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      11-17-2009, 04:30 PM   #67
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Quote:
Originally Posted by Singletrack View Post
At any point in time? It seems like it has to be storing some kind of history of O2 readings. Otherwise, why wouldn't the Akrapovic setup trigger the CEL immediately? Most people say it takes 50-200miles before it shows up - just as an example.

Thanks for chiming in...
Because the factory ECU software would throw a code for one of a hundred different things (constantly), BMW software engineers programed in very specific procedures for dealing with certain out of range conditions. The ECU follows these pre-programed procedures, so that it doesn't throw random fault codes when there is nothing wrong.

In other words...

The factory engine management computer is programmed with a sophisticated "false alarm" provision, to minimize the number of fault codes that would be generated by the raw data coming in. This software instructions are designed to toss out random out of parameter anomalies. (to the best of it's ability)

Otherwise, the car would be throwing codes left and right every time you started it up in the morning.

No one wants that, and the BMW engineers have designed the system to actually record (and monitor) certain conditions for a while...before it steps in and throws a code.

The ECU doesn't immediately throw a code for something like Increased emissions, because the performance of modern catalytic converters varies from the time you start the car...to the time they reach their optimum operating temperature. (to achieve their maximum catalyzing efficiency threshold)



Due to this somewhat unstable volatility, the BMW engineers have programmed in an "Intellegent Design" software monitoring system.

If the ECU receives an 02 sensor value that is out of range, it will log this unusual catalytic converter activity WITHOUT throwing a code. (initially)

After a few engine start/stop cycles, the ECU will analyze if the out of range value still exists.

If the ECU detects that this is still the case, it will trigger a fault code that is stored in the ECU's memory. The fault code can be reset (cleared) via OBD-II compliant code reading device, but it will likely return if nothing is done to change the conditions that triggered the fault code in the first place.

Until the ECU has determined that this poor catalytic converter efficiency has been rectified, it will continue to throw a code when it detects the same conditions. (after watching to see if the condition would correct itself over a short time-span)

Bottom Line: The factory ECU doesn't just step in right away to shut the party down. (for good reason)
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      11-17-2009, 04:35 PM   #68
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^^ Jesus..how do you know so much lol. Thanks for all the helpful info!
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      11-17-2009, 04:40 PM   #69
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LeMans u are a wealth of dorky and extremely detailed engineering info and i enjoy reading ur posts. the end
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      11-17-2009, 04:46 PM   #70
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Was this issue resolved? I don't really want to have CELs..
Based on your sig "Coming Soon: Powerchip & Fabspeed X-Pipe with Resonators + 200 Cell HFCs" it looks like you're going to run custom software so does it really matter?
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      11-17-2009, 05:33 PM   #71
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Thanks for the detail Lemans - that makes sense.
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      11-17-2009, 05:36 PM   #72
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Based on your sig "Coming Soon: Powerchip & Fabspeed X-Pipe with Resonators + 200 Cell HFCs" it looks like you're going to run custom software so does it really matter?
Oh dang, I need to change that I was going to go down to Houston and get on the GB for the powerchip but I couldn't make the date
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      11-17-2009, 06:46 PM   #73
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Originally Posted by Wanted_M View Post
If my memory serves me, the short/long term fuel trim CEL it's triggered by the MAF seeing a deveation from your stock air/fuel curve.
The stock ECU tries to learn and compensate the new air flow and tries to trim a certain %.

If by a certain time the correction factor is not brought back to the desired curve or %, it will trigger a CEL which means tuning (including the re-scaling of your MAF), going back to a stock cat or installing a spacer on the rear O2 sensor.

On my last car, I installed a spacer on the rear O2 sensor (due to no cats) and it worked, no more CEL.

Question to Fabspeed;
If we decide to turn off the rear O2 sensor, will CA cars dispaly a "READY" or "NOT READY STATUS"?

Thanks
I'm going to jump in and give answers to both questions, since I had spacers installed for the past month.

