this is about getting kmickeys car fixed. At least how I read it.

Matt

 

Thats cool, started a new thread for my ranting Feel free to post, or not.

 

Here we go.........the CAT is only as good as the gasses fed into it.....a good CAT cannot clean the exhaust from an overly rich or lean running engine...even if the CAT is stock and brand new.

I would suggest the following: observe the front o2 sensor on an OBD scan tool capable of reading data stream.

The sensor must go high (.8vdc) and low (.2vdc) on a regular basis at idle. If your front sensor is switching regular then the ECM has fuel control.

The next thing to look for is: observe the Short Term Fuel Trim at idle. It too will switch high to low as this is the signal that is driving the o2 sensor; make sure it does not exceed 8% peak to peak as this is an indication of a lazy sensor that will allow the feed gasses into the CAT to exceed the capability of the CAT resulting in pollution.

Next take the car for a run and have an assistant observe the front o2 sensor and LTFT while you drive at WOT! Be careful you do not have to be going fast for this step; you could be climbing a hill @WOT. You are looking for the front o2 to go to .8 or more and remain there for the entire WOT run. This is an indication that there is no fuel starvation; also the LTFT should not jump that much if at all, again indicating that the fuel system is able to deliver.


The reason the o2 sensors of the front switch back and fourth is by design!
The CAT will store oxygen during the lean cycles (and consume said oxygen to burn residual HC in the exhaust to convert CO and HC into CO2 and H2O)
During the rich cycle the temperature of the exhaust is reduced to combat the formation of NOX) Nitrogen burns at 2500F to form NOX. So the front o2 must constantly switch high to low and back or the CAT will not be able to do it's job due to the feed gasses are out of range (garbage in garbage out).

So take the time to understand what you are feeding you CAT before you replace anything. Good luck and I hope this helps!
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Which OBD scan tool capable of reading data stream would you recommend?

Folks, I really appreciate any and all of your help.

kmickey

 

There are several on the market, one that has graphing capabilities. I use the AutoEnginuity because it is a full featured tool, is laptop based and has unlimited graphing/recording (depending on hard drive space)

 

I've got it and live in Woodside if you want to use it for a bit....

Also got BiM-COM beta, it will do it too. BimCom has faster update speeds too.

Matt

 

Mickey, please do share as you learn more... I hope you can get this figured-out soon without too much heartback and expense.

 

Do you have an aftermarket tune? Didn't catch this reading through the thread.

If so, don't they tend to run much leaner than stock? While I love my RMW tune, I do wonder what will happen when it comes time to get smogged...

 

As long as the emisions are good, no problem. There is no way for them to "see" certain things, such as a cam, a BV head or a tune, they just will not open up your engine to check and will have no need to check the ECU for what tune you have.

 

There have been cars with Jans tunes that have passed smog. The leaning of the mixture isn't really at light load (like what is tested) but more on WOT.

Matt

 

That makes sense, thanks.

 

http://www.car-sound.com/04basics/04california.asp

Just thought you might wanna know.

The Pre-cat on the stock header is a NOX trap.

 

Ah ha. Have we found the proverbial smoking gun?

 

When I read that, I thought the same thing. But, don't pretty much all aftermkt headers do without a precat? I'm guessing by now a fair number of MINI's have gone through a smog test in CA and if this was the culprit, there would be more such threads. Ah, maybe not... I hope you were able to meet with Matt to do some data capturing.

 

I think your first smog test in CA is 6 years after purchase (or if ownership changes), so original owner 03s are just starting to hit now. Probably not that many modified 02s out there. My 04 is up next year...

 

Strange thing is that I got my MINI several weeks before Mickey, yet my DMV renewal didn't request a smog test. That is why above I thought (actually Mickey) that it could be a county thing...

 

and pure spirit!

And not that many modded 02s? I think actually that most of the 02s were modded to some degree or another. The earlier in the market cycle, the nuttier the buyer!

Matt

 

I was on the MINI waitlist a year before the US release. I could have received an MCS a year before I actually did, but I wanted IB, and that color was only available in the Cooper the first year of production. So, I gave-up my spot many times in order to get the first build '03 build week, waiting an additional year...

A year plus of MCS sales in CA prior to my purchase should make for a decent number of smog tests by now.

I was just reading on another forum about Militek cats not lasting all that long, especially in higher output applications.

As Matt said earlier, and me in PM before this thread, while tunes tend to lean-out our pig rich mixtures, that might not be the case in the lower ranges, such as seen during this analysis. Maybe a re-focus there could be beneficial...

This brings-up a question, Mickey's test included:

1338ppm at 15mph.
1258ppm at 25mph.

Same gear, 1st?

Were there other tests, or are these just the ones where failure happened?

I know when I get a tune, I'll ask for some cleaning-up in these areas...

 

So what about the pre-cat NOx trap theory?

 

indirectly I'd heard that the "pre-cat" was to keep start up emissions lower at very cold temps. But this is indirect info so I don't know for sure. I do know that cars without the pre-cat and good aftermarket cats have passed smog though.... If the NOx trap were really needed, they wouldn't have passed.

Also, there are lots of cars that get very low emissions levels without NOx trap technology.

Matt

 

Heard the same too Matt... I figured that I'd have my car plenty warm prior to testing. Can someone confirm the testing speeds for this test?

 

Ok, I'll answer my own question. Just confirmed it:

"The new test actually is an easier one for older vehicles as most are no longer tested while at idle. Vehicles are tested under load in a simulated driving test at 15 & 25 mph."

Again, with any tuning, I'd put some focus there also...

 

I have a June 2002 S. I moved to CA in June of last year from VA. I was severely stressed over the CA smog test and went back to Stock Intercooler and CAI. I was already on my second header by then (alta) but car passed no problem

 

Matt,
I would like to take you up on your offer. I can trailer my car to your place.

I have not had the car "re-tested" yet.
This is what I have done so far:

Before 1st smog test:
Replaced post-cat O2 sensor. The car was throwing a PO420 code.
Replaced Alta CAI with factory air cleaner. Original filter with about six months of use before CAI was installed.
I had about a half take of 91 octane.
Test drove the car about twenty miles. Did not throw PO420 code.
Spark plugs (Denso) were replaced <6 months ago, or about 2k miles on them.
Last oil change: End of November (2008).

1st Smog test January 24, 2008:
Drove the car downtown <7 miles to smog station.
Then the car sat for about ten to fifteen minutes. Then the Smog Tech drove the car up on the 15/25 mph smog dyno. The test took about 10 minutes or so to complete/fail NOx.

Installed new JCW 380cc injectors.
Installed new OEM air filter.
Test drove about 5 miles, no codes.
Installed new plugs: Brisk. Now idle is a little rough and seems sluggish.
Test drove the car to Sunol gas station (about 8 miles) to fill up with high octane. They have 93, 96, 98 and 100 unleaded octane and 110 leaded.
On the way there, I got a dreaded PO420 code.
My code reader is crapping out on me. It displays "Error" and I'm not able to clear it at this time.

Mickey

 

Wow, this sounds like a real nightmare. Hope you get things sorted out.