fuel/air mixture

  1. L-plater Joined: Mar 2010 Chesterfield Posts: 41 2000 'X' 1.6VTR
    #1
    hey all,

    just wondered if someone could enlighten me!!

    what is the best way to check or signs of the engine not getting the right fuel/air mixture?

    engine management light came on few weeks ago with the CAT reading as the fault, I've fitted a new cat and the lamdbas' look in good shape I don't think they were changed long ago, the light went off and the car has being running a lot better. However after cleaning the car at the weekend and cleaning the exhaust as I usually do I've noticed after just a few days there is a build up of black crap around the inside edges (more so than usual, as it was very noticeable to me) the car isn't smoking however it does idle funny mainly after reversing, it bounces between a thousand revs and nearly stalling.

    its a 2000 mk2 vtr.

    any help would be greatly appreciated.

    Rich
  2. Regular Poster Joined: May 2009 Posts: 425 2001 Furio with Mk2 Vtr lump 2001 Vts
    #2
    plug it in mate lamba sensor would be giving off a bad reading if its not running the right ratio
  3. Saxperience Hardcore! Joined: Oct 2005 Aycliffe Posts: 32205 Saxo VTS
    #3
    Hi Rich, the idle is going to be the Stepper Motor (ICV), sounds exactly like the symptoms associated with a sticky Idle Control Valve, so your first step to addressing it giving it a good clean - There's a link the Engine/Performance Section the 'Sticky's' thread containing a guide to cleaning the device.

    Regarding the air/fuel mixture, the black crap doesn't seem like anything out of the ordinary, however it's not a reliable method of determining whether the a/f mixture is wrong. You're better to take a look at the condition of the spark plugs, they should have a fine, light, grey appearance around their tips if the mixture is true - if they're all dark then the a/f mixture could well be out. keep an eye on the mpg over the next few days/weeks and determine whether the car is drinking more than it should be.

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  4. L-plater Joined: Mar 2010 Chesterfield Posts: 41 2000 'X' 1.6VTR
    #4
    thanks for the replies, I wondered if giving the ICV the once over would make a difference but I haven't got round to it yet, I will get it done tomorrow as i have some spare time.

    I'll also go and get the emmissions checked to make sure everythings alright there.

    If I am getting the wrong f/a mixture what sort of things should I be looking at to be causing the problem? Any chance just a good service will sort it out? sorry if it seems a silly question maybe the answer is quite obvious, I'm ok with changing parts and general DIY mechanics just not so sure when it comes to fault finding lol

    thanks again for your help, hopefully its nothing too serious
  5. L-plater Joined: Mar 2010 Chesterfield Posts: 41 2000 'X' 1.6VTR
    #5
    Fuels definatly not good guys, went to pick my gf up from work yesterday, its approximately 82miles round trip of motorway, used nearly half a tank, I wasn't thrashing it either all but 2juctions worth of driving is 50mph average cameras for road works!

    Any ideas why its drinking so much??
  6. L-plater Joined: Mar 2010 Chesterfield Posts: 41 2000 'X' 1.6VTR
    #6
    Cars getting worse now, when I start the car now if I don't catch the revs it will stall, the bouncing revs is constant and I've found if you are maintaining a steady speed with your foot just pressing the accelerator the car is very jaulty, as if there is a misfire, but if you accelerate a little more it goes. Could this still be dodgey spark plugs/coil pack, or possibly a throttle sensor somewhere packing up?

    I would really like to get this sorted quickly if someone could advise me what to try please?

    Rich