Catalytic converter help

[likedatyalll]

Ok Let's start with my 740i has 391,XXX miles. Today my SES light came on, scanned the OBD and bank1 cat below efficiency. I refuse to remove the cat and dunk it in soapy water, add catalytic converter cleaner to my gas tank, or any other shade tree mechanic advise.

So, with that said, what was the solution people have found for the cat appearing to go bad? Factory or aftermarket (brand).

[Timm]

There's a few choices - but on a car of the E38's age the usual plan is to have an aftermarket pair of cats fitted - you can squeeze a bit more power from the engine using 200-cell cats (they reduce back-pressure compared to the usual 400-cell versions) - but you let a bit more noxious gasses through. As a ball-park, aftermarket cats (which are welded in by a custom exhaust specialist) are around a third of the price of OEM.

[BimmerFlyer]

Ok Let's start with my 740i has 391,XXX miles. Today my SES light came on, scanned the OBD and bank1 cat below efficiency. I refuse to remove the cat and dunk it in soapy water, add catalytic converter cleaner to my gas tank, or any other shade tree mechanic advise.

So, with that said, what was the solution people have found for the cat appearing to go bad? Factory or aftermarket (brand).

I just bought a '97 740il that was in need of a pair of Cats... price from BMW was $1300 a piece...Ended up with a pair from Magnaflow thru Bavarian Autosport.... nice quality, fitment was OK, they might be just a little bit louder then the factory ones, but not in a objectable way. Not as big and heavy as the factory originals for sure... I ended up spending a little bit more for the 50 state version, even tho I do not have inspections of any kind..I kept reading that the M62 is kinda a "dirty " engine and that longevity on the cheaper Cats( less material) was not good..and I did not want the Engine light to come on in 15000 miles..
This is from a newbie..so take it for what it is worth..
Pete

[georgebest]

I have just installed these MagnaFlows a few months ago. No change in sound, all cylinder misfires are gone. Seems price went up a bit, it was below $100 when I bought it.
Strangest of all: the original ones looked in perfect shape after we cut them out. Maybe it was something internally.

[jclausen]

I have heard some folks using spark plug adapters pulling the post car oxygen sensors out of the exhaust stream to fool the system

[likedatyalll]

After some research, I have decided to go with the magnaflow direct fit catalytic converters.

Other than government compliance in CA and NY, is there truly a difference between the CA and NY compliant cats and the ones that are noncompliant?

Will my 7 throw codes (SES) if I purchase the non CA and NY compliant cats? I live in GA and if I can save a few $$ on non CA and NY compliant cats I'll do it if it won't cause a problem.

[likedatyalll]

Well, finally got the MAgnaflow (direct fit) cats and installed them. The cats were much lighter than stock and fit very well. cranked-up the car and she sounds great. We will see if she throws any codes. I will keep those interested updated.

[BimmerFlyer]

Well, finally got the MAgnaflow (direct fit) cats and installed them. The cats were much lighter than stock and fit very well. cranked-up the car and she sounds great. We will see if she throws any codes. I will keep those interested updated.

How well did they fit? When I mounted mine, the right side fit perfect, the left side on the other hand not so much.. even tho it hooked up correctly between engine side and muffler side, it did drop down significantly below the frame rail.( the right one did not) almost looked like some of the pieces were not welded in the right position....
Pete

[jaysonx]

How well did they fit? When I mounted mine, the right side fit perfect, the left side on the other hand not so much.. even tho it hooked up correctly between engine side and muffler side, it did drop down significantly below the frame rail.( the right one did not) almost looked like some of the pieces were not welded in the right position....
Pete

I am running these cats and have the same issue. My left exahust pipe hangs below the frame rail, and scrapes on occasion (car is lowered).

[BimmerFlyer]

I am running these cats and have the same issue. My left exahust pipe hangs below the frame rail, and scrapes on occasion (car is lowered).

I went round and round with the people at Magna flow, send pictures and measurements, that never really went anywhere. They did not seem to interested in the problem, and I got tired of dealing with it... next time I have it in the air, I will cut the pipes and re weld them back together correctly..not what you want to to with a $500 pipe, but thats the way it goes..
Pete

[likedatyalll]

Not one issue. Sorry to read about the issues you guys had with fitment. Maybe the guy that made my set has a 740i . Mine is lowered on KIDOS rolling on 19's and fits well.