1. Spacers DO NOT work on this car, after a thousand miles with them installed, the same codes came back.

2. Turning off the rear O2s will give you a NOT READY status, by turning them off, it will result in 2 or 3 readiness test failure as shown on any OBD II scanner. I'd learned that from my other cars.
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      11-17-2009, 10:25 PM   #74
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I wasn't able to get my friend's general purpose software working. We believe the issue was the cable in question. In any event, I dropped by Autozone and used their tool.

There were three codes:

P0430 - catalyst system efficiency below threshold bank 2
P0430 - catalyst system efficiency below threshold bank 2
P0420 - catalyst system efficiency below threshold bank 1

I cleared all three codes and the SES light went out. I checked and I had 1750 miles on the car since the exhaust was installed. I'm getting 14.5mpg in that time - hahahaha; ouch fuel bill. I've been driving it harder since getting the exhaust ; )
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      11-18-2009, 01:02 AM   #75
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Quote:
Originally Posted by Lemans_Blue_M View Post
Because the factory ECU software would throw a code for one of a hundred different things (constantly), BMW software engineers programed in very specific procedures for dealing with certain out of range conditions. The ECU follows these pre-programed procedures, so that it doesn't throw random fault codes when there is nothing wrong.

In other words...

The factory engine management computer is programmed with a sophisticated "false alarm" provision, to minimize the number of fault codes that would be generated by the raw data coming in. This software instructions are designed to toss out random out of parameter anomalies. (to the best of it's ability)

Otherwise, the car would be throwing codes left and right every time you started it up in the morning.

No one wants that, and the BMW engineers have designed the system to actually record (and monitor) certain conditions for a while...before it steps in and throws a code.

The ECU doesn't immediately throw a code for something like Increased emissions, because the performance of modern catalytic converters varies from the time you start the car...to the time they reach their optimum operating temperature. (to achieve their maximum catalyzing efficiency threshold)



Due to this somewhat unstable volatility, the BMW engineers have programmed in an "Intellegent Design" software monitoring system.

If the ECU receives an 02 sensor value that is out of range, it will log this unusual catalytic converter activity WITHOUT throwing a code. (initially)

After a few engine start/stop cycles, the ECU will analyze if the out of range value still exists.

If the ECU detects that this is still the case, it will trigger a fault code that is stored in the ECU's memory. The fault code can be reset (cleared) via OBD-II compliant code reading device, but it will likely return if nothing is done to change the conditions that triggered the fault code in the first place.

Until the ECU has determined that this poor catalytic converter efficiency has been rectified, it will continue to throw a code when it detects the same conditions. (after watching to see if the condition would correct itself over a short time-span)

Bottom Line: The factory ECU doesn't just step in right away to shut the party down. (for good reason)
Wow! Why don't you spell it out in "lay terms" brother!

My questions:

What is the long term risk of de-activating the rear O2 Sensors from a Dyno tune and "Not knowing" what is going on?

What is the likelihood of throwing a code with Fabspeed X-Pipe and only Secondary delete?

Thanks BMW Yoda!
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      11-18-2009, 11:23 AM   #76
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Quote:
Originally Posted by SoCalM3Mang View Post
My questions:

What is the long term risk of de-activating the rear O2 Sensors from a Dyno tune and "Not knowing" what is going on?

What is the likelihood of throwing a code with Fabspeed X-Pipe and only Secondary delete?
1) No long term risks, except for failed state emissions tests. (most guys just pay someone off when their inspection comes around)

Your car will end up running a little 'rich' (for safety purposes), since the ECU is no longer receiving the accurate post-cat 02 sensor data it needs.

That data is required to properly adjust the intake air (throttle body butterflies), fuel trim (fuel injector duty-cycle), and spark. (individual coil packs)

2) It won't make any difference whether or not you have a second set of cats or not. Your chances of getting a CEL due to increased emissions is still the same.

All of these aftermarket x-pipes are a crap shoot. You just have to live with the occasional fault code...or just keep your stock setup.

The primary OE catalytic converters on the E90/92/93 M3's are made with a Ceramic Brick core (substrate) material that has 400 cells per square inch.

