With this car it has been all about the OEM+ mods I could do with used parts (looking back). From this forum I happened upon a local low mileage 335is exhaust so I thought it would be a nice addition. I loved how the 335is had different exhaust tips and sounded amazing in videos that I had seen online, while retaining an OE exhaust. I will say after installing it that it does drone a bit under 3k, but the E90 interior is so quiet it is almost unnoticeable. I could see adding a couple resonators in the future, but it is fine for now. It is definitely a step up in loudness, but in a great way
Unfortunately the only picture I have of it from the seller:
I was driving the car even more now as my graduate program was coming to an end. Back and forth from college to home sometimes a few times a week racked up the miles for a few months, but it was all smooth and the E90 soaked up the miles. I did a bit more maintenance in my free time like Eldor coil packs but otherwise the car remained trouble free.
Cleaned up the wiring harness above the valve cover with some zip ties. It always bothered me how they were loose and hanging around:
I found myself wanting folding rear seats and had scrounged the hardware from a local junkyard, just needed the saddle rear seats. I found a local part out that had a set and traded my non-folders for his folders.
I still need to install the folding rear seat belt, just didn't want to remove the rear parcel shelf at the time.
Next to my brother's E36 M3 at a local car show:
The car eventually threw a shadow 29E0 code (no CEL, just caught from a general preventive scan). So I did a bunch of reading and started monitoring fuel trims / AFRs. The general consensus seemed to be that either a fuel injector was throwing the mixture off (not flowing enough / poorly), or an oxygen sensor was due for replacement. I did almost everything I could to narrow down the issue without needlessly buying parts. From pulling O2 voltages with INPA, to checking spark plugs for gap and fuel (none present), and running a pressure test on the intake system, I was a bit stumped for a while. The issue was also quite intermittent for me, and the car ran perfectly fine.
During an oil change I decided to stick a new to us inspection camera around the turbos / oxygen sensors and found what appeared to be a cracked bank 1 oxygen sensor. I could tell from the traces of white around the base of the sensor and that was enough of a smoking gun to order both upstream oxygen sensors. As far as I could tell they had never been done and at 110k miles, they were due for replacement anyways.
Cracked bank 1 O2:
I actually have a
pretty extensive thread around this with steps I took through diagnosis. I always find mixture control issues a bit tricky to diagnose without spending a ton on parts that may or may not be bad. Luckily for me, this turned out to be the issue and the shadow code hasn't returned for over a year now. It seems the upstream O2s needed replacement in general, and I'll be changing them out at regular intervals moving forward.