KKS exhaust system

Subw00er · 04-14-2009, 12:04 PM

Where can I buy this butterfly valve exhaust?

Does anyone have any experience with it? I'm a little concerned about the sudden change in exhaust backpressure and its affect on the learned ecu programming (ie it couldn't keep up because the ECU learns over time). Is this an issue?

J08M3 · 04-14-2009, 12:43 PM

I think it's not an issue... Why would the ECU care if there's a change in backpressure?

BimmerRob08 · 04-14-2009, 04:44 PM

I wouldn't think so either but my experiance was with my '04 Saab 93t Aero. It was about 6 months old when i bought a Borla exhaust (muffler) only. Now I know it's a turbo but what happened is, after the exhaust shop drove it from one shop to the main office where I was, everything was fine. Once I jumped in after about 10 minutes and started it up, it ran fine intercity until I got on the highway and started to excellerate, I noticed large turbo lag, and also rpm's were limited. It did this for about 20 minutes of highway driving. Got home, shut down. Later had to go to work and when I started it up, it ran fine the rest of the time. Saab dealer told me that it may have been the ECU getting used to or learning the new exhaust back pressure. Maybe, but now I've sold it to a girl friend and just a few months ago that same Borla muffler fell off from rust, etc. She's been driving it all this time without the muffler and the engine has been working fine all the time. So maybe the ECU re-programs itself with difference back pressure changes, at least that's how it seemed. But I've not read about anyone on the post with the M3 having these issues. So do you have any idea's? knowledge on how the ECU works? Why the rpm & turbo lag for a intermediate engine run? I know for sure that the ECU's or DEC's (digital electronic control) on most modern jet engines for example are self-trimming. As inlet pressure changes with altitude/temperature, the DEC constantly calculates the EPR (engine pressure ratio) and meters fuel and Inlet guide vanes appropriately. I know I'm talking jet engines now but electronic controls are pretty modern now and I don't see why an ECU on a new car would NOT moniter and change parameters depending on inlet/exhaust pressure. I don't know the answer, but I think it's part of the designed the engineers had in mind.

Subw00er · 04-14-2009, 11:08 PM

I guess the question is... how often does the ecu relearn sharp changes? For example, if its raining out, with a higher humidity, the ecu will obviously sense this, but will it change its programming to accommodate? Its wont be raining tomorrow right? So I would assume that if it were raining for a week straight, it would then relearn the humidity.. This is all speculation, I don't really know, but I think the learning on most ECU's is quite a lengthy process, including engine on/off sequences.

BTW, I dont think you're heard about it on the forum because I dont think these exhausts are very popular. I havent seen anyone that owns one yet.

J08M3 · 04-15-2009, 08:51 AM

I'm pretty sure ECU doesn't care about humidity either

Subw00er · 04-15-2009, 09:00 AM

how could it not?!

BMRLVR · 04-15-2009, 01:25 PM

Automotive engines do not measure back pressure. They measure barometric pressure and manifold pressure (some engines that use a MAF sensor don't even measure manifold pressure). Some engines measure EGT but they are few and far between, the only common thing measured on the exhaust side of all automotive engines is Mixture via the-pre cat O2 sensors.

The only way an ECM could adapt to an exhaust modification for performance gain would be through more complete scavenging. Better scavenging would mean a cooler cylinder temperature allowing more timing as well as a better intake charge that is less diluted with exhaust gases that were not scavenged on the previous stroke.

Subw00er · 04-15-2009, 01:42 PM

Jamie, so what are you saying.. that the sudden change in exhaust behavior with a valve system wont matter?

J08M3 · 04-15-2009, 02:51 PM

Quote:

Originally Posted by Subw00er

Jamie, so what are you saying.. that the sudden change in exhaust behavior with a valve system wont matter?

