Emissions Fail - Mot, Help Needed

[Patches 0]

Hi

 

My pug just failed as the Carbon Monoxide came out at 4.51% instead of the limit of 3.50%, now I dont dabble in this at all usually so this is a learning curve for me.

 

After searching the topics and having a good read through, it would appear that a simple tweak of the AFM 'could' be all that is required.. I have called a local garage and managed to blag myself use of their emissions analyser dooh dah for a tenner so I am off to do that tomorrow morning. So I guess I just need some very simple pointers of what do when Ive got the car on idle, which screw to turn and how far etc ( is it just a case of turning a few mm and doing another reading and same again etc? I have read it is the hex screw but mine appears to just be a hole with no screw in?! ( excuse my ignorance)

 

The only reason Im being overcautious is that I have read you can really bugger things up if you start tinkering too much with this without knowing what you are doing ( which I dont really), but Im guessing this is only if you do it when its not on idle therefore affecting the whole of the rev range?!

 

I should point out that the car has been smelling of petrol lately,,, could explain a few things huh!

 

 

Cheers for your help

 

Michelle

[Anthony 1,000]

Turn the mixture screw on the AFM anti-clockwise by about three turns and that should sort it out - with the engine running, you can normally do it by ear (to a point) as if you turn it too far, the engine note will change and start to sound a bit "chuggy" and the exhaust note will sound a bit more "hollow"

 

Shouldn't really need to use the emissions machine, but if you do, aim for around 1% CO or so

 

Just keep a note of how many turns you've adjusted the screw by, and you can put it back if you manage to completely screw up the idle - you'll not damage anything by tweeking the idle mixture though, so don't worry about that.

[Miles 331 1 Cars]

Or worst case just turn the idle up slightly which is allowed by the book and if that close they should have done it really

[Patches 0]

Anthony, thankyou , the only thing that is bothering me is, I can see the hexagonal 'hole' which is where I thought I would need to turn the screw, but I cant see a screw, its just a hole! ( Im assuming if I push the hex key in far enough it will turn a screw inside ( the light was poor when I looked)

 

Yeah, I just wanted it on a machine so as to ensure I am actually doing it right as it will be within the no charge retest period.. this time!

 

 

Miles - yes, I wasnt sure whether to adjust idle on its own, afm or both.

 

I get the feeling the MOT'er was an arse as he also failed me on my rear lenses being too dark.. in his opinion, no mention of them last time though..

[Coonper 0]

If the worst comes to the worst, you could put a cat in it from a later car. Then after mot, take it back out again.

[Anthony 1,000]

Anthony, thankyou , the only thing that is bothering me is, I can see the hexagonal 'hole' which is where I thought I would need to turn the screw, but I cant see a screw, its just a hole! ( Im assuming if I push the hex key in far enough it will turn a screw inside ( the light was poor when I looked)

 

Yeah, I just wanted it on a machine so as to ensure I am actually doing it right as it will be within the no charge retest period.. this time!

Miles - yes, I wasnt sure whether to adjust idle on its own, afm or both.

 

I get the feeling the MOT'er was an arse as he also failed me on my rear lenses being too dark.. in his opinion, no mention of them last time though..

The mixture screw is recessed in the hole somewhat - it should be there though. 5mm allen head bolt IIRC.

 

The mixture is too rich as it stands, no doubt of that, but there's nothing to stop you leaning it off and bumping the idle speed upto 1200rpm or so - should sail through then, but don't make it idle too high otherwise they can fail you on that.

[Patches 0]

The mixture screw is recessed in the hole somewhat - it should be there though. 5mm allen head bolt IIRC.

 

The mixture is too rich as it stands, no doubt of that, but there's nothing to stop you leaning it off and bumping the idle speed upto 1200rpm or so - should sail through then, but don't make it idle too high otherwise they can fail you on that.

 

 

Thankyou, again, much appreciated, Im less stressed now! Will pop a note on here after the MOT Friday to let y'all know how it went.

 

Michelle

[toffo24 0]

Thankyou, again, much appreciated, Im less stressed now! Will pop a note on here after the MOT Friday to let y'all know how it went.

 

Michelle

Hi Michelle

This might help you out as a mastertech at my local dealer told me this tip some years ago when i had my first GTI , Change the oil before you take it for a test and the emisions will be lower then running it on old oil , he told me that this is what they used to do when they had problems with the CO, might also help if you cant adjust the CO down to via the AFM.

