failed MOT

[mattykimbo]

The last time i used my camper it ran too fast on idle, I took it to my garage who owns a few carb engined cars himself. He reset the carb settings and tuned it, said it showed 1.7 on c02 so well within limit.

Today 3.5 months later taken the vehicle for an MOT, I've not driven it for a long time as ive been off work following an operation. The vechile flew through the mot for everything except emissions, the HC was perfect but the Co2 was 7.9 where its meant to be 3.5 its a 1990 1.9 watercooled petrol

Any ideas how it can of gone from 1.7 to 7.9 when I've literally driven it home from the garage at 1.7 and parked it up for a few months, and what i can do to fix it? he said it left a bit of a black sooty deposit (smoke not yellow hand puppet) on the floor

thanks

matt

[tforturton]

Did he run the engine until it was properly warmed up, before taking the reading?

[mattykimbo]

I dont know to be honest, i left the camper with the garage at 8 then went to work, the mot garage is about 2 miles from the garage i took it to so i doubt it would be hot by then. i thought they normally revved them a bit to warm them up first . not being there though i cant be sure

[Asw]

At our last MOT the comment was "it's emissions are horrible when cold but after 10 min they were really good, an easy pass"

[mattykimbo]

I think I'll have to take it for a thrash then to mot test station whilst hot see if that works, it's been stood for 4 months which I doubt helped!!

[California Dreamin]

As part of the MOT the tester is supposed to use an oil temp probe before checking omissions...the oil temp has to be 80C or higher before testing. For this reason I doubt he got it wrong.
A blast and fully warm engine would definitely help but I'm wondering if something has happened to your choke (typically snapped the pigtail off the bi-metalic spring) and the choke flap is 'floating around instead of properly closing.

Martin

[mattykimbo]

In all my years watching a tester test my cars I have never seen them use a temperature probe to check the oil, normally just watch the temperature gauge leave the car running whilst they check the rest over then test the emissions. As i wasnt there not sure if this happened.

Last night I collected the van from the garage on my way home from work when i started it up it was cold and letting out the black smoke, smelt petrolly. I took it for a thrash on some back roads when i got home and it was hot (so hot you couldnt really put your hand in front of an exhaust) there was no smoke and it smelt fine, i took the air filter housing off the carb and the butterly was operating as it should be. Im just wondering if its a build up of cabon as ive not used it in months and wasnt sure if an additive would help clear it up.

[marlinowner]

Below is taken from the mot testing manual. There is no mention of oil temperature. Might be worth changing the oil, if it's contaminated with fuel that can cause high emissions. Also check air filter isn't blocked.

"The engine must be at its normal idle speed and
operating temperature when checking exhaust
emissions.
Engine speeds and temperature can be assessed
either subjectively or by reference to
manufacturer’s or other reliable data."