Hi, my 525 is registered 01.01.92.  Am I right in thinking I can get away with removing the Cat?  If I do is there any improvement in power or mpg and is it easy enough to do?  I probably won't do it anyway, I'm just interested if anyone else has tried. 

Thanks

Andrew

Im looking at doing mine aswel, also wanting that Viper2 chip when I can find time to go down and have it done, hows your car with that chip then mate ? mines a '91 model so same engine I do believe.

Also looking at those Stone Brother Racing header pipes, they claim between 15bhp and 30bhp extra power - 200 quid on ebay atm

The all important cut off date is 01.08.1992. Ref source http://www.buypartsby.co.uk/catalytic_mot.php - www.buypartsby.co.uk/catalytic_mot.php

Cars registered before 01.08.1992 do not need to have a cat fitted to pass the emissions tests. 

Cars registered after 01.08.1992 need to have a cat fitted to pass the emissions tests.

Removing a cat is bit of a pointless exercise in cars registered before 01.08.1992 because you will need to faff around with the engine management settings to cope with the different exhaust back pressure, for example you don't need a lambda sensor anymore.  You will need a straight thru replacement pipe that bolts in the gap left from the cat or a complete new exhaust.

I had a 3.0i 24v Vauxhall Senator before which had twin cats (£700 worth if they went belly up!) but as mine was registered on 04.09.1990 it didn't need them for the emissions test.  Other Senator owners talked about removing them and fitting them with two straight pipes of the same length, they reckoned the power gain was about 10% or 20 bhp but if you didn't remap or re programme the ECU to run without the cats it would cause bother later. And sorting the ECU on such an old car isn't worth doing.

It's a lot of work to do it properly for not much gain so it's up to you.

Andrew

Removing the cat will make a slight difference in performance, as the exhaust gases will flow through the system easily.

You will not need to make any other modifications if you remove the cat.

Do not remove the 02 sensor, as you will put the engine management system into open loop all the time and will be overfuelling it.

The o2 sensor has no bearing on whether you have a cat fitted or not.

The o2 sensor senses oxygen in the exhaust gases, and adjusts the mixture accordingly.

The cats job is to burn of any excess gases as they are passed through it.

Once a cat reaches operating temp, the monolithe lights, and as the exhaust gases pass through it, the dangerous ones are burnt of.

Whether it has a cat or not, the o2 sensor still has to manage the engine fuelling.

cat just finishes the process of.

Hope this helps.

Regards,

Gordon

Thanks for the advice Andrew & Gordon, I think I'll leave the car as it is though its good to know that if the Cat ever gives me any bother I can just remove it. 

The Viper 2 chip has made a noticeable improvement to the car.  When I first installed the chip I went out for a blast, first impressions where that there was not really any change but later I took the car for a longer drive and was really surprised with the difference.  The car feels a lot more responsive and pulls a bit harder from low revs.  I managed to drive the car for four miles on the motorway keeping the mpg thingy on the dashboard above 30 varying my speed between 50 & 70 (up and down hills).  This would never happen normally.  I have just done 140 miles on £20 of petrol @ 84.9p per litre which I think is pretty good for my car considering in the past I have had it well down below the 100 mile mark!

I don't know anything about the Stone Brother Racing header pipes.

Or you could just knock out the cat's insides, then you'll be cat free and won't need to replace the pipe. Quite a few modern turbo diesel owners do this for better turbo spool up and the cat sin't required ona diesel for an MOT.

And as said you won't need to adjust ECU settings as the lambda corrects fuelling whether cat is fitted or not.

Yours is too new kbannon. Has to be made/registered before August 92. So unfortunately you need to get a new cat.

Whats wrong with your cat?

I have seen some stuff called Cat Back (I think) which is added to the fuel and supossed to recoat the cat with the 'special' metals so it works again - not sure how affective it is, but they offer a guarantee!!

I figured it wouldn't work! Forgot about the car test!

My cat now sounds as if it is well and truly broken with a spluttering/marbley noise. The car feels as if there is a constant rev limiter fitted onto it. Last week whilst driving up a ramp to a motorway I overtook a Pug 206 but it took a real long time to do it!

Cat was finally replaced today. Haven't been able to drive the car since it decided that 2k revs is way too much!

It feels absolutely marvellous now. Power, performance, everything. I had obviously become used to the restriction on it (prior to Sundays tantrums!).