 

regards

 

Peter

[jackherer 543]

If the worst comes to the worst, you could put a cat in it from a later car. Then after mot, take it back out again.

 

That wouldn't help, in fact 205 engine management would destroy a cat in no time.

[Simes 248 2 Cars]

As Miles said due to the age of the car the MOT testers can raise the idle up to 2000rpm to pass it through the test.

[Mikey S 29 1 Cars]

As Miles said due to the age of the car the MOT testers can raise the idle up to 2000rpm to pass it through the test.

 

 

thats more for A series engines that fail on hydrocarbons as they were a pig to get through the test.

 

im a tester and im surprised he didnt give it a tweak for you, i do if i get a pre cat car in for test and it fails on the emmisions, he must be a right miserable arse!

[C_W 3 1 Cars]

Anthony, thankyou , the only thing that is bothering me is, I can see the hexagonal 'hole' which is where I thought I would need to turn the screw, but I cant see a screw, its just a hole! ( Im assuming if I push the hex key in far enough it will turn a screw inside ( the light was poor when I looked)

 

If you can't see the screw head then it's probably still got its tamper-proof cap on which is like a soft lead cap that can be picked off.

 

As Anthony said unscrew it till it starts to falter and like Miles said raise the idle speed (screw on the throttle body - this again might have a tamper cap on if it's never been touched before).

 

It's also worth taking the car for a GOOD run, ie down the motorway for a bit in 4th gear just before you go in to ensure then engine and exhaust and oil is properly hot (rather than just water up to temp).

[richsmells 2]

As said adjusting the afm slightly would be first port of call. Then set idle speed, adjusting ignition advance if required/possible. I usually change oil before MOT and then get the car nice and hot before I get there.

 

Mine flew straight through this year and CO was just above 1%.

 

Hope you get it sorted

Edited May 21, 2008 by richsmells

[Patches 0]

Thanks all for the input, I will do most of the above!!! I wouldnt normally ask for blow by blow instructions but Im trying to look after my 10 month old at the same time as sorting the fails so its tricky!

 

Heres hoping..

 

Thanks again

Edited May 21, 2008 by Patches

[Patches 0]

Just a little, well big, thankyou once again, few simple tweaks of the AFM now have my emissions well below the limit, Im extremely chuffed.

 

 

Now Im cross that the MOT guy didnt do it, not sure where it stands on whether they should or shouldnt do something like that? I suppose if they do little jobs, then where is the limit and whats classed as a little job? But as I was hot footing it out of pug on the day of the fail, the guy behind reception said, 'its ok, we can look at it for you for £80 plus vat but we cant definitely fix it'...

 

I threw my head back and laughed like a f''ing musketeer....

 

Only due to the folks on this forum that I was able to walk away without being shafted though.

 

Wuv this forum

Edited May 21, 2008 by Patches

[Anthony 1,000]

Glad to hear that it's all sorted

[Hardgraf 0]

Good skills

 

A tank of 99ron & a bottle of redex helped get mine through

[Patches 0]

Lol - well its exactly a year to the day that I started this post and guess what........... just put her through the MOT and failed on... emissions being at 4.50%

 

At least I know what to do now!

 

Forum hug.

Edited May 20, 2009 by Patches

[jeremy 68]

Lol - well its exactly a year to the day that I started this post and guess what........... just put her through the MOT and failed on... emissions being at 4.50%

 

At least I know what to do now!

 

Forum hug.

 

This made me LOL. I hope the garage were more helpful this time.

[pug_ham 240 3 Cars]

Lol - well its exactly a year to the day that I started this post and guess what........... just put her through the MOT and failed on... emissions being at 4.50%

Did you re-adjust it after you'd got your MOT last year?

 

If not then maybe you needed to take it for a run as suggested by C_W on the way to the test centre & request that they do the emissions test first whilst its still hot.

 

Graham.

[Patches 0]

Yes I did re-adjust it.

 

I always take her for a run first.

[pug_ham 240 3 Cars]

Yes I did re-adjust it.

OK, I'd just set it mid way this time to get you through the MOT & leave it be. You're only changing the idle mixture & nothing else so I wouldn't bother resetting it again just to have the same fail point next year.

I always take her for a run first.

Cool thats what everyone should do before an MOT.

 

Graham.