Most of the aftermarket catalytic converters on the market use a Metal Matrix (spiral wound wire mesh) core material. This type of catalytic converter is LESS effective at filtering out exhaust gas impurities. In addition to this, most aftermarket x-pipe manufacturers use 100 cpi or 200 cpi hi-flow cats that have a higher CFM (cubic feet of air per minute)rating than our stock 400 cpi cats.

That increased cfm rating is the root cause of this particular problem...

The "Increased Emissions" codes that are triggered as a result of an x-pipe swap (P0420 Bank 1 & P0430 Bank 2), are triggered because the velocity of the exhaust gas flow (passing through the these aftermarket catalytic converters) has increased substantially over the performance of the OE cats.

The 100 cpi and 200 cpi aftermarket cats cannot remove enough C0 from the exhaust gas stream, before it exits out the other side. (where the post-cat 02 sensors are located)

The post cat 02 sensors are detecting this catalyst ineffeciency...and it throws the two fault codes listed above.
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      11-18-2009, 11:33 AM   #77
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Quote:
Originally Posted by Lemans_Blue_M View Post
1) No long term risks, except for failed state emissions tests. (most guys just pay someone off when their inspection comes around)

Your car will end up running a little 'rich' (for safety purposes), since the ECU is no longer receiving the accurate post-cat 02 sensor data it needs.

That data is required to properly adjust the intake air (throttle body butterflies), fuel trim (fuel injector duty-cycle), and spark. (individual coil packs)

2) It won't make any difference whether or not you have a second set of cats or not. Your chances of getting a CEL due to increased emissions is still the same.

All of these aftermarket x-pipes are a crap shoot. You just have to live with the occasional fault code...or just keep your stock setup.

The primary OE catalytic converters on the E90/92/93 M3's are made with a Ceramic Brick core (substrate) material that has 400 cells per square inch.

Most of the aftermarket catalytic converters on the market use a Metal Matrix (spiral wound wire mesh) core material. This type of catalytic converter is LESS effective at filtering out exhaust gas impurities. In addition to this, most aftermarket x-pipe manufacturers use 100 cpi or 200 cpi hi-flow cats that have a higher CFM (cubic feet of air per minute)rating than our stock 400 cpi cats.

That increased cfm rating is the root cause of this particular problem...

The "Increased Emissions" codes that are triggered as a result of an x-pipe swap (P0420 Bank 1 & P0430 Bank 2), are triggered because the velocity of the exhaust gas flow (passing through the these aftermarket catalytic converters) has increased substantially over the performance of the OE cats.

The 100 cpi and 200 cpi aftermarket cats cannot remove enough C02 from the exhaust gas stream, before it exits out the other side. (where the post-cat 02 sensors are located)

The post cat 02 sensors are detecting this catalyst ineffeciency...and it throws the two fault codes listed above.
As far as I know Cats do not remove CO2 from your exhaust, they create CO2, Water, and Nitrogen by converting carbon monoxide, nitrous oxide and unburnt fuels.
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      11-18-2009, 12:15 PM   #78
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As far as I know Cats do not remove CO2 from your exhaust, they create CO2, Water, and Nitrogen by converting carbon monoxide, nitrous oxide and unburnt fuels.
Your right... I always end up calling carbon monoxide C02 when the correct abbreviation is just C0.

Thanks.
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      11-18-2009, 01:00 PM   #79
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It is my understanding that the primary O2 readings are used in determining the fuel trim and other parameters. Turning off the rear O2 has zero effect on the stochiometric or whether you run rich or not. It is only for OBDII compliance.

I have heard from reliable sources that the M3 primary cat may be higher than 400 cpi density. Is your data confirmed??

Thanks!

Quote:
Originally Posted by Lemans_Blue_M View Post
Your car will end up running a little 'rich' (for safety purposes), since the ECU is no longer receiving the accurate post-cat 02 sensor data it needs.

