to "Re: MINI Cooper R56 petrol "

I am intrigued, how did you spot valve seat angle wrong ??

Fixed #

Posted by Gerard O'Leary on July 6, 2015, 8:27 am, in reply to "Re: MINI Cooper R56 petrol "
Edited by board administrator July 9, 2015, 7:30 am

It really was go back to basics . We had tried to resolve the problem based on a series of tests based on the information we could get and with no stored codes and all live data looking ok we were pretty sure it was 'mechanical' rather than any software or electrical issue , when the problem was still evident following ECU change we decided to just go back to basics and look at the sequence of events that unfolded from the start .We had a misfire and on compression test we found a valve problem on cyl 1 , head off and sent out to engine shop for repair and all seats cut and valves refaced , head refitted and then the problem appeared after test run , replicated after 17 mins of idle , anyway following lots of replacement sensors etc problem still existed and this led us to firstly check all the valve train for damage including all rockers and vanos units concentric shaft etc etc all with no resolution to the issue , decision made to just swap out the complete head and hey-presto problem solved . a quick check on cyl 2 exhaust valves show a very tiny area where we had 'seal' just enough to cause no problem when cold and major problems when hot btw compression tests were all pretty equal and around 170 psi . we will do a more comprehensive post mortem on the head when we get some time . but I think it was a case of assuming everything was ok with the repaired head and getting bogged down on possible engine management issues when we should have ruled out the basics first .
G

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