04-14-2009, 12:04 PM	#1
Subw00er Bates '08 Interlagos Launch 126 Rep 1,230 Posts Drives: 440i xGC, ZL1, JCW Join Date: Nov 2005 Location: NY iTrader: (2)	KKS exhaust system - Where to buy and ECU learning? Where can I buy this butterfly valve exhaust? Does anyone have any experience with it? I'm a little concerned about the sudden change in exhaust backpressure and its affect on the learned ecu programming (ie it couldn't keep up because the ECU learns over time). Is this an issue?
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04-14-2009, 12:43 PM	#2
J08M3 Major General 286 Rep 6,007 Posts Drives: 2011 M3 COUPE Join Date: May 2008 Location: NEW YORK iTrader: (8)	I think it's not an issue... Why would the ECU care if there's a change in backpressure? __________________
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04-14-2009, 04:44 PM	#3
BimmerRob08 Major 110 Rep 1,311 Posts Drives: 2008 M3, Space Gray Join Date: Mar 2008 Location: KIKR (ABQ), NM iTrader: (0)	I wouldn't think so either but my experiance was with my '04 Saab 93t Aero. It was about 6 months old when i bought a Borla exhaust (muffler) only. Now I know it's a turbo but what happened is, after the exhaust shop drove it from one shop to the main office where I was, everything was fine. Once I jumped in after about 10 minutes and started it up, it ran fine intercity until I got on the highway and started to excellerate, I noticed large turbo lag, and also rpm's were limited. It did this for about 20 minutes of highway driving. Got home, shut down. Later had to go to work and when I started it up, it ran fine the rest of the time. Saab dealer told me that it may have been the ECU getting used to or learning the new exhaust back pressure. Maybe, but now I've sold it to a girl friend and just a few months ago that same Borla muffler fell off from rust, etc. She's been driving it all this time without the muffler and the engine has been working fine all the time. So maybe the ECU re-programs itself with difference back pressure changes, at least that's how it seemed. But I've not read about anyone on the post with the M3 having these issues. So do you have any idea's? knowledge on how the ECU works? Why the rpm & turbo lag for a intermediate engine run? I know for sure that the ECU's or DEC's (digital electronic control) on most modern jet engines for example are self-trimming. As inlet pressure changes with altitude/temperature, the DEC constantly calculates the EPR (engine pressure ratio) and meters fuel and Inlet guide vanes appropriately. I know I'm talking jet engines now but electronic controls are pretty modern now and I don't see why an ECU on a new car would NOT moniter and change parameters depending on inlet/exhaust pressure. I don't know the answer, but I think it's part of the designed the engineers had in mind.
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04-14-2009, 11:08 PM	#4
Subw00er Bates '08 Interlagos Launch 126 Rep 1,230 Posts Drives: 440i xGC, ZL1, JCW Join Date: Nov 2005 Location: NY iTrader: (2)	I guess the question is... how often does the ecu relearn sharp changes? For example, if its raining out, with a higher humidity, the ecu will obviously sense this, but will it change its programming to accommodate? Its wont be raining tomorrow right? So I would assume that if it were raining for a week straight, it would then relearn the humidity.. This is all speculation, I don't really know, but I think the learning on most ECU's is quite a lengthy process, including engine on/off sequences. BTW, I dont think you're heard about it on the forum because I dont think these exhausts are very popular. I havent seen anyone that owns one yet.
	Appreciate 0 Quote

04-15-2009, 08:51 AM	#5
J08M3 Major General 286 Rep 6,007 Posts Drives: 2011 M3 COUPE Join Date: May 2008 Location: NEW YORK iTrader: (8)	I'm pretty sure ECU doesn't care about humidity either __________________
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04-15-2009, 09:00 AM	#6
Subw00er Bates '08 Interlagos Launch 126 Rep 1,230 Posts Drives: 440i xGC, ZL1, JCW Join Date: Nov 2005 Location: NY iTrader: (2)	how could it not?!
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04-15-2009, 01:25 PM	#7
BMRLVR Grease Monkey 295 Rep 2,646 Posts Drives: 2011 E90 M3,1994 Euro E36 M3/4 Join Date: Apr 2006 Location: Fort McMurray, Alberta, Canada iTrader: (3)	Automotive engines do not measure back pressure. They measure barometric pressure and manifold pressure (some engines that use a MAF sensor don't even measure manifold pressure). Some engines measure EGT but they are few and far between, the only common thing measured on the exhaust side of all automotive engines is Mixture via the-pre cat O2 sensors. The only way an ECM could adapt to an exhaust modification for performance gain would be through more complete scavenging. Better scavenging would mean a cooler cylinder temperature allowing more timing as well as a better intake charge that is less diluted with exhaust gases that were not scavenged on the previous stroke. __________________ 2011 E90 M3 ZCP - Individual Moonstone/Individual Amarone Extended/Individual Piano Black With Inlay:LINK!!! 1994 Euro E36 M3 Sedan - Daytona Violet/Mulberry:LINK!!!
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04-15-2009, 01:42 PM	#8
Subw00er Bates '08 Interlagos Launch 126 Rep 1,230 Posts Drives: 440i xGC, ZL1, JCW Join Date: Nov 2005 Location: NY iTrader: (2)	Jamie, so what are you saying.. that the sudden change in exhaust behavior with a valve system wont matter?
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