That data is required to properly adjust the intake air (throttle body butterflies), fuel trim (fuel injector duty-cycle), and spark. (individual coil packs)

The primary OE catalytic converters on the E90/92/93 M3's are made with a Ceramic Brick core (substrate) material that has 400 cells per square inch.
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      11-18-2009, 01:11 PM   #80
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It is my understanding that the primary O2 readings are used in determining the fuel trim and other parameters. Turning off the rear O2 has zero effect on the stochiometric or whether you run rich or not. It is only for OBDII compliance.
I'm with you on this one.
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      11-18-2009, 02:29 PM   #81
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It is my understanding that the primary O2 readings are used in determining the fuel trim and other parameters. Turning off the rear O2 has zero effect on the stochiometric or whether you run rich or not. It is only for OBDII compliance.

I have heard from reliable sources that the M3 primary cat may be higher than 400 cpi density. Is your data confirmed??

Thanks!
Quote:
Originally Posted by J08M3 View Post
I'm with you on this one.
The factory ECU uses 4 Bosch oxygen sensors to monitor the exhaust gas stream at all times. (in your typical unmodified stock M3)

The ECU uses this real-time 02 sensor data to control the fuel injection system and ignition timing.

The 2 oxygen sensors mounted upstream of the catalytic converter, tells the ECU how much oxygen is in the exhaust. The ECU can increase or decrease the amount of oxygen in the exhaust by adjusting the air-to-fuel ratio.

The 2 oxygen sensors mounted downstream of the catalytic converters monitor the efficiency of the cats to reduce the harmful emissions produced by the internal combustion process.

This control scheme allows the ECU to make sure that the engine is running as to close it's ideal AFR's regardless of the operating conditions.

The 4 oxygen sensors (working together) insure there is enough oxygen in the exhaust gas flow to allow the oxidization catalyst to burn the unburned fuel, VOC's and CO at peak efficiency.

I see that many of you seem to think the post-cat 02 sensors don't really DO anything really...

Well that's not true.

Every automobile manufacturer uses the rear 02 sensors to fine tune the fuel trim.

The post cat 02 sensor functions as a fuel control input.

This sensor is used to fine-tune the air-fuel ratio to maximize catalyst efficiency in normal (and abnormal) driving conditions.

The ECU can also adjust the air-fuel ratio to compensate for a degraded catalyst. (within a fixed pre-programed range)

If you were to measure the actual amount of time the post-cat 02 is used during the running of the catalyst monitor (maybe once per trip), and compare that to the amount of time the post-cat 02 is used fine tune the air-fuel ratio (almost always in closed loop), you will see that this sensors plays a major function in the overall fuel control of your internal combustion engine.

Every vehicle manufacturer today uses the post-cat 02 for fuel correction.

Our factory ECU's job, is to process the incoming data stream from all four 02 sensors, and make the necessary (air,fuel, and spark) adjustments based on the conditions at hand.

The ECU's responsibility is to keep the oxygen sensors within a preset range (typically between 0.1 volts and 1.0 volts) for optimum fuel efficiency, lowest carbon emissions, and the best fuel economy.
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      11-18-2009, 02:38 PM   #82
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Lemans,

I'm not disagreeing with you at all. But I question if the rear O2 sensor is controlling fuel as well how come those with a CEL due to HFCs aren't running any worse than those who don't have a CEL?
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      11-18-2009, 03:57 PM   #83
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Lemans,

I'm not disagreeing with you at all. But I question if the rear O2 sensor is controlling fuel as well how come those with a CEL due to HFCs aren't running any worse than those who don't have a CEL?
They are running a little worse...they just don't realize it.

The post cat 02 sensors are simply used to fine tune the AFR's, not directly control them. That job is reserved for the pre-cat 02 sensors.

Here is where confusion comes in...

Many BMW owners think the post-cat 02 sensors don't play a role at all, because once they are turned off...they can't tell the difference with their "butt dyno".

A word to the wise...

Butt dynos are notoriously unreliable. lol...

When you tell them the post-cat sensors actually do play a role in the ECU tuning they can believe it because if it did...they would FEEL the difference in power.

