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-   -   CEL emissions issue with Akropovic Exhaust (http://www.bimmerfest.com/forums/showthread.php?t=650370)

reltney5150 10-07-2012 07:55 AM

CEL emissions issue with Akropovic Exhaust
 
Anyone have any issues with the Check Engine Light coming on and staying on due to "increased emissions" and Akropovic Exhaust? I have brand new e92 (less than 300 miles) and put titanium exhaust on it. CEL has come on and idrive says increased emissions.

Any ideas on how to fix/prevent?

CT 10-07-2012 08:36 AM

Caused by CAT delete or insufficient O2 sensor ports. http://www.europeanautosource.com/pr...pressor-e9x-m3

gotrice415 10-07-2012 09:28 AM

If you have an N54 back pressure is critical for waste gate/turbo operation since the flap is actuated in exhaust.

Orient330iNYC 10-07-2012 10:21 AM

Quote:

Originally Posted by gotrice415 (Post 7118953)
If you have an N54 back pressure is critical for waste gate/turbo operation since the flap is actuated in exhaust.

this is not accurate. i have the oem performance exhaust, installed at the vdc and there is no exhaust flap. there is a stub to terminate the vac line. the valve is for low rpm noise reduction.

the op has a different issue.
Sent from my Galaxy Nexus using Bimmer App

CT 10-07-2012 12:08 PM

Quote:

Originally Posted by Orient330iNYC (Post 7119039)
this is not accurate. i have the oem performance exhaust, installed at the vdc and there is no exhaust flap. there is a stub to terminate the vac line. the valve is for low rpm noise reduction.

the op has a different issue.
Sent from my Galaxy Nexus using Bimmer App

This is exactly correct. The flap operation is purely for noise reduction at low throttle and low RPM due to European regulations. Back pressure is handled entirely through the design of the flow path itself.

gotrice415 10-07-2012 12:43 PM

Quote:

Originally Posted by Orient330iNYC (Post 7119039)
this is not accurate. i have the oem performance exhaust, installed at the vdc and there is no exhaust flap. there is a stub to terminate the vac line. the valve is for low rpm noise reduction.

the op has a different issue.
Sent from my Galaxy Nexus using Bimmer App

Ok so you just said it youself. How is that not accurate? There are dpdw's that control the wastegate which is vacuum to it. Since you have an exhaust installed by VDC im sure they blocked off the vacuum line and retrofitted the DME software to ignore or not activate the flap since it ha been deleted.

So if you dont do that what do you think the DME does? Sets a fault for activation and vacuum leak causes lean mixture faults.

roadkillrob 10-07-2012 01:46 PM

Quote:

Originally Posted by gotrice415 (Post 7119249)
Ok so you just said it youself. How is that not accurate? There are dpdw's that control the wastegate which is vacuum to it. Since you have an exhaust installed by VDC im sure they blocked off the vacuum line and retrofitted the DME software to ignore or not activate the flap since it ha been deleted.

So if you dont do that what do you think the DME does? Sets a fault for activation and vacuum leak causes lean mixture faults.

Do you have any idea what you are talking about???????????????

The flap on the tailpipe is for noise regulations only, blocking of the vacuum line has no effect on anything at all (won't even throw a code and certainly has nothing on earth to do with emissions).

Wastegates are on the turbos, not the exhaust flapper at the end of the tailpipe. Wastegates are vacuum controlled also (only thing you have correct) to control the volume of exhaust gas driving the turbines.

The DME measures the difference in pollution on the primary cats, there is a sensor before and after, 2 cats on the N54's, 1 on the N55's. Secondary cats are not monitored by the DME.

Now back to the actual question - Op lists that he has an M3, so no turbo's. My guess that something was damaged when the exhaust was installed, either wiring to the O2 sensors or an O2 sensor itself if they needed to be removed to install the exhaust - the car is seeing too much of a difference across the primary cats. M3 also has dual primaries with an O2 before and after, there should be no issue with the install going anywhere near those, so either the had to much with something up front or it is just a coincidence.

Rob

Orient330iNYC 10-07-2012 01:50 PM

Kimi
Quote:

Originally Posted by gotrice415 (Post 7119249)
Ok so you just said it youself. How is that not accurate? There are dpdw's that control the wastegate which is vacuum to it. Since you have an exhaust installed by VDC im sure they blocked off the vacuum line and retrofitted the DME software to ignore or not activate the flap since it ha been deleted.

So if you dont do that what do you think the DME does? Sets a fault for activation and vacuum leak causes lean mixture faults.

the exhaust valve flapper malfunction does not set a cel. if you unplug the flapper at the solenoid you throw a silent code in the dme indicating an open circuit. if you leave it unplugged there is no code as the component is not an emissions component. if you read the post by ct, the exhaust the op installed is catless, which will throw an emissions error code as there are no cats. the flap has nothing to do with emissions.

leaving the vac hose unplugged will NOT set an emissions fault or cause any kind of lean/rich condition...

Sent from my Galaxy Nexus using Bimmer App

gotrice415 10-07-2012 03:17 PM

Quote:

Originally Posted by Orient330iNYC (Post 7119341)
Kimi

the exhaust valve flapper malfunction does not set a cel. if you unplug the flapper at the solenoid you throw a silent code in the dme indicating an open circuit. if you leave it unplugged there is no code as the component is not an emissions component. if you read the post by ct, the exhaust the op installed is catless, which will throw an emissions error code as there are no cats. the flap has nothing to do with emissions.

leaving the vac hose unplugged will NOT set an emissions fault or cause any kind of lean/rich condition...

Sent from my Galaxy Nexus using Bimmer App

Wow, where does engine vacuum come from? I only do this day in day out for a living at a dealership. Yes you are right that the flap is meant for noise reduction. But how about you take a look at documentation on when and why the flap would open. So your tellin me that if you induce a vacuum leak it wont throw a code or cause a lean mixture issue? How about you test that theory and leave your oil filler cap off or disconnect a vacuum line under the hood. Vacuum is created by the engine with low pressure differential. With N54's there is a vacuum pump since adequate vacuum cant be established at higher rpms. Do a few drive cycles and let me know what you find.

CT 10-07-2012 05:18 PM

Quote:

Originally Posted by gotrice415 (Post 7119451)
Wow, where does engine vacuum come from? I only do this day in day out for a living at a dealership. Yes you are right that the flap is meant for noise reduction. But how about you take a look at documentation on when and why the flap would open. So your tellin me that if you induce a vacuum leak it wont throw a code or cause a lean mixture issue? How about you test that theory and leave your oil filler cap off or disconnect a vacuum line under the hood. Vacuum is created by the engine with low pressure differential. With N54's there is a vacuum pump since adequate vacuum cant be established at higher rpms. Do a few drive cycles and let me know what you find.

Wrong vacuum location. There's a vacuum-operated flap in the left-rear exhaust pipe just aft of the muffler. Has absolutely zero effect on engine back pressure or vacuum. Don't overheat there, buddy.

But hey, congratulations on flippin' your lid over trying to argue over the internet. Next time try getting the right subject, though, eh lad?


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