Question about MOT emissions test...

[Tykey]

One for @JonRGV250 maybe or anyone else with relevant knowldege - I MOT'd my car today, it passed, but the MOT tester said it only just scraped through the emissions test. He said it was hard work getting it to pass it, I could hear him revving the engine quite a bit, not sure if related. He asked if it had a cat, I replied not sure but thinking about it I think it's been decatted iirc what the previous owner told me. He suggested for the next MOT it might be an idea getting a second hand (because of prices) cat fitted as "emissions are getting harder to pass all the time".

What are you thoughts about this? Are they really getting harder each year? I mean, if it passed this year, why not next year? Don't want to spend 100's on something I don't need. I'm keeping the car as I like it and it's given me no trouble so selling it is not an option.

 

[sovietspybob]

if you have a decat there is 0 change it'll have passed an emissions test.

if he had to rev it it could be the cat is dirty as they work best when they're hot but quite likely it might have a smaller 100 or 200cell 'racing' cat installed if its modded? those things need to be almost glowing red hot to pass emissions

Or like some cars that have 2 or more cats in the exhaust maybe one has been cut out just leaving one? Again it sounds like it'll be ok you just need to absolutely rag it to death for a long drive to the MOT place and make sure they do the emissions straight away. If it's not ticking like a bomb about to go off when you park it up for the test it's not hot enough.

 

[Rroff]

I dunno how much weather makes a difference on it - probably shouldn't too much as they tend to do it after the engine has been running awhile, though in my experience MOT testers actually make an effort to get vehicles to pass it for some reason - though that may be because I have a good relationship with the place I normally take mine.

Possibly running an additive through in the weeks before the MOT might help.

 

[JonRGV250]

One for @JonRGV250 maybe or anyone else with relevant knowldege - I MOT'd my car today, it passed, but the MOT tester said it only just scraped through the emissions test. He said it was hard work getting it to pass it, I could hear him revving the engine quite a bit, not sure if related. He asked if it had a cat, I replied not sure but thinking about it I think it's been decatted iirc what the previous owner told me. He suggested for the next MOT it might be an idea getting a second hand (because of prices) cat fitted as "emissions are getting harder to pass all the time".

What are you thoughts about this? Are they really getting harder each year? I mean, if it passed this year, why not next year? Don't want to spend 100's on something I don't need. I'm keeping the car as I like it and it's given me no trouble so selling it is not an option.

Petrol or diesel?
Assuming it is petrol, it’ll 100% have a cat or it’s absolutely impossible to pass the emissions test.
He’d be revving it to get it hot enough so it’s operating correctly, or if there’s a small hole in the exhaust he’d rev it quite high so it doesn’t fail on the lambda reading, that said he should hold the revs at “fast idle” 2500-3000 rpm and no higher.
If it’s a diesel, part of the test is revving it several times to meet the smoke/plate limit if it doesn’t pass first time.
Can you put up a pic of the emissions sheet?
I’m not sure why he said “emissions are getting harder to pass” if it’s a petrol as the limits have been the same for ages, diesels on the other hand are extremely strict now with some cars plate limits being almost zero.
Petrol cats tend to either work or not work, unless as mentioned it’s got a sports cat, then the tester needs it glowing like the sun to get it to perform correctly.

 

[jpaul]

yep - post-up your report ?
my previous mot emissions failure report & diagnsosis https://forums.overclockers.co.uk/t...ilure-maf-oxygen-sensor-vacuum-leak.18941959/

had had cat replaced on subsequent mot,
although last year hydrocarbons were up, he thought it might be burning more oil / blow-by, so, put in https://team.valvolineglobal.com/diy/product-tools/high-mileage-150k-faqs on last oil change,
I want to get a separate emissions test before this years mot.

 

[dave28]

REDEX £4.99

• Clean injectors.
• Reduce exhaust emissions.
• Restore performance.
• Increase fuel economy.
• Suitable for all petrol engines including hybrid
• Protects against E10 Petrol Corrosion

 

[Firegod]

One for @JonRGV250 I replied not sure but thinking about it I think it's been decatted iirc what the previous owner told me.

Don't want to spend 100's on something I don't need.

Not to be a d*ck but you've just admitted it has no cat. You need a cat on a vehicle, what is since 1995?... otherwise your car is illegal. It isn't something you don't need. If you want to do it right, stick a sports cat on there but even that might trigger a CEL due to the gasses passing quicker through than anticipated.

