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Vectra 1.8 - MOT lambda value

Discussion in 'Car Repairs / Maintenance' started by Shed Steve, 29 Jul 2012.

  1. Shed Steve

    Shed Steve

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    At it's last MOT at 160,000m, the lambda reading for my 1999 1.8 Vectra, was 1.029, that is just OK, top limit is 1.030. The year before it was 0.997. From this, I reckon that the next MOT in 4 months may be a failure on this. Are these difficult to replace, and is the reading a sign of something else going wrong? I know little about these. The reason I ask, is that the clutch now needs replacing, about £500, and I am wondering if it's worthwhile. I should add, the car has been reliable the past 9 years, no other obvious faults, drives well, and gives good mpg. However, I do have a slight feeling I could be wasting money, and may be better to scrap it. Any advice would be much appreciated, thank you.
     
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  3. Burnerman

    Burnerman

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    The lambda sensor screws into the exhaust pipe, somewhere between the exhaust manifold and the catalytic converter.
    Theoretically they should come out ok, but more likely its cut the wires off time and use a hexagon socket to shift it.
    However.....try a bottle of Forte fuel system cleaner, and submit the car for its test when the cat is really stinking hot...it could well go through.
    John :)
     
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  4. Shed Steve

    Shed Steve

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    Burnerman, thankyou for rapid reply! I think what is concerning me, was the increase in the reading over one year, from 0.997 to 1.029. Seems a lot. Ideally, I would like to test it before decision on clutch, but it is so worn it is not good to drive it now. Could the Cat. be on the way out do you think? Thank you.
     
  5. Karis

    Karis

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    How do you use the car? Slow speed urban driving is not good for MOT test results? I suspect your 1.8 Vectra is petrol so not sure if this is relevant but I had a 2.5 Brava diesel truck which I used as a poodle about in & it constantly failed emissions tests.

    The tester always said “off you go then”; I took it to the nearest duel carriageway & drove it both ways (probably a mile each way) flat out in 3dr gear, it always passed on retest!
     
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  7. Shed Steve

    Shed Steve

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    Karis, thankyou for reply. I think I shall get the clutch done, and worry about MOT later. I shall remember to get it good and hot as well!
     
  8. Belle427

    Belle427

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    high lambda readings without any of the other readings being high doesnt usually mean a sensor is shot. A leak in the exhaust system after the sensor can cause this
     
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  9. Avocet

    Avocet

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    I agree. Also, the lambda reading will vary with atmospheric conditions (air pressure mainly). The way it's supposed to work is that the lambda sensor detects when the mixture gets too rich (beyond a certain value) and tells the computer to give the car a bit less fuel. Then it keeps doing that until it gets to the "lean" pre-determined limit, and then starts to richen it up again. It just keeps doing that continuously, so the fact that you had a high lambda one year and a low one the next, doesn't really mean much. The point is, the sensor isn't letting it stray beyond those limits, so it's doing its job. To a certain extent, it even depends on whereabouts the mixture control is in its cycle when the gas analyser probe is inserted into the tailpipe. I'd definitely only worry about this if it actually fails.
     
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  10. Shed Steve

    Shed Steve

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    ch427 and Avocet, thankyou for the additional info., most useful, I now know more about these sensors! I feel happier now about getting the clutch done, I don't like scrapping cars which are still servicable and otherwise running OK.
     
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