Issues after installing Akrapovic Evolution with Delete-R

[MartinS]

Hi guys.

Two weeks ago I installed my Akrapovic Evolution system with the Delete-R.
It sounds good but the car has a new strange sound now which I don't believe should be there.

It's difficult to explain how it sounds but it's almost like when a 2-stroke engine is 4-stroking. Know what I mean?? I hear it most when I have let go of the power (revs dropping and not applying power). I didn't hear this before installing the Akrapovic exhaust.

Another issue is that sometimes on downshifts (DCT) the engine doesn't rev up (blips the gas). I can hear that it tries to but it just don't happen or sometimes the exhaust makes a big BANG! This started just before I changed exhaust.

The day I changed the exhaust I had the car connected to the BMW-tester and it showed that there was a fault on the "hot-film air mass meter, secondary air system". I hoped that changing this part would remove the problem when downshifting but I just changed it today and it didn't help.



Actually the new air mass meter also shows incorrect values but I don't believe that I got a bad one from BMW. It shows that air is flowing even when the engine is shut off. Can this have something to do with the Delete-R?

Does anybody have an idea of what could be wrong?

/Martin.

[BIGW0RM]

Bummer man. Try removing the deleter to see if things clear up?

[MartinS]

Guess it was our tester that had a problem because now the new air mass meter reads correct values.

The mechanic found 3 places that the exhaust was touching the chassis so I hope that the strange sound is gone now. I'll find out after work. Guess I didn't do a perfect job installing it.

The Delete-R had northing to do with this.

Originally Posted by ILSMKU

Bummer man. Try removing the deleter to see if things clear up?

[Dave07997S]

The S65 has no mass air sensor..

[signes]

Originally Posted by MartinS

Hi guys.

Two weeks ago I installed my Akrapovic Evolution system with the Delete-R.
It sounds good but the car has a new strange sound now which I don't believe should be there.

It's difficult to explain how it sounds but it's almost like when a 2-stroke engine is 4-stroking. Know what I mean?? I hear it most when I have let go of the power (revs dropping and not applying power). I didn't hear this before installing the Akrapovic exhaust.

Another issue is that sometimes on downshifts (DCT) the engine doesn't rev up (blips the gas). I can hear that it tries to but it just don't happen or sometimes the exhaust makes a big BANG! This started just before I changed exhaust.

The day I changed the exhaust I had the car connected to the BMW-tester and it showed that there was a fault on the "hot-film air mass meter, secondary air system". I hoped that changing this part would remove the problem when downshifting but I just changed it today and it didn't help.



Actually the new air mass meter also shows incorrect values but I don't believe that I got a bad one from BMW. It shows that air is flowing even when the engine is shut off. Can this have something to do with the Delete-R?

Does anybody have an idea of what could be wrong?

/Martin.

Does it almost sound like a fluttering sound?

[spool twice]

Originally Posted by Dave07997S

The S65 has no mass air sensor..

+1

Are you getting any types of ghost codes such as a BMW specific 275E or 275D?

[MartinS]

Originally Posted by spool twice

+1

Are you getting any types of ghost codes such as a BMW specific 275E or 275D?

Call it what you want, I call it the same as the BMW tester.

[MartinS]

Originally Posted by spool twice

+1

Are you getting any types of ghost codes such as a BMW specific 275E or 275D?

What is a ghost code?

I have no errors now but the sound is still there.

What is fluttering? It's that sound all Akrapovic Evolutions make, or?

[MilehighM3]

Originally Posted by spool twice

+1

Are you getting any types of ghost codes such as a BMW specific 275E or 275D?

Actually the secondary air pump has a small MAF on it to monitor it's incoming air. The OP says it's already been replaced though.
OP- did you change anything else besides the exhaust? The black hard plastic pipe connected to the intake charge pipe is the inlet to the air pump. Make sure it's connected properly and there are no leaks between it and the pump. Also check your connections between the pump and non return valves on the back of each cylinder head.