 

[SonicSW20]

Not to be a d*ck but you've just admitted it has no cat. You need a cat on a vehicle, what is since 1995?... otherwise your car is illegal. It isn't something you don't need. If you want to do it right, stick a sports cat on there but even that might trigger a CEL due to the gasses passing quicker through than anticipated.

In most cases yes, however there are edge case scenarios where you can have no catalytic converter and be 100% MOT compliant, despite the car originally having one.

 

[Armageus]

REDEX £4.99

• Clean injectors.
• Reduce exhaust emissions.
• Restore performance.
• Increase fuel economy.
• Suitable for all petrol engines including hybrid
• Protects against E10 Petrol Corrosion

I wouldn't bother with Redex, it's only half a step up from Snake Oil.

One of the only cleaners worth using is Wynn's Extreme Petrol Cleaner, in that it actually contains an ingredient known to clean fuel systems (PEA - polyetheramine)

https://www.amazon.co.uk/Wynns-Extreme-Injector-Additive-Treatment/dp/B01MRHV725

Wynns also do a specific pre-emission test treatment:

https://www.amazon.co.uk/Wynns-Pre-emission-Treatment-Petrol-Engines/dp/B084Z4GHNZ

plenty of discussion of additives here: https://bobistheoilguy.com/forums/forums/fuels-and-fuel-additives-gasoline-and-diesel.37/

 

[Firegod]

I wouldn't bother with Redex, it's only half a step up from Snake Oil.

One of the only cleaners worth using is Wynn's Extreme Petrol Cleaner, in that it actually contains an ingredient known to clean fuel systems (PEA - polyetheramine)

https://www.amazon.co.uk/Wynns-Extreme-Injector-Additive-Treatment/dp/B01MRHV725

Wynns also do a specific pre-emission test treatment:

https://www.amazon.co.uk/Wynns-Pre-emission-Treatment-Petrol-Engines/dp/B084Z4GHNZ

plenty of discussion of additives here: https://bobistheoilguy.com/forums/forums/fuels-and-fuel-additives-gasoline-and-diesel.37/

I like the Wynns stuff. Used some of their petrol addidtives in some older cars I've had in the past.

 

[JonRGV250]

Not to be a d*ck but you've just admitted it has no cat. You need a cat on a vehicle, what is since 1995?... otherwise your car is illegal. It isn't something you don't need. If you want to do it right, stick a sports cat on there but even that might trigger a CEL due to the gasses passing quicker through than anticipated.

It passed the emissions test, so it must have an OE or sports cat on it.
There is absolutely zero chance of it passing without one.
And if it wasn’t fitted it would fail for that reason anyway.
As for the CEL, you can fit an elbow extension which sorts it.

 

[sx_turbo]

If it does have a cat on it still, I have had great success with cataclean.

I used to sell it where i used to work, I had a couple of garages called about for cats on customer cars but the cost of the new cat was very expensive. The most memorable was a vauxhall omega 3.2v6 had twin cats on it and the customer didn't have the money for new cats not to replace the car. The car itself was rare when new.

I said to give this stuff a go, put it in tank fill up with fuel, drive it round for 500miles and then try emissions test again. Said if it don't work I'll refund it, phoned me up a couple of weeks later asking for another couple of bottles as they just had the car back and it passed flying colours. Wanted more bottles for another customer of theirs.

It doesn't always work, depends how far gone the cat is, however as yours just passed it should be able to clean it up.

Do need to confirm if it has the cat still though, which is likely as it would be close to impossible to pass the test.

That said however I know it is possible to map an engine to pass an emissions test without a cat. Manufacturers cannot do it because of longevity and repeat ability, they cannot spend time mapping each individual vehicle

 

[jaybee]

He asked if it had a cat, I replied ...

No, it died last year?

 

[Tykey]

Thanks for the replies so far guys/gals. Here's the ad for the car http://carsofsomerset.co.uk/product/2014-vw-golf-r/ which says it has a "Scorpion Decat Pipe" so this is why I assume it has no cat. I don't have the emissions sheet, it passed with no advisories so I only got the pass sheet.

I'm surprised the MOT tester asked me if it had no cat if the law is that one is required, surely he would know this.

Someone's gonna make me feel dumb now I bet and tell me a "decat" still has a cat!

