Questions on X-Pipes??

[MMMorish]

Originally Posted by BimmerRob08

Depending on a few factors that may or may not work for you personnely, you can do this. Go with a HFC x-pipe, sport or race exhaust as you like. If you do get a CEL, reset it with a CANBUS code reader. If it comes back hundreds of miles later it's just a plug, read & erase and off you go. If smog test is an issue, then make sure you didn't discard the stock x-pipe & CAT's and you'll have to reenstall them. It would be kinda of a pain in the ass, especially if you don't have a lift but my reasoning is all year round I can drive with the HFC & X-pipe, if it passes smog/emissions then great, if not, I can reenstall it and it's something I'd have to deal with once a year but hell, I don't mind working on cars. Just depends on what works for you. But probebly expect a CEL. Mine came of after just 600+ miles with the Encore system. Shit happens I guess. Good luck.

Living in Ontario, Canada, we have to do a "Drive Clean" emissions test every two years. Not sure how that compares to smog tests in the States.

I do have my own lift, but not sure if I want to be changing out pipes every two years. I'm the "set it and forget it" type of guy. Don't get me wrong, I love working on my cars as well, just don't want the added hassle.

[powertrip]

I'm running virtually the same set-up. You actually will not have much drone at all with this set-up. The only time I have experienced drone is climbing a grade in 7th gear at 3k rpm's. Cruising on the freeway at 3k is surprisingly quiet .

[MMMorish]

Originally Posted by powertrip

I'm running virtually the same set-up. You actually will not have much drone at all with this set-up. The only time I have experienced drone is climbing a grade in 7th gear at 3k rpm's. Cruising on the freeway at 3k is surprisingly quiet .

Your sig says that you've done HFC's and I also remember you once mentioning in another thread that you wanted to swap out your exhaust because it was too loud. Did you end up swapping out your AP exhaust or did you keep it? Is it only loud at WOT?

[powertrip]

Yeah, I'm still running the AP. It's really loud when you're on the throttle, but not bad at all when you're cruising. I think you'll be happy with the sound.

Originally Posted by MMMorish

Your sig says that you've done HFC's and I also remember you once mentioning in another thread that you wanted to swap out your exhaust because it was too loud. Did you end up swapping out your AP exhaust or did you keep it? Is it only loud at WOT?

[///FCB]

if you do get a cell, what sort of tune do you require? simply delete the error message or something more??

[MMMorish]

Originally Posted by powertrip

Yeah, I'm still running the AP. It's really loud when you're on the throttle, but not bad at all when you're cruising. I think you'll be happy with the sound.

Okay good. With so many exhausts on the market, the two main concerns for me were sound/tone and build quality and I liked the AP the best. Not really looking for gains out of an axle back.

[BimmerRob08]

Originally Posted by ///FCB

if you do get a cell, what sort of tune do you require? simply delete the error message or something more??

From what other's say, you can either invest about $<100 for a code reader and just reset it or pay $$$$ for a tune and risk voiding the warrenty, unless it's a Dinan tune. That should take care of the CEL's comming on when ever. I won't be living in California when I get this M3 back to the States but if there is a visual inspection like in Cali (I think), then you would have to go back to stock to pass. Don't know what every one else in Cali is doing. I'll admit, it's a pain to have to change it out every year or two. I'm wondering if I want the hassle too. But I just spent $1800 on it, so don't want to waste the money and sell it off or store it in my garage for nothing. Just depends on what you are willing to do.

[H Bomb]

do you have to have cats where you live?? if not i highly suggest the Dinan Midpipe. it is civil and only loud when you want it to be. there is no drone. you do need there midpipe software though

not sure what muffler you have coming but when paired with the dinan rear it is one of the best systems i have ever heard on any car for that matter and is powerful and doesn't drone and doesn't throw any codes. i don't really know what else one could ask for in a system.

Originally Posted by MMMorish

I have an exhaust coming and I'm thinking about doing the x-pipe as well. Looking into the Fabspeed with resonators (want to keep it civil). My questions are:

1. Without a tune, will it cause a CEL to come on?

2. Will it increase the amount of drone in the cabin?

3. Will it be a lot louder?

Thanks for your help.

Nick

[Lemans_Blue_M]

Originally Posted by alpina527

That's good info. Could you explain one more thing though.

On most aftermarket x pipes such as the Akra Evo, the old primary cat Lambda sensors both fit in front of the HFC which is a few feet further down stream.

This means there will be no difference at all between the readings on both probes.

Who doesn't the second probe go behind the HFC with an extension wire or similar? Surely this would help with the CEL if software isn't changed.

Well, you need to understand something first...

The design of an Akrapovic Evolution exhaust system is more about performance, and less about avoiding a CEL.

The position of their 100-cell metal-matrix (or optional 200-cell metal matrix) cats a few feet farther downstream, is to extract more horsepower & torque from the mid-pipe section.