[MartinS]

Originally Posted by Bmw135er

Actually the secondary air pump has a small MAF on it to monitor it's incoming air. The OP says it's already been replaced though.
OP- did you change anything else besides the exhaust? The black hard plastic pipe connected to the intake charge pipe is the inlet to the air pump. Make sure it's connected properly and there are no leaks between it and the pump. Also check your connections between the pump and non return valves on the back of each cylinder head.

No, only exhaust was change.

The pipe comes with the MAF so it was changed too. There is no faults anymore but still a strange sound.

I bought the 2 EGR valves too because I thought that maybe the were no closing/stopping air when there were supposed to but I found out that it takes more than 8 hours to change them so haven't done that and since the tester doesn't show a fault on them I'm not sure I want to change them.

Do you agree that if one of the EGR valves is open when it shouldn't it would make a strange sound? That's my theory.

[spool twice]

Did this happen directly after these two incidents?
Does this happen when the engine is on all the time? cold start only, warm start only?
Do you have a way to read BMW specific codes at the moment?

I'm starting to wonder if they installed your O2 sensors backwards (pre-cat where post cat is, and vice-versa). Secondary "MAF" should only matter when the secondary air-pump is running though correct?

[MilehighM3]

Originally Posted by MartinS

No, only exhaust was change.

The pipe comes with the MAF so it was changed too. There is no faults anymore but still a strange sound.

I bought the 2 EGR valves too because I thought that maybe the were no closing/stopping air when there were supposed to but I found out that it takes more than 8 hours to change them so haven't done that and since the tester doesn't show a fault on them I'm not sure I want to change them.

Do you agree that if one of the EGR valves is open when it shouldn't it would make a strange sound? That's my theory.

The non return valves could cause faults, but the likelihood of them both failing at the same time are slim to none. If the fault doesn't come back, you may have fixed it with the MAF replacement. Keep in mind that the secondary air system is only active on cold starts so it could take a couple days to see a warning light. It will take 2 fault occurrences on this type of fault to set a warning light. The non return valves sticking closed would cause faults for flow rate too low, and typically on one bank. I would be more inclined to replace the pump rather than the valves next, especially if the pump isn't sounding right. Is the noise higher pitched than it used to be or a grinding type of noise? If so that could indicate the beginning of end for the pump. The only other possibility that comes to mind are the pre cat O2 sensors. They are what is responsible for monitoring the pumps operation in comparison to the MAF reading on the input side of things.
The non return valves are not easy to swap so make sure that's really what it needs before digging into it. Pulling the plenum off will give you decent access to them, but it's still going to be a pia.

[MartinS]

Actually the sound isn't there when the engine is cold. It comes after a few minutes and stays until I shout the engine down.

I don't think it possible to mount the O2 sensors backwards (I did the install myself with a friend). As I remember the wire-connector wasn't the same on pre- and post-cat sensor.

I work at a BMW dealer but we haven't got experience with M cars since almost nobody has them here in Denmark. The mechanics says it's the exhaust and that I should keep it stock but they don't know what they're talking about.

[MilehighM3]

Originally Posted by MartinS

Actually the sound isn't there when the engine is cold. It comes after a few minutes and stays until I shout the engine down.

I don't think it possible to mount the O2 sensors backwards (I did the install myself with a friend). As I remember the wire-connector wasn't the same on pre- and post-cat sensor.

I work at a BMW dealer but we haven't got experience with M cars since almost nobody has them here in Denmark. The mechanics says it's the exhaust and that I should keep it stock but they don't know what they're talking about.

If it's not a cold start noise then as you know it isn't the air pump making the noise. Could it be the vacuum pump you're hearing? Pump the brake pedal and see if it cycles or not. Since you're a dealer guy I'm sure you know all about that setup. Otherwise it must be the exhaust, so leave it on. Stock exhaust is ugly and practically silent. Nobody likes those traits on an M car!