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Sept 30, 2011 16:50:16 GMT
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well after 10 years of ownership,and just over 300k miles,my BMW e39 523 has failed its first MOT,and it has made a big impression on the atmosphere.
Are we all ready for the results?
Fast idle test
CO=7.470%(limit is 0.300%)
HC=282 ppm(limit 200)
Lambda=0.795(limit 0.970-1.030)
Natural Idle Test.
CO=2.201% (limit 0.500%
Now to be honest it smelt rich,and it has starting using more fuel that normal, so I know the garage isnt trying to pull a fast one.
I do oil services every 5k and a Inspection 1 every 15k, so its well looked after.
Could this just be a lambda fault? or somthing abit more!, the car doesnt smoke rattle or bang,it uses no oil or water .
In short HELP
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Sept 30, 2011 17:01:01 GMT
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Sounds like lambda to me - but could also be MAF or a temperature sensor.
Maybe see if it's throwing up any fault codes?
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bl1300
Posted a lot
Posts: 1,678
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Sept 30, 2011 20:09:26 GMT
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CAT?
Also if you take it for a blast do those figures drop. For some reason engines that just pootle around town at low revs can be improved in this respect by taking them for a good hard thrash
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Current fleet.
1967 DAF 44
1974 VW Beetle 1303s
1975 Triumph Spitfire MkIV
1988 VW LT45 Beavertail
1998 Volvo V70 2.5
1959 Fordson Dexta
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Sept 30, 2011 20:21:48 GMT
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It's running rich (low lambda) hence the high CO (poor combustion) and high HC (unburnt fuel in exhaust)
Check the water and air temperature sensors - somewhere online should tell you what resistance values they should be at X temperature and how to test your specific ones. If they both check out OK I'd, try sticking a universal lambda sensor on (£25 or so) and see how you get on. Lambda sensors aren't easy to test in any meaningful way.
An italian tuneup (thrashing it) will warm the cat up and make it work a bit harder, but it only works for borderline cases, I very much doubt you'll have any joy.
Driving round running as rich as this for a while won't have done the cat any good, though.
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Sept 30, 2011 20:25:29 GMT
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All most certainly lambda, the specs show she's waaaaaay too rich.
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1994 Rover Metro
1994 Peugeot 405 Estate
1991 Rover Metro Gti 16v
2001 Fiat Seicento Sporting
1999 Fiat Punto 1.2
1994 Peugeot 106 Xnd (x3)
1991 Westfield 7
2004 Landrover 110 SW
2003 Seat Ibiza 1.9Tdi Sport
1959 Ford 107e Prefect
1992 Suzuki Vitara
2008 Skoda Fabia
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mk2cossie
Club Retro Rides Member
Posts: 3,060 
Club RR Member Number: 77
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MOT FAILURE---- EMMISsIONSmk2cossie
@mk2cossie
Club Retro Rides Member 77
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Sept 30, 2011 21:09:58 GMT
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never had much luck with universal lambdas at work, and experience has shown that the few extra quid for a direct replacement NTK one is the way to go ;D it may be the MAF though, as the german motors do seem to munch through them  does it run any differently with the MAF disconnected? |
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Sept 30, 2011 21:55:05 GMT
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i wouldnt go replacing anything till you crack out the multimeter and test stuff  most garages will have a copy of autodata that'll give the specs to check throuhg the management system |
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Sept 30, 2011 22:56:58 GMT
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You can test a lambda sensor in a very meaningfull way using an oscilloscope. Pre cat they should switch from rich to lean at about 1hz. After the cat, provided its doing its job, they should stay lean. If they both switch at the same rate your cat is goosed. Admittedly not everyone has a scope to hand but most eobd scan tools should give you the same data.
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R.S. Autotech. Servicing/Repairs/Diagnostics.
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Sept 30, 2011 22:59:46 GMT
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Also its worth noting that if the cat is ok it won't be for much longer after all that fuel has gone through it.
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R.S. Autotech. Servicing/Repairs/Diagnostics.
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Right,had it on carsoft this morning,and low and behold it came back with lambda sensor bank 1-3, and 4-6 after cat............however my sensors are before the Cat so I'm hoping this is just a simple error.
Can the Lambda sensors being fooked really cause such high readings? either way I'm off to by two replacments
With regards the cat,this is a point i take on board,the exhuast system including the cat is oringal so well past its sell by date,however last year it whilstled throuhg the emmision test without a issue.
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ChasR
RR Helper
motivation
Posts: 10,307
Club RR Member Number: 170
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MOT FAILURE---- EMMISsIONSChasR
@chasr
Club Retro Rides Member 170
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Regarding the Lambda, yes, it can cause your car to drink like George Best. No other errors came up? (on the Fords, the Lambda errors tie in with vacuum leaks).
Another point, if it is the cat, try and get a good secondhand Genuine BMW cat. Yes it may cost almost as much as a pattern cat but it can potentially save you LOTS of hassle (two cars I have had with pattern cats have been a pain: First car (a 306) on an 8 month old cat I could not thrash hard enough to get below MOT specs (passed on a PSA cat (a lucky find)), second car (the 106) barely passed its last MOT on emmisions (with the PO) and failed badly this time (I may have fitted a decat after this...).
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Look at what the fault code is telling you. Both sensors downstream of the cats have failed yes? Or could it be that the cats have failed and are causing the ecu to 'see' an error with the sensors. Remember the lambda sensor is used to gauge the health of the cat so if the sensor is working then the fault most likely lays in the cat. A faulty downstream sensor won't cause you to run rich.
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R.S. Autotech. Servicing/Repairs/Diagnostics.
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Rev,the lambda sensors are on the manifolds,thereS about 1.5ft of down piper before the car,
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Up there you said they were after cat. Most vehicles have pre and post cat lambda sensors. It's important to know what ones are bringing up a fault before you can start diagnosing it.
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R.S. Autotech. Servicing/Repairs/Diagnostics.
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Right just read your post properly. Have a look under the vehicle and you should find another pair of sensors after the cat. If not then you should just ignore any sensor2 faults. Does carsoft give you live data?
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R.S. Autotech. Servicing/Repairs/Diagnostics.
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