Passing MOT Emissions without Pre Cats.

RichRS6 · Passing MOT Emissions without Pre Cats.

As the title really.

When I was an MOT tester we had quite a few cars which were completely de catted which could still pass emissions testing.

Anyone managed to get their Audis to pass emissions without pre cats ?

calibra_se8

My S4 passed the MOT fine with just the main cats.

amanda

I have been told if the car passes the emmisions they are not bothered if it has cats on or not.............ie they don't look for them

bam_bam

Image edited out by DavidT because it is not work friendly.

I might know of a place where catless cars pass MOT.

KiwiRS4

Passed with flying colours, no cats.......just 100% Tesco 99 goodness. Maybe they've got some additive that plays Jedi mind tricks on the VOSA box.

StumpyRS4

Get the car/zorst nice and hot

loomx

pre-cats are for warm up mainly anyway. So any car with cats and pre-cats will pass with pre-cats removed.

BennyBoo

Just find out your MOT tester's favourite tipple

s4balljoint

RichRS6

I don't recall any requirement for vehicles to be fitted with any cats for the MOT so long as they pass the gas test.

It seems like (judging by the responses here) theres a good chance of them passing without the pre cats so long as it is warmed up correctly.

Cats always seemed to be a waste of fuel to me as a restriction in the exhaust system they reduce the efficiency of the engine so you use more fuel to get to the same speed.

They may reduce some of the (so called) greenhouse gasses but mean we are all burning more fuel which can't be good for the environment or for oil reserves.

So if they're removed have any of you seen any MPG increases ?

loomx

Just cheat and fit a load of fake exhausts...

"The MOT limits prescribed relate to the total exhaust gas being emitted by the vehicle.
If a vehicle has a dual exhaust system, then the emissions from the tailpipes should be averaged. This is done by adding together the readings and dividing by two, eg
1st pipe emits 6% CO, 400 ppm HC
2nd pipe emits 4% CO, 500 ppm HC
Average CO reading is
6+4/2=5%
Average HC reading is
400+500/2=450ppm
The Results of this type of test must be entered manually onto the VTS Device."

So if you normally have a dual exhaust and you fit a fake or vacuume operated twin on the other side that was closed in the test you would get

6+4+0+0/4 = 2.5%
400+500+0+0/4 = 225ppm

On another note, running it lean will reduce the CO and HC output, but your NOx will shoot up... although I am not sure if NOx are tested in the emissions test.

guymcc

Quote...'The Results of this type of test must be entered manually onto the VTS Device."

So is this the way round no cats at all, ie he will enter in the figures that are required for a pass!???

AliGod78

Sorry to Hijack, but I'm looking for a sympathetic MOT station in the south... tyres on 1.6mm or there abouts... and I'm broke!

RichRS6

AliGod78

s4woody

The emission tes that I perform at my testing station doesn't require it being entered into the VTS.
If the vehicle fails you enter the reason and if it passes then you keep one print for the VT40 and the other goes to the customer with his pass or fail cert depending what else it has failed on.
Cats need to be red hot to pass on an old not used very often type of car..
Looking for the cat/precat is not part of the MOT test

sis200sx

hey woody arnt they on about bring ing that in to the mot though as they are on about the cheap and shit HID kits you can buy off ebay if you have them fitted to a car that did not have them from the factory and dont have the headlamp washers and the front and rear headlamp aim auto adjusters on the suspension arms/system arnt they gonna be a fail soon??

si