de-cat mot

[Cymru1]

need some quick advice...

I think my car is A1 for the MOT apart from the de-cat, whats the best option to run to get the "cleanest" emmision test...... 95 Uld, Super, or Super + octane booster? it's a 94 ABY so should have the cat installed, just hope I get a decent "tester" not one who does everything by the book!

Thanks for any input..

[Jamo]

Non of them will get you through the MOT test for a pass. A de-catted S2 will always fail on CO2 emission in comparison to the cat values.

There was a thread on here that claimed that if it failed on the cat test the machine should automatically default to the non cat values and the car will then pass.

I haven't seen any evidence to back this up so it's at your own risk.

[s2driveruk]

has it previously passed the MOT test with them installed? in theory it would never pass as the emissions would be out of spec for the year/model as the car would be subject to the later version of the check rather than the basic one which preceeded it. Might be ok with a tester prepared to turn a blind eye but i'd fully expect it to not pass.

If you are going to try, i'd be making sure i had new sparks, oil, good quality fuel and basically get it mighty hot from a good thrashing before i went near the test station

Good luck

David

[s2driveruk]

beat me to it Jamo....

[s2driveruk]

useful link: http://www.vosa.gov.uk/vosacorp/repo...01992-2002.pdf

[Sonic]

As i understand it there is a maximum emission value that your car has to perform under.

Mine has a milltek sport-cat and passes with flying colours, im not sure about no cat though. I would recommend giving it a real good thrash before taking it to the test though.

A mate almost failed his MOT on the emissions as the value was way above the maximum even after they'd taken it out for a warm-up. He took it out for a spin and it passed with flying colours when he bought it back.

[GT500]

tried mine last time, shame there was a honda parked near it and for some strange reason the probe fell into that after mine failed by miles!
I would say you have no chance!

[Jamo]

Interesting link there S2 driver UK!

[dubmeister]

need some quick advice...

I think my car is A1 for the MOT apart from the de-cat, whats the best option to run to get the "cleanest" emmision test...... 95 Uld, Super, or Super + octane booster? it's a 94 ABY so should have the cat installed, just hope I get a decent "tester" not one who does everything by the book!

Thanks for any input..

On my machine it does a "fast test" first - CO= <0.2, HC= <200 ppm, Lambda=<1.03
Then if that fails the settings change to CO=<0.3. the others staying the same.
It has to get below all these figures for the fast idle(>2500 rpm) and idle tests.

All yours should fail on is the CO reading as thats what the cat controls/lowers- if it fails on HC then thats a fuel/spark issue and Lambda a hole/leak in the exhaust.

After Nov '08 all MOT emissions machines HAD to have the updated database, or they could not test with that machine.

Get the car nice & warm, make sure the oil, plugs and filter are new or clean(It does make a BIG difference.....)
Good Luck
Head down to Swansea if you want a proper test done:mischeif:

[s2driveruk]

will a car that has been thrashed prior to an emissions check be likely to pass then? Also do the HC/CO readings stay low even if the car is then left to idle on the ramps for 15mins while the other test items are covered off before the emissions check is completed?

I've always made sure the fan is cutting in and out frequently before parking up for a test to be sure it's nicely hot (and the brakes too) so that there is less chance of a duff reading.

[Rusty]

Modern 100CPI sports cats aren't restrictive so might be an idea to get one fitted and ditch the centre section to maintain flow and sound. Doesn't help this time round but saves faffing about next time, I used to have a de-catted '94 Golf and MOT time was such a pain, couldn't be bothered with it now.

[KaraK]

A mate almost failed his MOT on the emissions as the value was way above the maximum even after they'd taken it out for a warm-up. He took it out for a spin and it passed with flying colours when he bought it back.

To follow up on what sonic says, the car in question was my '02 scooby and it has a partial de-cat (as std there are two cats, one in the down pipe and one in the centre section - mine has the centre section one removed)

When they tried to test the car intially it had only done a couple of miles from cold to the test centre and it failed the C02 miserably. They suggested they wanted to try it "warm" but their mechanism for doing this was to run it at 2.5K for 5 mins. Shockingly enough it still failed miserably (in fact the value had gone up - it was now reading 0.5ppm) When I pointed out this wouldnt do jack for it I persuaded them to let me take it out for a run, they looked at me like I was stupid but a 10 minute blast up and down the A-road later and it was re-tested and read 0.02ppm

I don't know how well this method will work for you since you don't have any cats left as the key thing for mine was to get the remaining cat up to temperature so it could do its job.

[dubmeister]

will a car that has been thrashed prior to an emissions check be likely to pass then? Also do the HC/CO readings stay low even if the car is then left to idle on the ramps for 15mins while the other test items are covered off before the emissions check is completed?

I've always made sure the fan is cutting in and out frequently before parking up for a test to be sure it's nicely hot (and the brakes too) so that there is less chance of a duff reading.

Always better to get the car at a good temp(cooling fan cutting in etc) BMWs are a nightmare on emissions and will only pass when the car is HOT

Cars that do a lot of town/short trips need to have the ****** thrashed out of them to get anywhere near, Rover K series engines are really bad for this- no matter what they are in- 25s,45s,freelanders etc- and then the head gaskets go!!!!!!

You can't really leave the engine idling when it's up in the air as spinning wheels with the engine running car fook up the ABS system.............

The CO/HC reading usually are worse at idle than at 2500+ rpm.......... cars will pass the fast idle and then fail idle miserably..


A car that wont pass the emissions 1st time can add at least 20 mins to the test...
Which is why some testers can't be arsed to help to get it through..............

Top Tips??

Make sure that the oil/filters and ignition system is up to scratch.

Give the car a damn good thrashing before hand to blow all the **** out of the engine and exhaust (Doubly important if you do a lot of stop/start journeys)

Then just worry about the brakes and steering

HTH

[Cymru1]

Good News, It Passed!!

[Jamo]

Scan the emissions test if you can! Seems the defaulting of the test maybe true interesting