Increased emissions + SES

[Ubersmooth]

Trying to see if anyone has dealt with a similar issue, every couple of weeks my SES light and increased emissions warning pop up on the car, checked the code and got a misfire in cylinder 7, but the car is not misfiring at all. I come from the N54 world so I'm very very familiar with misfires

If I clear the code it's gone for a few weeks then comes back. I ordered some spark plugs + coils just to knock them out anyway, but I'm not sure that's gonna fix the issue since the car drives exactly the same with or without the SES and emissions warning (nice and strong).

I've read through other threads with the emissions warning and SES, but nearly all of them noted a difference in drivability or going into limp mode, which thankfully I'm not experiencing.

Appreciate any helpful advice, thanks!

[nurburgracer]

Originally Posted by Ubersmooth

Trying to see if anyone has dealt with a similar issue, every couple of weeks my SES light and increased emissions warning pop up on the car, checked the code and got a misfire in cylinder 7, but the car is not misfiring at all. I come from the N54 world so I'm very very familiar with misfires

If I clear the code it's gone for a few weeks then comes back. I ordered some spark plugs + coils just to knock them out anyway, but I'm not sure that's gonna fix the issue since the car drives exactly the same with or without the SES and emissions warning (nice and strong).

I've read through other threads with the emissions warning and SES, but nearly all of them noted a difference in drivability or going into limp mode, which thankfully I'm not experiencing.

Appreciate any helpful advice, thanks!

In the meantime, you could perhaps swap the coil from another cylinder. If no difference, return the coil to the original cylinder and exchange plugs with another cylinder. If the fault moves with the part to the other cylinder, that's the part that's faulty. It's important that ou only change one thing at a time.

Let us know the result.

[SilverSlug]

I've had the exact same issue forevaaa

It could be failing primary cats, bad O2 sensor/s, stuck secondary air pump, bad plugs.

What mods are you running? Any exhaust mods? How old are the plugs?

[Ubersmooth]

Originally Posted by SilverSlug

I've had the exact same issue forevaaa

It could be failing primary cats, bad O2 sensor/s, stuck secondary air pump, bad plugs.

What mods are you running? Any exhaust mods? How old are the plugs?

Hey man. Stock car, actually just changed the plugs to see if that would fix it. Car runs super smooth but I'm still getting the increased emissions + SES with a code for a misfire in cylinder 7. Haven't been driving the car much so I really wanna get it solved asap. You ever figure out what it was?

[Ubersmooth]

Really regret not just ordering coils and doing that while I was changing plugs but I'm not sure they would've been the solution

[SilverSlug]

I'm fairly certain the cause of this is a very minor exhaust leak.

Apparently there is a common leak that develops at the doughnut flanges that connect the mid pipe.

I didn't even realize mine was leaking (and even passed smog with it), but it finally got worse and worse to a point where I could hear it louder and louder.

Finally it got progressively worst in one day of driving that the care went into reduced power mode ("limp mode").

I've not had time to replace it yet due to holidays, but plan to do so in the coming weeks when I get home.

[SilverSlug]

If you're a DYIer, take a long rubber hose and use it as a stethoscope (check near the mid pipe and under the heat tray near the headers).

If you prefer to take it to a shop… Have them use a smoke machine to smoke out the leak.

[Ubersmooth]

Originally Posted by SilverSlug

If you're a DYIer, take a long rubber hose and use it as a stethoscope (check near the mid pipe and under the heat tray near the headers).

If you prefer to take it to a shop… Have them use a smoke machine to smoke out the leak.

Curious what led you to think exhaust leak? I just took off my rear section to do the 2.5 pipe mod, didn't notice any leaks but I'll jack the car up and check again. I'm starting to think it may be pre cat O2 sensor as a few others are noting that on the forums.

I did get limp mode once but that seemed to be from a misfire before changing the plugs.

[SilverSlug]

I didn't even realize it was a leak either. The smog tech told me I have a leak, but passed it anyway since the check engine light wasn't on at the time.

Tall tale sign will be if you get the increased emissions message once you get the engine really warm and/or under some spirited driving. The metal expands under heat and increases the size of the leak.

The leak was very, very undetectable.

Turns out it is very common, and many people have this leak.

[Ubersmooth]

Originally Posted by SilverSlug

I didn't even realize it was a leak either. The smog tech told me I have a leak, but passed it anyway since the check engine light wasn't on at the time.

Tall tale sign will be if you get the increased emissions message once you get the engine really warm and/or under some spirited driving. The metal expands under heat and increases the size of the leak.

The leak was very, very undetectable.

Turns out it is very common, and many people have this leak.

Would the leak lead to a misfire code by any chance?

[SilverSlug]

Yup, I got misfires before the leak finally got really bad, and the individual misfires were accompanied by a random cylinder misfire code as well (and limp mode - reduced power kicked on).

[Ubersmooth]

Update: taking the car to a shop on Monday to get a second opinion. Had someone look at it and they are learning towards a failed valve spring, really hoping that is not the case.

Confirmed it is not O2 sensors after checking them with the ISTA software. Will have the shop perform a smoke test to check for any undetectable exhaust leaks.

Anything other than valve spring failure will be good news to me lol.

[SilverSlug]

Curious to know what yours turns out to be. Please update here when you find out!

[jp1984]

Originally Posted by Ubersmooth

Hey man. Stock car, actually just changed the plugs to see if that would fix it. Car runs super smooth but I'm still getting the increased emissions + SES with a code for a misfire in cylinder 7. Haven't been driving the car much so I really wanna get it solved asap. You ever figure out what it was?

I had something similar with a bad battery, tons of warnings but nothng to really diagnose, I changed my battery because I knew that was dying and it fixed the problem.

How old is your battery, is it on a tender?

[Ubersmooth]

Originally Posted by jp1984

I had something similar with a bad battery, tons of warnings but nothng to really diagnose, I changed my battery because I knew that was dying and it fixed the problem.

How old is your battery, is it on a tender?

Not sure how old the battery is, PO told me "it's only a few years old" when I picked up the car last April. I understand a failing battery can cause some weird stuff to happen, but increased emissions + misfire code?

It is not on a tender. I'll see if I can borrow a tool to check the voltage on the battery and see if it needs to be replaced before I drop the car off. Would be a nice easy solution if that was the case

[jp1984]

Originally Posted by Ubersmooth

Not sure how old the battery is, PO told me "it's only a few years old" when I picked up the car last April. I understand a failing battery can cause some weird stuff to happen, but increased emissions + misfire code?

It is not on a tender. I'll see if I can borrow a tool to check the voltage on the battery and see if it needs to be replaced before I drop the car off. Would be a nice easy solution if that was the case

Worth a shot and super low cost!

I had increased emissions pop up when my battery was low, I never found out if this information was accurate, but I read that since the battery is ingrained to the computers that when it gets low, it deprioritizes certain modules. As an example your comfort access doesnt work when your battery may be low. I never confirmed if that was actually true though.

[Ubersmooth]

To update the thread: it turned out to be an ignition coil. When I originally swapped the coil, the code did not follow. Ordered a new coil that ended up being defective, and after swapping that one around the code followed it. Headed to the BMW dealer last night and paid the tax to get a new one. Swapped it in and all is well again.