By placing them that far away from the exhaust header flange, the exhaust gases are not restricted in any way. (until they encounter the HFC's farther back). This allows the engine to expel the exhaust gases out the cylinders in a more efficient manner. The closer the cats are to the exhaust ports, the more back pressure (restriction) you will have in the exhaust system.

Akrapovic's evo exhaust is a free flowing design concept, that is attempting to reduce that back pressure, and as a result, it's frees up a lot of HP & TRQ. (by improving the efficiency of the entire exhaust system)

Unfortunately, "free-flowing" and "emissions legal" are two different things.

The Akrapovic design will always throw an emissions related CEL, because of the the location of those HFC's.

Even if you cut out the Akrapovic 100-cell (or 200-cell) HFC's, and replaced them with our factory OEM 400-cell ceramic cats...it would still throw a CEL.

Why?

Because catalytic converters need to be heated up to function properly, and any cats (aftermarket or OEM) have exactly zero chance of functioning properly that far down in the exhaust stream.

So the only chance you have of NOT throwing a C.E.L., is to find the perfect (or nearly perfect) set of 200 or 300 cell HFC's, and place them exactly where the OEM cats are located. (and hope for the best)

That's as good as it's going to get folks.

Note: Not every 200-cell or 300-cell HFC is going to have the same CFM flow rate, so you can't just say: "My cats are 200-cell, so therefore..."

It's not that simple...

The physical length, width, height, internal catalyst materials used, the wash coat, and the arrangement of the cells, all make a difference. There are hundreds of different aftermarket high-flow cats on the market, and the only way to find out how they work on a particular car, is to test them. One at a time...

And even if you do find a the right one, you'll still be right on the edge of throwing a check engine light.

It's important to know (on a basic level) what the ECU is actually looking for, so you can understand why you get a check engine light in the first place. (under certain circumstances)

So here's a crash course on how this all works...

The factory ECU is simply monitoring the 2 pre-cat & 2 post-cat oxygen sensors for any abnormal readings in the switching voltage differential.

Now if the switching voltage differential between the pre-cat and post cat O2 senors on the left or right bank of the exhaust system is too great, the ECU will log this event into memory.(if the post cat sensor reading are the problem)

Now if the ECU detects a switching voltage problem (that is outside the normal range) for a pre-cat sensor, then the ECU will immediately throw a CEL, since the pre-cat sensor data is required to make normal adjustments to the fuel air mixture. (there is an emergency "back up map" stored in the ECU, but it is only used in extreme situations)

So when you replace the cats with high flow versions, or you remove them from the exhaust stream entirely, you are changing the switching voltages on the post-cat O2 sensors. to a level that is outside the acceptable limit. (on the left or right exhaust bank)

The only thing an aftermarket software provider can do (legally), is to alter the software so it doesn't trigger CEL on the dash. That's it.

Anything more invasive would land them in serious hot water with the environmental agency in that particular country. (none of the BMW aftermarket tuners want to tempt fate in that regard)

[alpina527]

Thanks for the excellent explanation. I already had a basic understanding, but you have cleared up all the important bits.

[BimmerRob08]

Thanks for explaining. So that brings up a question. If now I have HFC with my X-pipe. stock ECU software and even before it through a CEL or after I clear it. Let's say a few thousand miles go by with no CEL. is my engine then not running at it's optimum fuel/air mixture because the pre & post O2 sensors are sensing something different than stock perameters? Or will the mixture be incorrect causing other problems down the road only if the CEL comes on as then the ECU detected a problem?

I wonder if over time, is it going to cause problems on fouling the plugs, cylinder's, etc? I think I'm already noticing a slightly higher fuel consumption of about .5 to .8 mpg since the light came on and I'm not driving it any different than before. Thanks,

[J08M3]

Originally Posted by BimmerRob08

I wonder if over time, is it going to cause problems on fouling the plugs, cylinder's, etc? I think I'm already noticing a slightly higher fuel consumption of about .5 to .8 mpg since the light came on and I'm not driving it any different than before. Thanks,

It shouldn't have any effect on performance or MPG

[Lemans_Blue_M]

Originally Posted by BimmerRob08

Thanks for explaining. So that brings up a question. If now I have HFC with my X-pipe. stock ECU software and even before it through a CEL or after I clear it. Let's say a few thousand miles go by with no CEL. is my engine then not running at it's optimum fuel/air mixture because the pre & post O2 sensors are sensing something different than stock perameters? Or will the mixture be incorrect causing other problems down the road only if the CEL comes on as then the ECU detected a problem?

I wonder if over time, is it going to cause problems on fouling the plugs, cylinder's, etc? I think I'm already noticing a slightly higher fuel consumption of about .5 to .8 mpg since the light came on and I'm not driving it any different than before. Thanks,

Pre-cat O2 sensors are responsible for ~99% of the tuning adjustments, while the post-cat O2 sensors are only responsible for ~1%. Based off post-cat sensor data the ECU receives, very minor A/F fine-tuning adjustments can be made.

