Hi There
Question that someone can hopefully help with.
My 318is '98 failed NCT last week for high CO at high idle

Results were 0.53% (I think - will update later - I don't have sheet in front of me now) at 2850 rpm
CO and low idle and lambda were all in spec. HC's for both were also in spec.


So I'm suspecting air leak somehwere, or lambda faulty or cat gone. Started by pulling codes - got the following

RESULT: 4 errors in error memory !-------------------------------------------------------------
10 Lambdasonde vor KAT OBDII Fehler !!
Error frequency : 255 Logistic counter: 40
Motordrehzahl 2080.00 1/min Motortemperatur 94.50 Grad C Sondenspannung vor KAT 0.32 V aufgetreten vor (rel. BZ) 146.00 h
Signal fehlerhaft Abgasrelevanter Fehler (nach Entprellung MIL Ein) Fehler momentan nicht vorhanden sporadischer Fehler
Errorcode: 0A 94 D4 10 00 41 FF 28 34 BE 79 72 07 34 C1 75 74 07 43 BF 68 76 07 1D BE 77 25 0D-------------------------------------------------------------
62 Aussetzererkennung Summenfehler OBDII Fehler !!
Error frequency : 35 Logistic counter: 28
Motordrehzahl 1560.00 1/min Lastsignal 1.25 ms Motortemperatur 66.75 Grad C aufgetreten vor (rel. BZ) 103.80 h
Maximalwert ueberschritten Abgasrelevanter Fehler (nach Entprellung MIL Ein) Fehler momentan nicht vorhanden sporadischer Fehler
Errorcode: 3E 91 91 82 00 83 23 1C 27 19 99 18 09 3D 6D B2 5D 09 58 68 5F 63 09 17 2F 5D DA 0C-------------------------------------------------------------
52 Aussetzererkennung Zylinder 3 OBDII-Fehler !!
Error frequency : 21 Logistic counter: 21
Motordrehzahl 1560.00 1/min Lastsignal 1.25 ms Motortemperatur 66.75 Grad C aufgetreten vor (rel. BZ) 103.80 h
Maximalwert ueberschritten Abgasrelevanter Fehler (nach Entprellung MIL Ein) Fehler momentan nicht vorhanden sporadischer Fehler
Errorcode: 34 91 91 82 00 83 15 15 27 19 99 18 09 3D 6D B2 5D 09 2E 47 BD CD 09 14 1A BF B1 0C-------------------------------------------------------------

53 Aussetzererkennung Zylinder 4 OBDII-Fehler !!
Error frequency : 10 Logistic counter: 28
Motordrehzahl 1160.00 1/min Lastsignal 1.75 ms Motortemperatur 30.75 Grad C aufgetreten vor (rel. BZ) 56.90 h
Maximalwert ueberschritten Abgasrelevanter Fehler (nach Entprellung MIL Ein) Fehler momentan nicht vorhanden sporadischer Fehler
Errorcode: 35 91 91 82 00 83 0A 1C 1D 23 69 ED 0A 30 69 61 F9 0A 23 1E 5D 5F 0B 17 2F 5D DA 0C ==================================================

Lambda being thown up here but is it going out of range due to an air leak or is it actually faulty.

I had a look at the lambda voltage then - see you tube video below. Could anyone familiar with looking at this comment - it seems to be reacting a bit slow to me (but I haven't looked at live data like this before - ideally I know an oscilloscope would be better) and sometimes seems to stop and a midpoint voltage rather than swing from high to low.

https://www.youtube.com/watch?v=fGPEOgql3r8



I do also feel a slight surging when driving and can see the mpg guage move in time with this surging - posted about this last year here http://www.bmw-driver.net/forum/showthread.php?t=80617 (after which it did pass NCT last year following cam sensor replacement)