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[laney101]

After some info.

On my 3.2 mv6 i always had issues with light being on (precat issue) decided for a change at 130k

I swapped to 3.0 downpipes but were copy cats no oem (poor quality i know) car went better  but cats rattled and light still on  so in the emd i decided go back to stock GM 3.2 downpipes.

Refitted but move second lambda boss post main cat. Whalaaa 10k later and still not had light on dash and no rattles from cats.

Now heres the issue.. since fitting them again (original Gm 3.2 pipes) definetely feels a lil down on power not as responsive and when it has a session of hard driving ( only has to be a mile or two) right under car where cats are you can feel heat standing by car it gets really hot. And has a slight smell.

Had this on other cars when cats are blocked or failing and wondering if it is a sign of the cats being past their best or just is what it is.

If they are due replacing whays best option. Do i buy approved new pattern cats.

Do i cut out gm cats and install sports cats in down pipe
buy 3.0 downpipes and have a o2 adaptor to move sensor aeay or something else ??

Any suggesstions or ideas be welcome

Cheers in advance

[BazaJT]

I don't know how effective[or not] or how expensive such products are but could you try putting something like Cataclean through the system to see if this improves matters before going the replacement route?

[laney101]

I use cataclean twice a year anyways bud ... doesnt seem to have improved it

[Doctor Gollum]

What fuel do you normally use?

[biggriffin]

Finding a set of decent 3.0/2.5L cats will be difficult, if your going for sports cats, then use the 3.0L downpipes you've alread modified,  Or buy a at of new pattern 3.0L and modify to fit 3.2... but try using a quality fuel for a week, and give it Italian tune up First.

[Enceladus]

Please confirm that it's the EML light and not the spanner light that's coming on. Are there any fault codes? You could try the pedal trick if you have no code reader? The lambda sensors themselves also wear out and get choked.

I'd be looking to find out what's triggering the EML before I started replacing expensive cats and sensors. For a start which side is it?

Check the date of 1st registration. If it's the 1st March 2001 or later then strictly speaking it's illegal to sell for, fit to or use a cat on the car that's not R103 type approved.

That said, type approved cats should be better quality than the non approved versions. They should have more platinum, iridium, palladium. The cat is supposed to be manufactured such that it performs at least as well and lasts as long as a factory original.

[laney101]

Indees hard to find genuine 3.0 ones.. yes that was plan install sport cats into the 3.0 aftermarket cat pipes ive got as lambda ports already been done.

Car since owned at 70k has never had anything other rhan shell v power in it... all thats used

Finding a set of decent 3.0/2.5L cats will be difficult, if your going for sports cats, then use the 3.0L downpipes you've alread modified,  Or buy a at of new pattern 3.0L and modify to fit 3.2... but try using a quality fuel for a week, and give it Italian tune up First.

[laney101]

No light is on please read my original post. EML was on for years probobly 6 or more always same code for the pre cat iasue the 3.2 has.

So eventually swapped to 3.0 cats (pattern ones ) stil had light on..

Went back to the original 3.2 oem vauxhall cats but moved sensor post main cat and since that never had eml on so thats fine and working.

What ivr got is it feel little bit lacking in power since they gone back on and when yoy do any spirited driving under car is stonking hot and you ca smell something.

When i have had this on previous other cars or friends have had it normally point to cats are clogged or on way out and not performing correctly.. thays what i was asking has anyone had this issue

Please confirm that it's the EML light and not the spanner light that's coming on. Are there any fault codes? You could try the pedal trick if you have no code reader? The lambda sensors themselves also wear out and get choked.

I'd be looking to find out what's triggering the EML before I started replacing expensive cats and sensors. For a start which side is it?

Check the date of 1st registration. If it's the 1st March 2001 or later then strictly speaking it's illegal to sell for, fit to or use a cat on the car that's not R103 type approved.

That said, type approved cats should be better quality than the non approved versions. They should have more platinum, iridium, palladium. The cat is supposed to be manufactured such that it performs at least as well and lasts as long as a factory original.

[laney101]

All shell v power petril station at top of road

If away from home always superunleaded wherever its from

Never had 95 octane in it

What fuel do you normally use?

[Doctor Gollum]

When was the cambelt last changed?

[laney101]

I did 5k ago.. was fine after belt change timing spot on used locking kit

[Doctor Gollum]

Any of the exhaust/any other work done at the same time?

[laney101]

Its nothing to do with cambelt...

It been since fitting the original downpipes its felt down on power...

Hence asking about the smell froming from cats and weather people have had this and sign cats are nackere

[Doctor Gollum]

I asked the question because you mentioned that it felt like it was holding back.

They run up to two teeth out and 1mm either way actually makes a difference to the performance. Hence ruling it out.

Were the aftermarket cats you fitted type approved?

[laney101]

I know bud as said thoigh i timed it and its bang on.. however i shall investigate once again to double check.. but  as said power lacking only since fitted original gm cars again.

The pattern 3.0 ones i did have on that still threw up Eml light couldnt tell you ... just 3.0 cats haha... know they were aftermarket as nothing wrote on them or no in built heatshields