1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Hi all, new member here with a problem...

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by pompeyal, Oct 30, 2010.

  1. pompeyal
    Offline

    pompeyal New Member

    Joined:
    Oct 30, 2010
    Messages:
    2
    Likes Received:
    0
    I have a 2005 A4 1.8t Cabrio which has just started to play up, I will tell you what has happened and what I have found so if anyone can shed a light on the problem that would be great...........

    Recently I went out in the car on a short journey (less than a mile to collect someone) just after leaving home the engine started to mis fire and shortly after the engine management light came on. Usually around 2000 rpm you can here the turbo whistle up but on this occassion I didn't here it. That may be a red herring. I got to where I had to go, switched off waited a short while then my passenger arrived and we returned home slowly, the car still mis firing. On lifting the bonnet I saw the CAT glowing rather hot (Bright orange CAT and Dull orange heat sheald). I have since removed the air filter so as to replace it and the plugs, Number One was still wet but not exessivley.

    Is there a way of checking the coil packs out of the car using a multi meter?
    Could the CAT have collapsed causing it to over heat? if not what else would cause this?
    Would this over heating damage the Lambda sensor and or the CAT?
    If the car was mis firing would any un spent fuel burn off in the CAT causing it to over heat?

    So many questions but hopefully some out there can throw some light on it, maybe this has happened to you.

    Anyway, if someone could help me and maybe give me some ideas on what and where to check it would be greatfully apprieciated. AL.
    #1
  2. BASS 666
    Offline

    BASS 666 BMW aye right dead on..

    Joined:
    Sep 23, 2010
    Messages:
    463
    Likes Received:
    1
    looked this up for you..


    It's NOT clogged (yet) and it's not "doing it's job." A cat normally gets very hot when in use, but NOT GLOWING hot.

    Something is causing raw unburned fuel to be sent down the exhaust pipe where the cat "burns" this fuel. The cat is designed to burn the tiny amount of unburned fuel that comes from a normal engine. Now, if you pour excessive hydrocarbons (fuel) in the exhaust, the cat will burn that too and since it's burning too much fuel it glows red hot. This won't last very long, this is very damaging to the cat. The catalyst can get hot enough to melt. And that won't take long! And when it melts, then you will have a blob of molten metal blocking the exhaust pipe (now it's clogged!) and the engine will stop operating. At that point, the only fix is replacement of the catalytic converter.

    However, if you find and fix the problem now you can avoid that expense. You have to find why raw fuel is going through the engine. The most common reason would be a bad spark plug or bad spark plug wire. If the spark doesn't work, there is no "combustion" in that cylinder and the raw unburned fuel goes out the exhaust pipe.

    A spark plug can be replaced for 0.97 cents, but if you wait till the cat melts, well those can cost £100's or more to replace.

    Other problems could be a bad carburetor mixture, bad computer causing overly rich mixture, clogged fuel injectors, even bad /burnt valves and/or rings but heck lets not think about that.

    But get an expert to look at it NOW and don't drive it any more till it's fixed, or that cat will melt and then you'll be in deep do do.

    Good luck.
    #2

Share This Page