failed mot(emissions)

  1. L-plater Joined: Oct 2008 Posts: 53
    #1
    my vts failed it mot on emissions the tester told me its likely to be a problem with either lambda sensor,coil pack or plugs as it does run a tad lumpy its like the revs drop every now n then on idle then pic's back up to normal, so today i replaced the plugs and found 2 of the plugs to be coated thick with engine oil.
    it was the 2plugs closed to gearbox,could this be a headgasket problem or just coil pack? the car doesnt missfire at all through out the rev range when driveing and i have had no overheating problems.thanks sy
  2. Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.
    #2
    Sometimes the rubber rocker cover seal leaks(8v`s)& oil drips down on to the plugs,so check that 1st.A coil pack wouldn`t put oil on the plugs.Don`t rule out blocked injectors either as a cause of lumpy running,i`m getting it at the moment & the car nearly failed the emissions test 2 weeks ago because of it.(injector cleaner)
  3. Frequent Poster Joined: Jul 2010 gateshead Posts: 807 vw golf GTI citroen saxo forte 02 plate vw polo
    #3
    how often is it serviced, does it burn oil?
  4. L-plater Joined: Oct 2008 Posts: 53
    #4
    i have only had the car a few days so don't know it burns oil,the coil pack has got a crack on that yellow resin stuff on the top would this affect the running?
  5. Regular Poster Joined: Aug 2010 Posts: 330
    #5
    Did you buy it with no mot
  6. Established Member Joined: Oct 2009 exeter, devon Posts: 1224 Clio 172
    #6
    my car failed on emissions yesterday, CO level too high, so i changed the lambda sensor. it passed, but runs like utter shit now
  7. L-plater Joined: Oct 2008 Posts: 53
    #7
    yea brought it with out a mot,could the coil pack be causeing high emissions? is there any way off testing the coil pack for falts?
  8. Regular Poster Joined: Aug 2010 Posts: 330
    #8
    i was going to say try new plugs,but i see you have.
  9. Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.
    #9
    Quote:
    Originally Posted by sy84 View Post
    yea brought it with out a mot,could the coil pack be causeing high emissions? is there any way off testing the coil pack for falts?
    Well put it this way if the coil pack is faulty then the engine will be struggling & possibly using more fuel making the emissions higher.
  10. L-plater Joined: Oct 2008 Posts: 53
    #10
    i managed to get hold of a second hand coil pack from local scrap yard fitted it today and no change also striped down the throttle boddie and cleaned all idle control valve etc and still no change so gona try a new lambda sensor tomoz,gettin expensive now tho
  11. L-plater Joined: Oct 2008 Posts: 53
    #11
    i fitted a new lambda sensor today managed to get the hc levels down to a pass level but the engine still hunts now n then and the co levels are to high to pass i when to scrap yard a got some new temp senders cos the guy at the garage said it could be them causeing the problem,fitted them but engine is still hunting has ne one got ne idears what else to try?
  12. Saxperience Forum Bum Joined: Jun 2011 Abermule, Mid Wales. Posts: 2763 Corsa Rally Car & Fiesta ST
    #12
    leak in the inlet manifold somewhere?
    sucking in to much air so sending more fuel in to compensate so running rich and causing co2 to be to hight maybe.
  13. L-plater Joined: Oct 2008 Posts: 53
    #13
    how wld i test for air leaks on manifold?
  14. Saxperience Post Whore Joined: Jan 2008 ..... Posts: 5231 ..............
    #14
    spray wd40 around the inlet whilst running, see if you see any bubbling...

    did you buy a brand new lambda?
    a slight air leak would cause your idle to get higher not drop, unless u had a massive air leak which i doubt.

    what year is your VTS? single plug or three plug ecu?

    But to help you loads
    Change the map sensor
  15. L-plater Joined: Oct 2008 Posts: 53
    #15
    yea brought lambda sensor new.yea the revs only drop but will try that with wd40 any way,its r reg so belive it wld b single plug ecu,will pop to scrap yard tomorow and grab a map sensor,its driving me mad now seam to spending alot off money now
  16. Saxperience Forum Bum Joined: Jun 2011 Abermule, Mid Wales. Posts: 2763 Corsa Rally Car & Fiesta ST
    #16
    stop getting replacement parts from the scrap yard, if your having to do the trial and error thing with random parts to find out whats wrong, second hand parts arent really guna help much are they, they to could be nackered like the oones youve already got.
    get to the motor factors and buy new ones, especialy little sensors and the likes cause there not that deer.
  17. L-plater Joined: Oct 2008 Posts: 53
    #17
    just got back from garage they did a diagnostic check and all sensors are working corectly as they should,the garage fink it could be down to the cat even tho the cat looks quite new,the back box isnt that grate its broke up inside,gives a rattle when reved and can here rattleing when i hit the back box with my hand,would a poor back box cause the co to be high?
  18. Established Member Joined: Feb 2004 Gloucestershire United Kingdom (England) Posts: 1261 VW Golf GT TDi 170 BMW 320ci 1988 mk2 Golf 16v
    #18
    If the plugs were covered in oil, could be oil seals/dodgy piston rings?

    My bros old golf had this, we used that 'stop leak' stuff and it passed after that.

    When you revved it hard you could see smoke though, does yours do this?
  19. L-plater Joined: Oct 2008 Posts: 53
    #19
    nah its doesnt smoke at all