I have a 2003 Mini Cooper S i have owned since new. At 20 years or so I needed to replace the exhaust manifold as the flex part was leaking, so I went with a cat less setup. I am now considering giving the car to my daughter, who lives in Wisconsin, where they do emission checks every two years. Right now the car throws a CE light due to the lack of a cat in the header (the exhaust cat is still there). Do I need to go back to OEM to get rid of this light? OEM exhaust manifolds are 2k plus! Or is there another way to get this done, either with a tune or some other exhaust header.

Looking forward to the advice of the collective.

 

code out post cat O2 sensor. @adriancl on this site can do it for you remotely

 

I installed a Milltek header/exhaust manifold with high flow cat last weekend. I have driven about 300-400 miles on it with no check engine light so far.

My emissions are due in November but we can test 90 days prior, so I got the pass with my stock manifold and cat before I put the Milltek on in case there was an issue.

FYI - I have the Milltek resonated catback exhaust already on my car and the header made my exhaust about 25% louder since there is no precat in the Milltek header and the pipe diameter is 10mm wider than stock. I heat wrapped my header and so far, I am very pleased with it.

 

There is such a thing as an O2 Simulator, when wired in, will make your system believe that the post-Cat sensor is putting out the correct value. Remember, if the inspection station inspects for a Cat and there's not one there, you have a problem.

 

From the perspective of an auto mechanic, doing that to a car driven by a "normal" person - someone who just wants to drive their car to work right and get them around - could be problematic and frustrating. My experience with those O2 simulators is they can be finicky to get to work. Even if you get it to fool the ECM, for how long will it work? If it throws a MIL and she takes it to a shop for diagnosis/repair and they see that, they are going to suggest a new catalytic converter anyway.

If you "tune out" the rear O2, what about the readiness monitor for it? Does the tune set that monitor to "OK" while it ignores the rear O2? Some locals will pass a car for emissions with 1 monitor not set so you should the local you plan to register the car in.

IMO, tuning the car or fooling the car to pass emissions is best left for the owner who is willing to deal with the hassle it can present. For a person who just wants a car to work properly and have "normal" repairs, I would not do something like for them.

 

This is great information!
My exhaust has been rattling and it has been suggested that the internals of the CAT has failed.
This has put me in a position to either; replace or upgrade the Manifold w/CAT (e.g: Milltek); Or; Scab on/weld replace the CAT whist leaving the rest of the factory exhaust intact.
After reading your reply - I had contemplated upgrading my manifold header as you have but in considering, My preference would be to maintain the quietness of my exhaust and probably be looking at new or used stock replacement.

Thanks for the heads up regarding the Milltek and Hi-Flow CAT combo.

 

I think you meant/referring to @adriancl for remote tuning. (not @Adrian)

 

As for the O2 Sim, good advice for those who are not "attuned" to automotive mechanics. I ran one on my 2005 MCS "TRACKRAT" with a gutted cat on the MYNES header for many years and track events with no problems and passed state emissions every time. It's still down in Texas now, doing just fine. FWIW, A friend of mine here in W-S with a MCS just "cooked" a MILLTEK cat while attending an HPDE at VIR.

 

Interesting.
Having never owned a "modern car" - I'm obviously not as adept in knowing a lot about CATs and emission. I do have a novice understanding with regards to the internal core of a catalytic converter but - Are you suggesting or saying that a gutted CAT may still pass emissions?
Or if so - would need to be tuned out (post oxegen sensor)?
Forgive my ignorance. I may have misunderstood your statement.
Thanks.

 

A gutted Cat, by itself, will not pass emissions but, with a post Cat O2 Sim, the system thinks that all's well. Nevertheless, keep in mind the sage advice of ghostwrench.

 

How does your emission test work?

Here in The Netherlands they stick sensors in your tailpipe and they measure CO, CO2, HC and O2.
You can code the EML off but you will still fail the test without a cat.

I do understand the second O2 sensor is just there to verify the cat is working and thus not nessesarily needed to run your car or pass the test, if the cat is actually working.

 

Here in North Carolina, USA, only certain highly populated counties require testing for emissions and it's all done via the OBDII interface with a computer at the testing station corresponding to NCDOT in Raleigh, the state capitol. At present, only vehicles produced from 1999 and above must comply if they live in those counties affected. All counties require safety inspections for all licensed vehicles unless designated an "antique" and have antique vehicle registration.

 

So when I was running without a cat, a spark plug anti fowler, drilled out, worked for me. Milltek header and cat, no lights no anti fowler. I’m tuned, but didn’t have that coded out. I wanted to know if there was a problem. Hope it helps.

 

thank you. changed to the correct name

 

if your state tests by measuring your exhaust gasses from your exhaust pipe, or by visual inspection, you will fail

if they read from the obd port, and your monitors are green, you will pass

that is assuming that you either have a working cat or have coded it out, or have a simulator of some sort

 

When I first received my 04 R53 in (FL), 2003, - The best that I can recall - The initial emissions inspection involved OBDII scan, probing the tailpipe, and testing the seal on the gas cap. Over the past 21 years I've registered the Mini in three states ; Orlando,Fl, Atlanta,Ga and Austin,Tx. All that was performed during emission testing was an OBDII scan and gas cap seal test. I like things simple. That is why I would, most likely, never move back to Ca as long as I own my Mini.

Btw: Does anybody remember the good 'ol days when emission testing was only $12?

 

i remember when it was $15 bucks

whats really cool is that when you hit 25 years here you dont have to get ANY inspection. TEXAS

 

I'm running a Scorpion 4-2-1 header with cat, and no codes in the roughly 1,000 miles I've put on it.