M52 without catalytic converter

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schnaarf
E30 Zone Camper
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Post Wed Jan 30, 2013 6:39 pm

guys,

Getting mixed messages on t'internet about running an M52 without a cat.

Currently the M52B25 is in an E39 but it'll be coming out. At the moment I believe it has an o2 sensor post cat, so wont this mess up the ECU readings? At the moment the cat is knackered. So, do I replace it or do they not really have an effect on the running of the engine?

I have also read that these engines respond well to a bit of back pressure from the cat...

Views on the above?!

Cheers
eko
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Post Wed Jan 30, 2013 8:21 pm

Mines got no cats,runs fine and passes emmisions fine :D
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schnaarf
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Post Wed Jan 30, 2013 8:24 pm

nice :thumb:

not sure what to do about the sensor but I'll see what happens if i disconnect it!
eko
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Post Wed Jan 30, 2013 8:29 pm

Should be 2 sensors,one on each manifold.
Keep them in place.
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schnaarf
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Post Wed Jan 30, 2013 8:35 pm

think there's only one (no.8) here:

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eko
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Post Wed Jan 30, 2013 8:45 pm

Ah im talking about M52B28 which has the 2 manifold mounted sensors.
Not so sure my advice is right for you now to be honest although I dont see why it would be a problem?
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DanThe
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Post Wed Jan 30, 2013 10:27 pm

Some M52's did indeed have only one sensor, ive seen it on a couple of Z3's but not had a good enough look at the loom to see if the standard 2 sensor job can be used in place
Either way I wouldnt be going to the trouble of fitting a cat
schnaarf
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Post Wed Jan 30, 2013 10:30 pm

right, bollocks to it. I'll get the cat opened up, take out the filters and stitch it back up.

Will report back!

thanks