My car is a VW polo GT 1991 J reg. (early 91 I guess) I 'll get the exact date if necessary.
When were cars compulsorily required to have cats?
So a car from before this date fitted with a cat from new can have the cat removed and still be ok for the MOT? It would then be tested as a "non CAT" car.
Please explain how the ECU would handle this situation.
Any benefits I might expect, apart from a less stressful MOT test for the car.
Any disadvantages, except environmental ones.
Thanks
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Not sure if this helps or not, but taken from the testers manual
www.motuk.co.uk/manual_730.htm
Information
Early catalyst vehicles:-
The flowcharts and notes must be carefully followed. If a vehicle is fitted with a catalyst it does not necessarily mean a 'CAT' test is required.
B. Catalyst test
1. The exhaust emission test
The catalyst test is part of the MOT test for most class IV spark ignition petrol engined passenger cars with four or more wheels first used on and after 1 August 1992.
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Please explain how the ECU would handle this situation.
Same as before,but if a problem exists with any sensors, doing away with cat is not going to help the engine ie other problems may crop up
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Steve
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Looking at a publication entitled 'Volkswagen and the Environment', they say that cars up to 1400cc (yours) must have a catalyst installed by the 31st of December 1992. I don't know if this date was ever changed after publication.
Assuming it wasn't, I would guess that all cars registered for use before this date, do not need to have their emissions tested as rigorously, catalysts or not. So I?m guessing that you could remove it and still pass the MOT. I'm basing this on the stories I?ve read about people removing them in favor of performance exhausts which make-do without the catalyst. Someone on here better qualified, will be able to confirm that aspect for you.
Providing the lambda probe was still installed correctly, I think the ECU will never notice it?s gone. The ceramic body within my catalyst broke up into little chunks not so long ago, effectively rendering it ineffective and it still ran ok. (If you ignored the clanking from all the broken bits within the pipe!)
I don't think there would be any noticeable benefits in removing it, you might get a tad more performance but I would expect this to be negligible. As for the MOT, it won't matter because they won?t be testing it. But someone in the know will say for sure.
Probably just as worthwhile leaving it in place.
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Ok, so it appears the car should not be put through a cat test anyway, that's good news and something for me to watch out for in the test.
I'm not really interested in performance, but if the exhaust should need replacing it might be cheaper to use a non cat exhaust. I dunno how I'd get the Lambda sensor to work though. Just thinking out loud here. Ta for the replies.
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When were cars compulsorily required to have cats?
Were they ever? Many will need a CAT to get through the tests, but some can certainly pass without a CAT, so would they have to have one?.
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I know someone with an old Audi (H-reg?) who removed his cat and said it ran like stink afterwards. I can't see it doing any harm, the lambda is before the cat and so removing it just increases the airflow.
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Mike Farrow
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removing the cat,should really not affect the gas flow unless it has collapsed.its only in place to convert exhaust gasses to water vapour when it has warmed up,lambda sensor tells ecu whether engine is running too rich/weak so the ecu will compensate, if all sensors are working correctly.then a motor without cat may pass.but only if at certain year.. failure of one or more sensors will mean ECU will not operate correctly so even without cat some may fail MOT
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Steve
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Strictly speaking I don't think there is a "cat test" as such. It is simply that (most) cars registered after 1992 or whenever have to pass more stringent emission levels. Most are made able to do so by having a cat fitted (plus lots of other sophisticated controls, sensors, etc), so the absense of a cat on a pre-1992 car would not alter the test that would be applied - it would simply be the appropriate test for a car of that year.
It may well be true that some cars even without, or pre- , cat, could pass the later test anyway. I got an 89 carburettor Volvo through its test a couple of years ago, and noticed that the emission levels recorded would actually have been just low enough to pass even the later post-1992 levels. Not bad considering I had tuned the carb by ear using just a screwdriver.
I have read several articles on cat removal on pre 92 cars. The consensus is that it is vital to keep the oxygen sensor in place in the pipe. That means either in its original place in an empty, cleared-out cat, or in a special socket welded into the substitute section of pipe.
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You need a cat (or an extremly clean engine!) from K-reg onwards.
Earlier cars just have to meet lower emissions standards.
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Just to complete the picture and be strictly correct, there are a very few post-K reg cars that were granted special exemption from the stricter emission rules. This is explained in the small print on the notice in an MOT test station. I think these were either cars with very limited runs, or those old models nearing the end of production that were impossible to clean up enough.
I don't think Trabants, for example, can pass the full test.
Also, if you fit an older engine into a post 93 car, it is only tested at the level applicable to its original date (if documented).
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If you?re thinking of removing the Cat, then this may be of use to you:
cgi.ebay.co.uk/VW-Volkswagen-POLO-GT-De-Cat-Downpi...m
Its nothing to do with me incidentally, just thought it may be of use to you.
May be worthwhile checking to see if it allows for the connection of the Lambda probe.
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If you decide to get rid of cat,make sure the downpipe is capable of accepting the oxygen sensor.if it isnt,ecu will remain for the time being in manufactures spec,ie it should give a warning something is wrong.and may cause problems as time goes on,as it is not connected
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Steve
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