Well here's why they don't...

The pre-cat 02 sensor data controls about 99% of the overall ECU tuning functionality.

The post-cat 02 sensors control approx. 1% of the ECU tuning functionality.

That's WHY the majority of the guys who shut off the post-cat 02 sensors think they don't have any effect.

1% of 414hp is...4.1 hp.

4.1 flywheel hp = approx. 3 rwhp
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      11-18-2009, 04:02 PM   #84
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Butt dynos are notoriously unreliable. lol...

1% of 414hp is...4.1 hp.

4.1 flywheel hp = approx. 3 rwhp
Couldn't agree more on the butt dyno comment. Hence all the fun I poke at people that claim their new air filter or under drive pulley are must haves cause they make their car faster.

Interesting on the post cat O2 sensor though, I didn't know that.
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      11-18-2009, 04:25 PM   #85
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1% of 414hp is...4.1 hp.

4.1 flywheel hp = approx. 3 rwhp
Ok, well that makes me feel better at least : )

FYI to those following the thread, I PMed Julius @ WSTO since that is who I bought the Fabspeed through to see what he/Fabspeed would like to do. I'll keep the forum posted...

Unfortunately, I think I may have a leak at one of the welds on the "X" also. I need to get back under the car and check, but when I installed my rear slip-on, I noticed water dripping from the X and exhaust stains as well : (
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      11-18-2009, 05:21 PM   #86
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Quote:
Originally Posted by Lemans_Blue_M View Post
1) No long term risks, except for failed state emissions tests. (most guys just pay someone off when their inspection comes around)

Your car will end up running a little 'rich' (for safety purposes), since the ECU is no longer receiving the accurate post-cat 02 sensor data it needs.

That data is required to properly adjust the intake air (throttle body butterflies), fuel trim (fuel injector duty-cycle), and spark. (individual coil packs)

2) It won't make any difference whether or not you have a second set of cats or not. Your chances of getting a CEL due to increased emissions is still the same.

All of these aftermarket x-pipes are a crap shoot. You just have to live with the occasional fault code...or just keep your stock setup.

The primary OE catalytic converters on the E90/92/93 M3's are made with a Ceramic Brick core (substrate) material that has 400 cells per square inch.

Most of the aftermarket catalytic converters on the market use a Metal Matrix (spiral wound wire mesh) core material. This type of catalytic converter is LESS effective at filtering out exhaust gas impurities. In addition to this, most aftermarket x-pipe manufacturers use 100 cpi or 200 cpi hi-flow cats that have a higher CFM (cubic feet of air per minute)rating than our stock 400 cpi cats.

That increased cfm rating is the root cause of this particular problem...

The "Increased Emissions" codes that are triggered as a result of an x-pipe swap (P0420 Bank 1 & P0430 Bank 2), are triggered because the velocity of the exhaust gas flow (passing through the these aftermarket catalytic converters) has increased substantially over the performance of the OE cats.

The 100 cpi and 200 cpi aftermarket cats cannot remove enough C0 from the exhaust gas stream, before it exits out the other side. (where the post-cat 02 sensors are located)

The post cat 02 sensors are detecting this catalyst ineffeciency...and it throws the two fault codes listed above.
Assuming I understand anything you and JM803 are talking about the natural question:

Why isn't the tuning community/aftermarket folks making HFC's 400cpi or better?

Is it possible to make them at this level and still make them "High Flow"?

Thanks.
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      11-18-2009, 05:32 PM   #87
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Assuming I understand anything you and JM803 are talking about the natural question:

Why isn't the tuning community/aftermarket folks making HFC's 400cpi or better?

Is it possible to make them at this level and still make them "High Flow"?

Thanks.
More cpi ~ less CFM

CFM backwards is M-F-C. Medium-flow cats.
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      11-18-2009, 07:00 PM   #88
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Lemans,
Do you know of any tuning company that has the ability to turn off the monitoring function on the post-cat sensors? Like turn it half off if you know what I mean.
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