Without any reliable data from the post-cat O2 sensors, the car will still function virtually the same, but with a very, very slight handicap. (you can't really to tell the difference in power since the impact is so small)

Fuel consumption does increase by a small amount, since the car will tend to skew slightly rich in that situation.

So yea, technically speaking, the rear O2 sensors do actually play a small role in the overall tuning of your engine. (but not enough to make significant difference one way or the other)

BTW: There is no such thing as an "irrelevant" engine monitoring sensor on a modern BMW car.

[///FCB]

Originally Posted by BimmerRob08

From what other's say, you can either invest about $<100 for a code reader and just reset it or pay $$$$ for a tune and risk voiding the warrenty, unless it's a Dinan tune. That should take care of the CEL's comming on when ever. I won't be living in California when I get this M3 back to the States but if there is a visual inspection like in Cali (I think), then you would have to go back to stock to pass. Don't know what every one else in Cali is doing. I'll admit, it's a pain to have to change it out every year or two. I'm wondering if I want the hassle too. But I just spent $1800 on it, so don't want to waste the money and sell it off or store it in my garage for nothing. Just depends on what you are willing to do.

thanks for the reply..I have a buddy who has one of those code readers, so I'm hoping that will do the job because I don't want to ECU tune at the moment and/or lose the warranty


btw, Lemans Blue M, are you a undercover M engineer?

[MMMorish]

Originally Posted by ///FCB

btw, Lemans Blue M, are you a undercover M engineer?

I was just thinking the same thing.

[Nawaaz]

Originally Posted by ///FCB

btw, Lemans Blue M, are you a undercover M engineer?

hmmm. Off topic, but I've always pictured LMB as this guy:

[BimmerRob08]

well, in a few days or so I'll have the code reader and I'll reset my CEL. Hope it's not something frequent. Sounds like it won't hurt performance as mentioned but depends on how often it'll trigger a CEL. Thanks for the knowledge fella's.

[DLSJ5]

Originally Posted by MMMorish

I have an exhaust coming and I'm thinking about doing the x-pipe as well. Looking into the Fabspeed with resonators (want to keep it civil). My questions are:

1. Without a tune, will it cause a CEL to come on?

2. Will it increase the amount of drone in the cabin?

3. Will it be a lot louder?

Thanks for your help.

Nick

Here's what I experienced with the EI X pipe and HFC's.

1. YES

2. No, if you run it with the stock Muffler.

3. Yes, (stock Muffler) only when you get on it though, cruising it is not much louder than stock. With the Borla Muffler on mine it is a good amount louder.

[Bob MG]

Originally Posted by MMMorish

+1

So if I don't plan on removing my primary cats, then doing an x-pipe is pretty much useless?

As a daily driver, I'm not sure I want to do that to my M3. May be a bit too much drone and way too loud for me.

I've been through the excercise of Remus mufflers and fabspeed x pipe with HFCs. Great performance but too much drone for a daily driver.

Fit an Akrapovic full system, little bit more than standard sound by about 15% and zero drone. Perfect fr daily driver and big HP from an exhaust. But you must do a tune to avoid a cel. Any HFC will give you one without a tune

[BimmerRob08]

I'll back that up. I first had my EI x-pipe mated to the stock muffler. Sounded great and no drone at cruise @ 2900-3200rpm 6gr. Now I have installed the Remus Sport, sounds even better but a little drone at cruise rpm's. mainly at about 75-85mph on the highway is it a bit irritating but nothing bad. I don't mind it and glad I didn't go Remus Race or it would have been too much for daily use.

Got the dealer today to reset the CEL. No problems and hasn't come back. He explained that just as posted earlier above that the code showed the front O2 sensors kicked off the CEL. I would have thought the exit (rear) O2 sensor would show the change in electric signal as it's down stream. But anyway, all good. If it comes back on, I'll have my OBDII reader by then and will just clear it. Not too worried at this point.

[JC919]

Is there any way to fix a CEL cause by high flow cats and an x-pipe?

[BimmerRob08]

Originally Posted by JC919

Is there any way to fix a CEL cause by high flow cats and an x-pipe?

Nothing to actualy fix as the HFC are not causing any damage to anything. The O2 sensors just pick up the increased emissions and trigger the CEL. The dealer or anyone with a CANBUS OBDII code reader will just plug in, read the code(s) and clear it. That's all they did today as there isn't anything to fix. I ordered a OBDII reader (inexpensive~ $100) and if it comes back, I'll just do what the dealer did. Plug it in, read the code and clear it. Not a big issue, unless it comes on like every 100 miles. Then that'll be a pain in the ass.