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Discussion Starter #1 (Edited)
I've been told by BMW that my Cats are on the way out.

I'm not under warranty and want to consider non OEM items if the alternatives are better at all (price,power etc).

Can I legally run without Cats in the UK ? Has anyone ever done this ?

Any recomendations ?

The reason I want to replace them is that I'm down on power. I will try the MAFs first, but all the threads I've read on MAFs describe lost power as revs rise. I'm intermitent, but the other way arround, as the revs rise above 5000 she starts to come on song.
 

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stumbo said:
The reason I want to replace them is that I'm down on power. I will try the MAFs first, but all the threads I've read on MAFs describe lost power as revs rise. I'm intermitent, but the other way arround, as the revs rise above 5000 she starts to come on song.
If the cats were blocked, you would get the opposite effect; the higher revs mean more flow, which would get choked off. If the catalyst has been contaminated, it would not function as an environmental aid, but I doubt if it would have much effect on performance. If you have to replace anyway with non stock, have muffler shop temporarily weld in "test pipes" and see if that helps. I suspect it won't. If you go with bigger cats, check SS or talk to Bill @ Discovery Automotive or Vadim @ Evosport or Daniel @ Beastpower for replacements (all board sponsors!!).
Regards,
Jerry
Regards,
Jerry
 

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stumbo said:
I'm looking at the complete SS system front to rear and using [email protected].

Its an opurtuinity to leave the car with them for nice long health check.
Stumbo,

I've just recently got the full supersprint system, headers/cats/xpipe/backboxes etc.. and very very happy! I got the sport 100cel cats, and its all running sweet! :M5launch:

In the UK, you do need somekind of Cat system, as every car built after 1992 needs to pass certain uk emissions etc..by law, hence the emissions readout when you get it MOT'd.

Tin
 

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stumbo said:
I'm looking at the complete SS system front to rear and using [email protected]

Its an opurtuinity to leave the car with them for nice long health check.
stumbo, give me a call when youre ready for your Supersprint system. Im giving free shipping right now.

...As for the post above about non OEM cat, you cant beat our High Flow Metalic Racing Cats.

Give me a call.

Jason
 

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Too bad you're not in the USA. All mfrs warranty cats for 8yrs and 80K miles in the states per federal law. Not sticking my tongue out...just curious if there's a similar emissions hardware law in UK that may assist you.
 

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stumbo said:
......as the revs rise above 5000 she starts to come on song.
This does not sound like a cat problem. restrictive cats only display symptoms under high flow conditions (high RPM & full throttle). If your car runs perfectly normal over 5K RPM, cats are OK.
 

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Discussion Starter #11
Just to consolidate my findings as detailed in other threads:

1. Replaced x1 O2 sensor
>> This greatly reduced frquency of huge power loss.

[changed from Hexagon BMW Kentish town to [email protected]]

2. Replaced plugs and cleaned up oil grime coating them from slight gasket leak.
>> This reduced the quantity of diagnostic alerts and showed camshaft sensor as failure.

3. Replace camshaft sensor
>> This removed the problems (and alerts) at low revs.

4. Power loss at higher revs became more obvious - due to removal of other symtoms.
>> Left bank catalytic convertor diagnosed as partly blocked.

>> yup - gsfent your logic made sense even before Birds confirmed Hexagons diagnosis - and you were quite correct - I just couldn't see the wood for the trees.

Result: I've been persuaded by Birds to try to get to an OEM baseline before getting into mods (inc. exhaust). So will be talking to Tin about purchase of his old cats, after hes gone through MOT.
 

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If you end up needing cats, I heard that Bassani makes them for our beast and they're in the $100 range. At least worth a look.

Good luck, -B
 

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ELEVENS said:
If you end up needing cats, I heard that Bassani makes them for our beast and they're in the $100 range. At least worth a look.
Bassani?! Is this the same Bassani that made 2-stroke hop-up expansion chambers back in the 70's? Man, that pipe was like a miracle on my '74 TS-185 -- was a great Christmas present 30 years ago. ;)
 

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same people make some good exhausts for domestic applications....ive heard a c5 with their exhaust as well as a guy that used to do work on the m5 had a older body ford lightning with it.


they arent half bad
 

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CSBM5 said:
Bassani?! Is this the same Bassani that made 2-stroke hop-up expansion chambers back in the 70's? Man, that pipe was like a miracle on my '74 TS-185 -- was a great Christmas present 30 years ago. ;)
CSBM5 - Exactly my reaction when I heard it.

RIIIIIIIIIIIIINNNNNG DING DING DING DING !!!!!!


HAHAHAHA!

cherrsagai
 
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