 

[SonicSW20]

Thanks for the replies so far guys/gals. Here's the ad for the car http://carsofsomerset.co.uk/product/2014-vw-golf-r/ which says it has a "Scorpion Decat Pipe" so this is why I assume it has no cat. I don't have the emissions sheet, it passed with no advisories so I only got the pass sheet.

I'm surprised the MOT tester asked me if it had no cat if the law is that one is required, surely he would know this.

Someone's gonna make me feel dumb now I bet and tell me a "decat" still has a cat!

A 2014 Golf R should fail an MOT with a decat regardless of the numbers from the gas analyser.

Sounds like the tester was lenient and has given you a fair "off the record" warning to get it sorted for next time.

 

[JonRGV250]

As above, it sounds like he's given you a pass where he shouldn't have + a friendly warning, unless of course it's got a sports cat on, and thats why he struggled to get the numbers.
As for the emissions sheet, we don't have to give those to the customer (but we do need to keep a copy on site), and we're being encouraged not to hand out the actual MOT paperwork either, but tell the customer it's all online if they want to see it.
If it didn't have a cat, then..

My mate fitted a sports cat to his Golf R and no matter what I did I couldn't get it to pass, in fact a lot I've tested are pretty useless when it comes to getting a pass (other than they're actually fitted).

 

[Tykey]

So it looks like I'll be going shopping for a cat soon in preparation for next years MOT as I don't want to push my luck next MOT time with the garage (been going there for donkeys years always had a good relationship with them). Forgive the noob question I'm about to ask - will I need to buy a whole exhaust with a cat in it or just the part of the exhaust with the cat fitted (which I assume is the down pipe) and fit that to the existing exhaust? I'm going to buy second hand btw.

 

[Firegod]

So it looks like I'll be going shopping for a cat soon in preparation for next years MOT as I don't want to push my luck next MOT time with the garage (been going there for donkeys years always had a good relationship with them). Forgive the noob question I'm about to ask - will I need to buy a whole exhaust with a cat in it or just the part of the exhaust with the cat fitted (which I assume is the down pipe) and fit that to the existing exhaust? I'm going to buy second hand btw.

On my 595 I bought a decat pipe but then had the exhaust / tuner place cut and weld in a suitable size sports cat. If it turns out yours is part of a system to save money you could look to do something similar. Where the decat is now, cut out and weld in a sports cat. Appreciate the placement and size on the 595 means it is very easy to do.

 

[sx_turbo]

So it looks like I'll be going shopping for a cat soon in preparation for next years MOT as I don't want to push my luck next MOT time with the garage (been going there for donkeys years always had a good relationship with them). Forgive the noob question I'm about to ask - will I need to buy a whole exhaust with a cat in it or just the part of the exhaust with the cat fitted (which I assume is the down pipe) and fit that to the existing exhaust? I'm going to buy second hand btw.

I've had cars with cats removed for years, I've always been lucky working in the trade they've always managed to pass. Remember it only has to pass on that day in that 45 minutes.

Anyhoo, because of the remap I would be wary about just slapping a standard cat on. Knowing these cars when the cat is removed the cel light comes on, sometimes fitting a spacer on the lambda fools the ECU but not always, sometimes putting a decat on also causes the turbo to do funny things like "surge" making it difficult for the car to keep the boost under limits. So the best thing to do is have it remapped to sort all this out.... Which yours has done, looking at atlas tuning site they send the files away to be written according to the car data, so it is most likely the car was mapped with the decat in place.

So with that in mind I would suggest you don't just have the standard cat replaced, I would advise you have a sports cat installed into the decat pipe.

The sports cat shouldn't cause any issues with the map. However putting the stock cat in their definitely will cause some issues, and would require a remap / map removed

 

[JonRGV250]

So it looks like I'll be going shopping for a cat soon in preparation for next years MOT as I don't want to push my luck next MOT time with the garage (been going there for donkeys years always had a good relationship with them). Forgive the noob question I'm about to ask - will I need to buy a whole exhaust with a cat in it or just the part of the exhaust with the cat fitted (which I assume is the down pipe) and fit that to the existing exhaust? I'm going to buy second hand btw.

First off, check to actually see if it’s got a OE cat\sports cat fitted before anything else.
No point in buying one if it’s already got one fitted, and it’s not a 2 minute job to replace on your car.