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Discussion Starter · #1 ·
Even after all these years, I still get a silly grin on my face every time I walk up to my M3, so I just can't part with it. However, it's failing smog :-( I replaced the O2 sensors, but no difference, so it must be the cats.

Any advice? Does anyone have stock cats for sale? :)
 

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Post your results up for review along with any DTC codes, Freeze Frame info and warm idle and steady highway cruise Fuel Trims.
 

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Discussion Starter · #3 · (Edited)
Sure:
Fail #1: not available
Fail #2: Here
Fail #3: Here
Fail #4: Here
Another Manual Test: Here

Throwing code P0430. How can I get the other info you asked about? I do have an ODBII reader and DashCommander, so I think the data is available. Thanks for taking a look!
 

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Test #2 shows you at 15% CO2, which means the cats are working just fine. Test #3 and #4 look like the cats aren't warmed up yet. You say O2 sensors have been replaced. Why? Judging by the data, I would give an educated guess that one or both front O2 sensors are sluggish. Full rich/lean swing needs to be under 100 milliseconds at worst. ~80ms or less is what you are looking for. You need a DSO to test them properly.
 

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Discussion Starter · #5 ·
How can I do a DSO test? It seems that the DashCommander doesn't read fast enough, as there are always pauses in the O2 sensor voltage reading.
 

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DSO: digital storage oscilloscope. When nit-picking a smog failure, you need equipment. Guessing will only throw money away. Having a dyno to re-run against your baseline helps too.
 

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Discussion Starter · #7 ·
Where do I hook up the multimeter? What's the procedure to test it? Too bad ODBII isn't fast enough :-(

Just got the quote from GMS for $5476 for the cats; man, I really hope you're right!
 

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Testing air/fuel sensors is outside of the scope of a post here. To start: http://bit.ly/1qNCEf5 I hate to just say take it to a shop, but this is one of those problems that a well seasoned test and repair station can help with. Anyone trying to sell you cats off of the bat didn't test anything properly.
 

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Discussion Starter · #9 ·
Thanks for the info.

Does anyone have a recommendation for a shop in San Jose, CA? I tried going the Yelp route, and found someone who was really friendly but not technical enough to figure out the problem (he was test-only).
 

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No need for any DSO testing here, you just need to finger print your O2 sensors from cold start using an OBDII tool that can record the data stream/PID's for the O2 sensors then graph them out. I can tell you very quickly what shape the O2 sensors are in an you never need to open your hood.

First thing you need to do is make absolutely sure the engine is running warm enough. I see soft failed thermostats all the time and the engine could be running too cold. Not sure about the M3 for sure, but I expect it should run consistently around 90C?? Maybe some others can chime in one where their cars temps are running.

For the non M cars, see the 3rd link in my signature for the issues, they are the same, just need to know what a good M3 temp should be.

As for the O2 sensors, see this thread for an idea of how to PROPERLY test them.

http://forum.e46fanatics.com/showthread.php?p=16203126

You can also do this with the Post Cat sensors as well, however, do not often have to do this for the post Cat sensors.

I have not even had a time to review the results you posted so I need to go over them a bit more, but I would still like to know what the Fuel Trim values are.
 

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I am guessing the thermostat is soft and you may have some lazy O2 sensors.

The M cars get rich very quickly when the engine temps drop.

Initially I am thinking this should be a pretty easy situation to resolve.

The P0430 codes you should be able to work around as these can be nuisance codes and simple things like exhaust or O2 sensor bung leaks can also cause these during decel.
 

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Discussion Starter · #12 ·
I took some samples, which will hopefully include the O2 sensor.

Does anyone have the Palmer Dashcommand software for their PC? If so, could you convert these lgf files to csv? They don't seem to have a Mac version.

Data Sample #1: file1.lgf
Data Sample #2: file2.lgf
Data Sample #3: file3.lgf
 

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Not so impressed with Dash Command.

Depending on your phone platform, get either Touch Scan or Torque Pro for Android or OBDFusion for iProducts.

Less than $10 and will output directly in a .csv file format.

If $10 helps you solve the issue you are all set.

Also what is the engine temperature running?

See 4th link in my signature for the Hidden OBC menu and/or use your App.

Also run the car on the highway at night and see how low the temp drops.

The thermostat is a 80C stat, but beware this does not mean the engine runs at 80C, the engine will most likely run at closer to 90C due to where the coolant temp sensor is located.
 

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Discussion Starter · #14 ·
Ok, I took a Diagnostic Report with ODB Fusion while driving home tonight:
Report Here
Will need to spend some more time with the app, to figure out how to gather data in csv.
 

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The report is somewhat helpful, engine temp looks close to correct, but you may have to search around and find out what a M3 with a new thermostat engine temp runs at. I think it may be a bit higher, closer to 90C but I could be wrong.

As for .csv data, I think the tool already stored the data that way? I do not personally have OBDFusion, but support many that have it and they have no issues getting .csv data from the tool.

As for the diagnostic report, the one Fail listed under $06 is for on board monitoring and something failed. These items are hard to identify and often if you focus on other areas of the vehicle you can resolve these issues.
 

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Not in CA.
 

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OP: I've run 1000's of vehicles on a dyno and 5 gas analyzer, from '74 clunkers to 599GTBs. Engine temp, unless wildly out of spec doesn't affect much but NOx on non-EGR engines, because the engine is maintaining fuel control immediately upon closed loop. The air/fuel sensors are at operating temp in seconds; cats in a minute or so. Your CO measurements are saying that being rich (partially burnt fuel) isn't an issue. HC (unburnt fuel) is within a few PPM of passing. When splitting hairs, it makes sense to manually test components with diagnostic equipment to check their actual performance. Good luck!
 

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The M cars are mapped very differently than the standard non M cars.

While I do not own an E46 M3, I do own a E39 M5.

I can assure you without question the E39 M5 will run extremely rich when the engine temperature drops at low as only 4 degrees C below the "nominal" operating point. And this is still in closed loop, these small differences in engine temp do not have any impact on close loop operation typically.

Thermostats typically go soft in as little as 2 years, so I start with the basics, especially with the M cars and make sure the engines are in fact running at their "nominal" operating temperature.

While still in closed loop, many modern cars are operating in closed loop in a few as 90 to 120 seconds. But engine coolant temperature does not impact the close loop status, it switches to a richer fuel mapping.

The M5 will have black, wet tail pipes, soot all over the rear bumper and license plate and generally run a bit below expected performance when the engine operating temp is only off by as little as 3-4 C from its baseline.

I would expect the M3 to behave very similarly as well. Also do not fall into the trap that the nominal engine temperature is the thermostat operation temperature, it is not. In general the nominal engine operating temperature is 10-15F/5-8C above the thermostat operating temperature.

Do what you want, but I have found that more often than not the basics are overlooked and missed. With the cost of a thermostat, it makes sense to start there in my opinion.
 

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You can check the OBC read out for engine temps using the gauge cluster trick. Use that to make sure your engine is reaching optimal temp before throwing money at anything.
 
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