32 replies to this topic

[Jim_Cross]

Cheeky, I don't think you replace it with anything. I think the pre-cat is a sort of absorbant material inside the pipe. They drill the material out, so you get a more freely flowing pipe. Hence you don't actually remove a section of pipe, so don't need to replace it.

[P11 COV]

vxchas Tried it but couldn't shift the rusty bolts on the silencer end of the exhaust pipe. Gave up in the end. How did you manage?

[Jim_Cross]

would you have to tell the insurence about this mod?
ohh bugger more expence:9mm:

This is probably the only mod I wouldn't tell them about. To find out about it, I guess they'd have to dissect the exhaust...not overly likely I wouldn't have thought.
Also, if it's pretty to explain a replacement air filter or god forbid and engine re-map, imagine getting them to understand what pre-cat removal consists of

[Loti]

Whatz the legal standpoint is it legal providing you can pass the MOT emissionz test ? Loti.

[goofballs]

errr....it won't......you'll need a friendly backstreet MOT man to get it past.

[cheeky_chops]

Well everyone reckons its fine - the precat is only measured at manufacture and not at the MOT

[Loti]

Me hopez this helps you peeps

The "Cat Emissions Test" is mandatory on all petrol cars first registered on or after Aug 01st 1992 (K) *see exceptions below*
BUT
at no point during any part of the MOT test does the tester have to check for the actual presence of a Cat. This is simply not a requirement.
The only requirement is that the vehicle has to meet the "Vehicle Specific Limits" which have been laid down by the VI and the Manufacturers.
This varies from make to make and model to model but as a general rule of thumb, up to Aug 95 0.5%CO and Aug 95 on 0.3%CO

All the emissions data is stored on a constantly updated emissions data card which is fitted into the 4 gas analyser, there is also a hard copy in printed book form from the VI.
The vehicle tested has to be an EXACT match to the data provided ie; Chassis codes and engine codes before the test can be carried out.

The test procedure is controlled by the Analyser itself, the tester simply followers this procedure until the end of the test, ie: engine temp checks, fast idle (around 2,600rpm) emissions test and natural idle emissions test.

If it meets the requirements of the designated vehicle limits then that car is a pass REGARDLESS as to whether or not it actually has a cat fitted or not.

*The exceptions to the rule have two levels of test.

a) Aug 01st 1992 - Aug 01st 1995 .... Test as non-cat test applying limits of 3.5%CO and 1200ppm HC

Aug 01st 1995 on ... Test as Default Cat Test applying limits of 60deg C oil temp, engine speed 2,500-3,000 rpm, Lambda 0.97 - 1.03, CO% 0.3, HC 200ppm

Exception Vehicles

1) CNG or LPG fueled vehicles - Test as (a)
2) Non Passenger Car (Has more than 5 passenger seats in addition to the driver and weighs more than 2,500kg ...ie; LWB Shogun or Civic Type-R ) - Test as (a) or ( depending on age
3) No EXACT match for vehicle / engine code found in database - Test as (a) or ( depending on age (eg, Mitsu FTO, BB4 JDM Lude VTEC
4) Vehicle fitted with different engine (eg - New Civic fitted withold CRX 1.6 16v engine) - Apply limits from engine age (in this case 1988 vehicle limits apply which would be 3.5%CO and 1200ppm HC) N.B It is up to the owner of the vehicle to prove the age of the engine.


Will a car intended to be fitted with a Cat pass an Mot then???
Some will yes.

As a side note (yes I'll shut up in a mo)

Did you know that

From cold the Cat does not work

Under full acceleration and deceleration the catalytic convertor is useless at actually stopping the harmfull gasses being expelled into the atmosphere.

Also while in stop start traffic the cat will cool down sufficiently to stop working.

Legal requirements are the same as Mot requirements in the case of emissions.

Loti.

[Jim_Cross]

But remember...this is the pre-cat, NOT the cat. So the Cat emissions test is irrelevant, it's the COLD START emissions test, as mentioned earlier in this thread, which will only apply to 2004 cars onwards (I think). So, it DOES NOT affect your MOT at all.

[cheeky_chops]

...and weighs more than 2,500kg ...ie; LWB Shogun or Civic Type-R ) -

... made me laugh anyway !!

[BogBrush]

I'm going to attempt this at the weekend. Wish me luck