MOT fail need help with emisions…

  • So every year my 3 struggles to get through the mot as the emisions wont pass, most of the time it scrapes through, but today he couldnt get it done. He said he tried telling the machine it was an older car, tried cheating one of the test but it failed the other, then the same the other way round.

    I asked if it could leave with the emisions of the fiesta that was sat there but he wasnt game!

    Anyway, its now running with a standard exhaust, new plugs, got a new lambda sensor on the way as well as a bottle of cataclean, another thing i noticed when I swapped the plugs was that they were covered in oil, im guessing that cant help things so I've ordered a RC gasket too.

    the other thing that was suggested to me was to fit the standard air filter, but I cant find it, would it make a difference?

    Anything else I can try, if all the above fails?

  • a good oil change would help. the airfilter shouldnt make much differance

  • oil was done about 1k ago, it was flushed too with that stp stuff. the car hardly gets used now, it only did 5k since last mot, most of that was Jan-Feb.

  • To get the emissions down you need new plugs, clean filter ( or remove totally for MOT but MOT only).
    Chuck a couple of tins of injector cleaner in and take it for a good burn down the motorway for an hour the same day or day before, the other thing is it could be the cat has had it and its worth just changing it straight away to be sure, even find a used one and try it
    you will also fail emissions if there is a slight leak on any joint in the exhaust system too

  • standard air box and filter will make a differnce. thats what i ould do but if you cant find it i dunno what to suggest. could try revving the hell out of it to clean anything out of the pipes and a oil change. try booting it in 2nd or 3rd gear until it hits the limiter hold it for 30 seconds or so and that should clean it out. dunno if it was god advice but a mechanic told me to do it a few years ago on my 306 and it worked

  • boo!!, mine fails also but my mechnic always uses the car next to it !!!, but if i got pulled for an emmisions check id be fooked!!.

    worth checking o2 sensors front and rear of manifold ?

  • only 1 manifold on it, 4 cyl

    I've ordered a sensor!

  • Have you checked the pcv and piping for possible clogging…

  • no, is that the little 90deg bend tube that comes from the valve cover?

  • @cea85142f6=jamesmx3:

    no, is that the little 90deg bend tube that comes from the valve cover?

    its the pipe rom the camcover to the induction pipe please correct me i wrong but pritty sure

  • thats the crank breather, the pcv is the bit on the front valve cover that is 90deg, im struggling to tell the difference tbh, from what I can piece together the crank breather sucks in filtered air through the intake tube abd the PCV then allows it back into the intake manifold plenum, took my pcv off tonight cos i wondered which way it flowed (since im not really sure on the system myself) and its flows away from the engine, ie, i could blow into it, but i couldnt suck through it.

    Which is what leads me to believe that the air is drawn through the crank breather, through the engine and then out through the PCV back directly into the intake manifold plenum. Someone correct me if Im wrong as I dont want to give bad info.

  • my mistake thanks
    :oops: :oops:

  • thought to ease any confusion i should just say that i was blowing into the pcv unit through the bottom of it, ie the part of it that sits inside the engine not the other end of it that has the hose running to the manifold

  • took the car in for a test again after changing plugs,exhaust sensor, RC gasket.


    Failed on emmisions, but only on CO this time, not Lambda(sp?) and head light aim and a OSR caliper not up to standard?

    So new cat on its way, and im a little confused on how the headlight aim changed from the last MOT, and how the brakes have managed to deteriorate in the 6weeks its been sat still?

    Ive had the Hbrake off and it left in gear. Grr!

    Was seriosly considering buying a new car, but then I thought if I can spend maybe £200 a year to get this through the MOT, then its not worth it! Considering Ive only driven 5k miles since last MOT.

  • In u.s they swear by product called seafoam. I'd be tempted to try that.

  • Dont think seafoam is available over here, never seen it anyway, probestore sells cataclean, seen that in both the local motor factors, £15, surely worth a try, many say its good.


    be handy if you knew someone with a emmisions tester to check before and after results before paying for mot re-test ( unless you dont have to of course. )

    Ive got to get my emmisions lower this year. Dont think they will use another car for emmisions for the 3rd year running!

  • I used a bottle of cataclean, got another one too!

    cat should be here tomorrow, and need to fix the calper and light, then try it next week!

    yeh wish there was a way i could test it before the MOT, problem is now its run out, I cant drive anywhere but to an MOT test!

  • youll be able to check it against the failed mot emissions values if you got a print out?


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