MOT failure emmissions!!

[T88CAN]

Had my 97 chim 400 in for mot today it failed on front wish bone(no surprise there)and emmissions the co is 3.5% i think they said the car has just come out of hibernation i had to recharge battery and then checked it over before giving it a 10mile run it was running ok but not perfect as my nearest dealer is 40 miles away i took it on recomendation to a Rover dealer the guy there is in his 50s and works on a 350i so better than "fred in a shed" there does not seem to be any info in "the bible 1 ?"ANY surgestions or help please what can i expect? the garage is going to check a few things tomorrow and i will try and get a wishbone it took 3 months last summer! TONY

[pebbledash]

My Griff was at that sort of value when it last went in for MOT. Ranted the Proverbials off it to get it nice and hot (which it was), but after poking around for a while found the problem, basically it had a slight misfire which was dumping enough fuel into the cats to put everything out of kilter. so another blast later (I like to use the petrol not burn it revving the car up) and it just passed the test had to be done manually (i.e. take the gizmo out of full auto mode) and even then the high idle had to be at its highest to pass. Also had to put the fans on so they did not switch in and out which also caused it to fail a few times.. Have had it rechecked since and now its all fine..

[malloryn]

Most probably requires a new catalytic convertor.
What was the CO reading from the last MOT?. A high figure could have indicated the cat was on its way out.

What was the HC level this time - a high figure here would indicate unburnt fuel - misfire.

Another possiblity could be a faulty lambda sensor - what was the lambda reading.

[T88CAN]

Neil did you get my e-mail/photos?? TONY

[GreenV8S]

Could be a manifold leak making the lambda sensors read excess oxygen so the ECU richens the mixture to compensate? Or misfire, excess fuel pressure, faulty sensor somewhere. Or just a cold cat. They're big and seem to need a lot of heat into them to work properly.

[rbfisher]

Had the same problem on my chim. Solved by putting new plug shields on. Use the genuine Vauxhall ones - more expensive but last longer apparently.

[malloryn]

Did not receive the photos. Could you re-send

[T88CAN]

Thanks for the replys folks emmissions sorted a melted wire on one of the lambda sensors! luckly i had a spare from when i changed the manifolds my decision to use the Rover guy seems to have paid off took him less than an hour to diagnois (he kept calling the chim a 3.9!!)any way ive just picked up wishbone so should have it back for the weekend then time to sell(97 P prowler purple 42k 12 months mot!! 14k any takers??)
Whats the liklyhood of having the same problem on both my tivs!! thanks again

[T88CAN]

Its back but what a crappy day for a run! just posted the advert will try to clean it up over the weekend will be sorry to see it go after 2yrs