*Glenn* 854 Report post Posted April 15, 2009 WARNING If you car has pre cat and after cat oxygen sensors YOU CANNOT REMOVE THE CAT Quote Share this post Link to post Share on other sites
pjay 8 Report post Posted April 15, 2009 The cat will die without oxygen. Don't do it peoples Quote Share this post Link to post Share on other sites
Greg111 13 Report post Posted April 15, 2009 Engine won't know what fuel ratio it's using hence it will go lean and melt valves and top of pistons. Not good. Quote Share this post Link to post Share on other sites
E30BMA 0 Report post Posted April 16, 2009 Systems fitted to M52 and some M54's are open loop systems so they do not do dither the fuel delivery. I think Glenn was just warning people in general, not specifically talkin about M52/M54's. Personally I wouldnt risk it on any car fitted with a Catalyst. Theyre there for a reason and Ive seen plenty of cars have issues once theyve been removed. Quote Share this post Link to post Share on other sites
westy 614 Report post Posted April 17, 2009 That may not work either. I have a 2000 328 here with precat sensors only! Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted April 17, 2009 That may not work either. I have a 2000 328 here with precat sensors only! You sure?? The other 2 are probably up in the manifolds... I'll check on Monday .. I still have the chassis # on file Quote Share this post Link to post Share on other sites
M3_guy 0 Report post Posted April 17, 2009 So if I have an 1994 e36 M3 I shouldnt remove my Cat System??? Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted April 17, 2009 WARNING If you car has pre cat and after cat oxygen sensors YOU CANNOT REMOVE THE CAT Did you not read this M3_guy ?? Quote Share this post Link to post Share on other sites
M3_guy 0 Report post Posted April 17, 2009 Did you not read this M3_guy ?? Sorry I dont know what is a pre cat and does e36 m3s have o2 sensor after that cat? Quote Share this post Link to post Share on other sites
westy 614 Report post Posted April 17, 2009 You sure?? The other 2 are probably up in the manifolds... I'll check on Monday .. I still have the chassis # on file The 328 Glenn. Not the 330. Its South African. Has some oddball features. Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted April 17, 2009 Sorry I dont know what is a pre cat and does e36 m3s have o2 sensor after that cat? E36's as a rule dont have after cat oxygen sensors Quote Share this post Link to post Share on other sites
E36 2 Report post Posted April 17, 2009 Out of interest, what sort of hp gain is possible by removing the cat? (1995 M3) Cheers Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted April 17, 2009 Out of interest, what sort of hp gain is possible by removing the cat? (1995 M3) Cheers Very little...unless they are blocked or partially blocked Quote Share this post Link to post Share on other sites
nastnas 9 Report post Posted May 18, 2009 how can you tell if the cats are blocked? Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted May 18, 2009 (edited) how can you tell if the cats are blocked? 1999 cars and later, you can check with a scan tool and read oxygen sensor values in live data...pre cat / after cat Pre 1999 cars you can only diagnose when they effect performance and cause other faults to occur Edited May 18, 2009 by *Glenn* Quote Share this post Link to post Share on other sites
MLM 57 Report post Posted May 19, 2009 Slightly OT, but i stuck my head uner my car and it does not have an o2 sensor?? (92 318is manual) i can find the plug under the body which is blanked as is the relay under the bonnet next to the fuse box. I have heard e30's have o2 sensor so why wouldnt mine asuming newer technologies and ecu control? Quote Share this post Link to post Share on other sites
nutter 1 Report post Posted May 22, 2009 Heythere you guys probably will know this and laugh but on my 1991 e34 525i M50 motor theres no cable or sensors that i can spot after my cat does this mean its a pre cat sensor and would it hurt my Betty if i put my home made exhaust on ? 2" dual pipe staight throw from the manifold to a proformence euro style Tip/Muffler(well dont know if it proformence one) bought because my mate put one on his M20 an it sounded !@#$ING mean lol.And a few people recon it will be to loud for wof(deal with that once its on) Yeah im sorta a Noob with Porformence parts and upgrades LOL Quote Share this post Link to post Share on other sites
ieasti 0 Report post Posted June 22, 2009 what about for an e46? does removing the cat provide any power? Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted June 22, 2009 what about for an e46? does removing the cat provide any power? You cant.... let me say, you will do damage to the engine Quote Share this post Link to post Share on other sites
CamB 48 Report post Posted June 23, 2009 You cant.... let me say, you will do damage to the engine Without meaning to be difficult, in the whole wide internet I can't find any evidence this is the case. You'll get a check engine light for catalyst below threshold, but the second sensor doesn't appear to be part of the fueling decision making by the ECU - it seems to only have the task of determining if the cat is working properly. I'm happy to be proved wrong (and would really love to know for certain one way or the other). The wife's Skoda has a P0420 code because it has a highflow APR downpipe and cat, and so far the engine hasn't blown up in the approx 20-30,000km since its had the code. Quote Share this post Link to post Share on other sites
jordyboy2 0 Report post Posted June 23, 2009 what about for an e46? does removing the cat provide any power? Alot of the americans do it, weather or not its good for the car, I dont know Heres a link that might help you if you want to get rid of the code CamB Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted June 23, 2009 The wife's Skoda has a P0420 code because it has a highflow APR downpipe and cat, and so far the engine hasn't blown up in the approx 20-30,000km since its had the code. Youve still got a cat there Quote Share this post Link to post Share on other sites
CamB 48 Report post Posted June 23, 2009 Glenn, yeah it does still have a cat, but my thinking is that whether its there or not, the ECU thinks it isn't so will be doing whatever bad stuff it is that you are worried about. Thanks for the link jordy - that's my current plan, but would prefer to absolutely know for sure what OBD-II does with the signal from the second sensor before I start fooling it. Quote Share this post Link to post Share on other sites
ieasti 0 Report post Posted June 23, 2009 Is it true that american e46s have their cats in their headers? and our european spec ones don't? Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted June 23, 2009 Is it true that american e46s have their cats in their headers? and our european spec ones don't? Some of our models do to Quote Share this post Link to post Share on other sites