Only problem is that I have to cancel Christmas as it set me back €1118 @ a main dealer! I thought it was originally going to be about €800 or 900! Still the lighter wallet reduces weight in the car improving the power/wright performance!

kbannon wrote: Only problem is that I have to cancel Christmas as it set me back €1118 @ a main dealer! !

 Oh my god!

kbannon wrote: Savo wrote:  Oh my god! My words exactly!

Was that when you handed the cash over to Kelvin and he grinned back at you, how much of that was for labour?

Topazman

kbannon wrote: Only problem is that I have to cancel Christmas as it set me back €1118 @ a main dealer! I thought it was originally going to be about €800 or 900! Still the lighter wallet reduces weight in the car improving the power/wright performance!

Oooooouuuucccchhhh   Sorry to hear that Killian, I was wondering how you were getting on with your knackerd cat just yesterday.  

Thats about £800 I reckon.  Sure your original quote of 800-900 Euros wasn't in pounds sterling?

Did they smile nicely at you when they took your money?  It does make parting with that amount of cash so much easier!  NOT!

Does the Mrs make you feel guilty about having to fork out lots cos its a BMW after making you feel guilty about forking out lots to buy the sodding car in the first place?  Or is that just mine?

Andrew

kbannon wrote: She hasn't said anything in fairness about the cost of the cat. However, she is female so she will!

Yeah but have you told her exactly how much it cost? 

There is no point fibbing to them how much it costs, they find out in the end, they always do.

I just honestly tell her, saves the turbo strop and whinge later when the bank statements come in.

Andrew

kbannon wrote: as it set me back €1118 @ a main dealer!

Ouch indeed!  I better start saving for mine!  Just out of curiosity Killian, why did you decide to go main dealer rather than source it through ECP, GSF, etc?

kbannon wrote: it set me back €1118 @ a main dealer!

Je$u$ H. I got a price from my local tyre & exhaust centre for about €600 for a Bosel one and I laughed at that.  Drivin' on with the noise for a few more months.  Probably would have got it done by now, only budget blown on replacing the tyre/rim and suspension/steering arms last few weeks and the xmas shopping for the 2 little toxics.

Local indy is on the look out for a used one for me but will only take it he knows the car and there are only less than 40k on it.  TBH, I might bite the bullet after xmas when the bonus gets here and get one from GSF.  Their cost for one is about €385 inc. VAT and my indy will fit it for about €100.

Dergside wrote: Ouch indeed!  I better start saving for mine!

Are these common things to go on the E39 then?

Should I start saving for mine too then?

Andrew

Andrew Rolland wrote: Dergside wrote: Ouch indeed!  I better start saving for mine!  Are these common things to go on the E39 then? Should I start saving for mine too then? Andrew

Andrew,

I've heard the mileage mark of 80k being bandied about for the time they generally tend to give up.  Mines on it's 2nd one but previous owner decided to go the cheap route and welded in a spurious cat that looks like it's only suitable for a smaller engine car.

It's holding out for the time being .... just noisey on cold...but gets better after 20 mins driving.  Still I have to get it replaced in the new year but I'll be steering clear of the $tealers.

Killian, what was the discount for?  Club membership?

Andrew Rolland wrote: Should I start saving for mine too then? Andrew

Eventually they'll need replacing on any car.  Don't think that its an e39 or BMW related issue, just that they'll die eventually.  Its the price paid for spurious fuel, push starts, splashing through standing water, etc. over the years.

My Beamer only has 52000 miles.  30000 miles of saving to go then.

I had two of the blighters on my 3.0i 24v Senator and when I got rid of it (for my Beamer) they were the original ones, 14 years old with 98,000 miles of exhaust gasses battering them.  I asked how much they were when I was replacing various bits of the exhaust and they were 350 notes each.

Mind you my Sennie was too old for the cats to be part of the MOT test.  Just as well maybe as 1 cat cost more than I got as a trade against the Beamer!

Andrew

I just recently replace both cats on my E39 535i V8 with metal cats (i.e. not ceramic).  The ones replaced were the originals and the car has done 130k so not bad going although the metals cats do cost slightly more.  3yr warranty etc.  All in (including two new lamda sensors and all fitting) £750.  Not too bad I thought.

E34 ones tend to last longer, not sure why, maybe because they cost more than the E39 ones??