Replacement cats not fitting from BM

[Raggie]

Hello,
I am perplexed...I have a BMW Z3 1.9 M43/TU engine (at least this is what comes out with my VIN: WBACM12050LG23438, but I am beginning to question that) However, after speaking with BMW and giving them my reg (V801 GMJ) I am given the OEM part for a replacement cat of 1830 143 8090.
I have since bought TWO in the last week from suppliers of BM Cats, but neither of them fit, even though they have the same OEM number with their own reference number being 98023.
I have since talked to BM Support and a friendly man called Dave Anderson, who has gone through their stock to see if they perfectly fit in their jigs and he states they are a perfect fit.

So, my question is:

How can I have the only 2 non-fitting cats with the same OEM and BM part number?
Am I missing some fine detail for the fitting of my car?
Are there any other manufacturers of after market cats for my Z3 (specs above)?

I am at my whits-end as I now have to send the cats back to the seller, who, in turn sends them back to the supplier, who in turn checks them and then who eventually gets in contact with me to say whether or not there is a defect in the 2 exhausts which have already tried to be fitted by a mechanic-with failure-both times. The whole process will be at least another 2 weeks of the road and I need the car for work

Any help VERY welcome.
Thank you for your time to read this-I really do not know what else I can do...
Nat

 

[Nodzed]

Just a guess. Someone's fitted a different exhaust and or it's had an engine change. Check the engine number against the log book, later 4 pot if there was such a thing?

 

[Andyboy]

That's standard BM Catalysts I'm afraid. They all need heating and bending to fit.

Aftermarket cats are absolute junk. They last about one MOT test and that's your lot because they don't have the proper precious metals inside, hence why they're so cheap. What was wrong with the old one? If it was the original BMW one it's pretty unlikely to be bad. They are however a bit too far away from the manifold and can struggle to get hot enough to pass emissions. I've got a genuine Z4 2.0 converter here - you'd be better off welding that into the existing front section because it's going to work for years.

 

[Andyboy]

I may have a Z3 1.9 M44 cat - it was sold, and then it wasn't.
The manifold flange is different though.

 

[Raggie]

Thank you all for the above comments.
Nodzed: It is the original exhaust-I shall attach a pic. There is rattling inside the cat, so I am assuming the ceramic has come apart.

Andyboy: I recognise aftermarket cats are crap, I had (and still have) a 1998 Z3 which has a different engine, but managed to buy around 3 exhausts for this one-which fitted perfectly-but yes, last for 1 MOTish.
The M44 won't fit on my M43...Is there a work around or piece I could buy to make it fit and if so, how much are you looking for?

Thanks a lot to each of you for reaching out to help

 

[Andyboy]

£250 which is scrap value. The car it was intended for needs a catastrophic amount of work for the MOT or so I’m told. I’m going to look at it later to see if the garage are taking the p*** or it really is shafted.

 

[Andyboy]

This is a Z4 2.0i cat:

 

[Ianmc]

Good value that. A new OEM one is over £1300 now!

 

[Andyboy]

Bloody hell

 

[Raggie]

Thanks for the offer Andyboy, but it won't fit my engine as the end pipes towards the engine need to be longer:

 

[Ianmc]

it won't fit my engine as the end pipes towards the engine need to be longer:

Can't the end pipes be extended? IME only OEM cats are worthwhile for the M44 engine. Don't know about the M43 though. This would appear to be a cost effective solution IMO.

 

[Rudyrov]

You seem to be stuck between a wall and a hard place, are there not any alternatives with the Gov't (MOT) that you can pursue ?

 

[Andyboy]

Can't the end pipes be extended? IME only OEM cats are worthwhile for the M44 engine. Don't know about the M43 though. This would appear to be a cost effective solution IMO.

Well yes, a garage could cut and weld the M44 cat and M43 downpipe with a suitable sleeve. Just behind the lambda sensor would work. The M43 downpipes are longer due to the cast iron manifold.