MOT FAIL!!! Emissions

[bonnietiler750]

OK so how do get the emissions (CO) from 7 to 4.5 .
It is running standard Stromberg carbs
Any help much appreciated.
Cheers
Brian

[Jeff]

Didn't think they tested Stags on emission on MOT or have I got that wrong?

[Jeff]

Just copied this from the winternet.

Emissions
The emissions test for classics is much more tolerant than for modern cars. Basically, if there’s no visible smoke on tickover (with the choke off) and the exhaust doesn’t kick out excessive carbon monoxide, you should be OK. And if you your car is smoking out the MoT testing garage, it’s time to take remedial action anyway. Exhausts and manifolds should be hole- and leak-free.
My tester has never put a probe in my pipe and I know mine is running rich as I don't need much choke.

[Kithmo]

Vehicles first used from 1st August 1975 are meter tested and should be below 4.5 CO, before that just a smoke test.

[XFSTag]

I'm still recovering from the thought of a probe in your pipe Jeff

[bonnietiler750]

Yes that's my reading too so how do we adjust it to under 4.5 for the test even if I readjust after?

[KOY 23]

[Jeff]

Vehicles first used from 1st August 1975 are meter tested and should be below 4.5 CO, before that just a smoke test.

Ah yes, just found it thank you.

[rare1]

I run 4 classics and not one has emissions test take it somewhere different. Never had one fail MOT yet

[DJT]

I run 4 classics and not one has emissions test take it somewhere different. Never had one fail MOT yet

If they are pre-August 1975 then they don't need an emissions test. Just a check for visible smoke, as stated above.

[HersnotHis]

I run 4 classics and not one has emissions test take it somewhere different. Never had one fail MOT yet

Since AFAIK these aspects such as emissions of MOT's are on line computer driven these days I doubt that this is due to the test station. It appears that the OP has a post Aug 1975 Stag and therefore the less than 4.5 applies.

Other than suggesting that his Stag is running rich I can only suggest he uses the forum search as I remember this was previously discussed certainly within my 30 months of membership. However others may be able to provide a direct modus operandum.

H

[marshman]

Since AFAIK these aspects such as emissions of MOT's are on line computer driven these days I doubt that this is due to the test station. It appears that the OP has a post Aug 1975 Stag and therefore the less than 4.5 applies.

Other than suggesting that his Stag is running rich I can only suggest he uses the forum search as I remember this was previously discussed certainly within my 30 months of membership. However others may be able to provide a direct modus operandum.

H

I would think that ALL MoT stations now have computerised testers which tell the operator exactly what to do. When I take mine in he goes all through the motions of testing the emissions, i.e. enters the reg no. presses the "enter" key lots of times, forgets himself and picks up the exhaust probe then swears as he realises that the computer now says "PASS" end of test, and I laugh. Of course the tester can always choose to skip the emission test if he wants - I think they are supposed to file a printout but I know they don't always if the printer is "broken" - and just type PASS into the MoT computer. One day I suspect they will all have to be linked so the emissions tester talks to the MoT computer direct along with the brake tester so that they can't be "fiddled".

With regard to the original post, You have 2 choices:

1) Weaken the mixture to get it to pass the test - speak to the test station nicely and they might allow you to tweak it whilst you are there - its fairly quick and easy to do with the right tool (cheap enough from the usual suspects). At that stage all you want is the MoT and are not bothered if the engine runs "nicely" or not, Then once you've got your "pass" drive away and get it properly set up.

or

2) get it sorted properly anyway - i.e. service the engine - check the air filter, check points (if your have them), spark plugs, ignition timing, then set up the carbs -balance, idle and mixture. Simples. If that doesn't sort it then you will have to investigate further.

Roger

[Kithmo]

Yes that's my reading too so how do we adjust it to under 4.5 for the test even if I readjust after?

Effectively you have to weaken the mixture. Basics first, make sure the choke is fully off and make sure the engine is fully warmed up. Check that the carbs are topped up with oil and the rubber diaphragms are ok.

[Tdm]

in Tenerife no allowance is made for older cars - the emissions test is the same as for new cars.
My Stag therefore failed on an earlier test, but all I did was weaken the mixture (using the special carb tool to do so), and once the test was passed, richened it again so that it ran normally.

Fortunately I only have to have mine tested once every 5 years (not every year), so I have got to year 2019 before the next test is due and I will most probably have to do the same thing again.

[Seaking]

Remove air filter as well