MOT Fail - CO Emissions

[peteyg]

 

The Esprit has failed her MOT for the first time on emissions. They've never been tested at previous garages but took her to a different place today and the result was CO of 4.93% with a max limit of 4.5%.

 

Can I get away with crancking in the mixture screws to reduce the reading? I know she runs rich anyway. I did take her for a good blast before the test.

 

Never had to cross this bridge before...help!

 

Pete

[jonwat]

Can I get away with crancking in the mixture screws to reduce the reading? I know she runs rich anyway. I did take her for a good blast before the test.

 

Never had to cross this bridge before...help!

 

Pete

Yes, they're just testing the emissions at idle so best to use a colourtune to set the idle mixtures correctly. :-)

I had an S3 fail once and the miserable old git of a tester told me I had to take it to a main dealer to get it seen to. Half an hour later & I was back demanding my free retest which of course it passed :-)

[Mike6]

Make sure as well that oil is fresh and air filter has been changed. These can make a big difference to the readings

[Mark Blanchard]

I always get mine serviced before the MOT. It's never failed. Geoff at EE always makes sure it passes .

[GordonMasson]

Strange.... My S1 has just been tested and they said they don't check emissions on a car that wasn't built to adhere to them... makes sense to me.

However, my 1968 Vitesse failed on emissions at a different garage and the tester prated around with the carbs to get it through but it ran like a pig afterwards. I wouldn't mind but the carbs had just been tuned and it was going like a train!

Perhaps we need to get a definitive answer on it?

[peteyg]

According to the MOT info only pre August 1975 cars are exempt from the emissions test.

[slewthy]

You could try adding some Wynns pre-MOT emmisions reducer?

Got mine at Halfords for a few quid and was so far under the limits, tester suggested I had it running too lean.

 

First MOT without it - right on the limits. Next 2 with, well under. 

 

Just a thought.

[910Esprit]

Turn in the mixture screws by 1/4 turn on each carb, that should get it down by 0.5%    Luckily I've got a very understanding MOT station locally and we go through this pantomime every year to get mine under the bar  

[molemot]

Being part of the Mechanic's Mafia helps...I get comments like "You don't want to run THIS too lean, do you?" Considering the tiny mileages that our cars do, it's pretty irrelevant I reckon. Paying £225 a year for the nasty polluting Lotus that does 3000 miles a year, and much less for the wonderful Volvo diesel that does 12,000 and thus pushes out much more overall.... as Steve says, it's a pantomime.

[peteyg]

The irritating thing is not having a gas tester at home so can't see what difference I'm making by adjusting the mixture etc. Have better things to shell out over £100 on just to get through this test as I'll be going back to the old garage next time.

 

Thanks for the advice all.

 

Pete

[jonwat]

Then spend a tenner on a Colotune.

http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_170260_langId_-1_categoryId_255216

[910Esprit]

Assuming your current mixture and balance is 'balanced' across the 4 chokes,  1/4- 1/2 will reduce the co by around 1/2%  - Speaking from experience not hypothesis! 

 

Why not find an indy garage and explain what you need to do?   All they need to do is run the emission test before booking you in.   Sure they would be happy for a few quid.  If they won't the next one will.....

Edited April 17, 2014 by 910Esprit

[Sir Paolo]

Fortunately I have a sympathetic Mot tester who races cars so isn't going to give me any grief over CO. He did tell me once that the hydro carbon levels were v high (he still didn't fail the car), but this was caused by a faulty spark plug.

[peteyg]

SHE PASSED

 

Well sort of. Cleaned the air filter and turned the mixture screws in 1/2 a turn and the reading was down to 4.6% CO but the tester took pity on her and so now we're legal again! Heaven knows what  else woiuld need to be done to lower the figures further?

[Simon350S]

Last time I really struggled with a car I 'introduced' an air leak post carbs whilst the tester was watching the screen, worked a treat and once he whipped the pipe out I put the vacuum hose back on naughty boy hey.