Downpipe Install brought Codes

[Josiiah]

Hey Everyone, I want to know if anyone has had a run in with these codes.

I bought some downpipes from eBay and installed them last weekend 5/17
I might need to rotate them because the exhaust won’t hook up. So I have an open exhaust after the downpipes. During installation the o2 sensors coming from the engine bay wouldn’t fully screw in (picture 1). The pair from the bottom screwed all the way. Do y’all think these code are from the open exhaust, the o2 sensor isn’t all the way in or, could I have ruined the o2 sensor during the installation? Throughout the week more codes kept popping up without me doing anything. I reply don’t think I switched the post cat sensors because of the length. Car is now really loud and raspy but also sounds like a lawnmower at certain throttle input. I can also hear the wastegate rattle now too

5/17 Dp installed. 5/18 I did the MHD DP fix and got two different codes.
An Indy said I would need some new DME since MHD says DME. I don’t think that is the case though. Is my car at risk running it like this? I’ve had these DPs for a few months. I was hesitant to install because I knew something like this would happen. Any help or input is appreciated!
I will post screenshot of codes in order.
Attached:

[ErvGotti]

Install your downpipes correctly and reset the codes and go from there. make sure the pre cat sensors are installed on the right downpipes, if the cat codes come back then it's time to replace them. It's easy to damage them and can cause the 2C9C 2C9D codes when damaged. Additionally the cheap Ebay pipes are known to have fitment issues when trying to line up with the midpipes.

[Josiiah]

Originally Posted by ErvGotti

Install your downpipes correctly and reset the codes and go from there. make sure the pre cat sensors are installed on the right downpipes, if the cat codes come back then it's time to replace them. It's easy to damage them and can cause the 2C9C 2C9D codes when damaged. Additionally the cheap Ebay pipes are known to have fitment issues when trying to line up with the midpipes.

Thank you Erv, the install was really hard. It took 3 days to get to the downpipes on. The clamp would close. The only thing I could think I installed it improperly is the rotation of the downpipe to fit the rest of the exhaust but how do I know if it’s the eBay fitment or if it’s me? In the first picture with the o2, would that be a problem, only screwed in halfway? Because I don’t think the bung is threaded properly for the o2. Also if my o2’s did go out, is that bad for my car? I have been daily driving this as it’s my only car.

[Josiiah]

Just spoke with my BMW Indy. They referred me to a good muffler shop. I will reinstall downpipes with the new Turbo to DP gaskets and the muffler shop will cut the flange from the exhaust after the downpipes and screw it the the downpipes. Then I’ll have him add some piping after the flange. After that I’m resetting the codes. My Indy said I would definitely hear an exhaust leak or o2 leak but my exhaust is really loud and it’s my first turbo and straight pipes car so there’s a lot of new sounds I’m not used to. The codes might pop up again after clearing and then I’ll know to replace the o2 and that should be a job done. I would definitely recommend vrsf downpipes because when you run into a fitment issue, you can’t tell if it’s you or the piping.

[drwillb]

Why not just buy DP from a known vendor/fabricator? Go with a brand with good feedback on their products.

Your making things more difficult in trying to make cheap parts work.

[r0nd3L]

Originally Posted by drwillb

Why not just buy DP from a known vendor/fabricator? Go with a brand with good feedback on their products.

Your making things more difficult in trying to make cheap parts work.

Agreed. OP's approach in the last post is wrong way to go about it. Don't go start hacking other parts of the car such as mid-pipe to account for crappy parts or install.

How far off is the fitment? Did you follow proper procedures of loosely fitting everything together and then tightening v-bands first and midpipe flanges second? If you did and it still didn't fit, plus considering jacked up O2 sensor bungs, I would consider getting quality downpipes and call it a day.

[Josiiah]

Hey Rondel, the exhaust will reach the downpipes but I can’t bolt them both. When I bolt one side of the exhaust the other pulls with it and then the second DP won’t reach the unbolted side/sit flat on the flange. If the fitment were to be bad I wouldn’t have known where so when I got it on I just tightened it(I was also really tired and out of time). The first DP fit good so I figured that fitment wasn’t a problem. I’m going to try my hardest before I just say bad fitment, give up and buy new VRSF. The reason the o2 bung didn’t push me over is because I figured it went far enough and my Indy said it should be fine. I’m going to rotate the DP Friday night and see if I could get it. The install took 3 days to get the flange on the DP sitting how it is and I had to get a longer bolt for the flange to close. It’s just when I rotate the DP as it sits flush it would come off. I’m new to working on cars but YouTubers makes it seem easy so I tried it. I really appreciate your guys input. Also, if I were to go to the muffler shop, wouldn’t it just be like getting a custom exhaust? I mean really my only problem is the o2 sensors. This is also my first and last eBay purchase.

[dtla1]

The downpipe fitment is tricky, specifically getting those v-bands on. You shouldn't need longer bolts, if you're using longer bolts to help get it started that's one thing, but you could also be not totally clamped at the turbo, just that the longer bolt is providing enough clamping down force even though it's cocked wrong so that it stays.

As someone else mentioned, loosen up the v-band enough so you can spin/twist the downpipe to match the orientation of the mid-pipe.

I know this is an ebay purchase, but still, most of the time these things are made on jigs, and it's possible that whoever made this one might also make some other brand, for example (not saying this is the case) VRSF stuff might be designed in the US, but it's well known some (all?) of their stuff is made in China. I mean for all we know the ebay stuff is made in the same jig, just on off hours, so the welding might be worse, or doesn't have the same level of prep or something.

[Josiiah]

Understood and thanks DTLA, I will be going back to do the job again. I need to put new turbo to DP gasket anyways. I will use the long bolt again, tighten it so it holds then loosen it and rotate it to find the proper orientation. Then hopefully the clamp will be a like to fit the oem bolt, and go from there. But this has nothing to do with the codes don’t they? You think I just damaged the o2s during install? I still don’t know what happens when you have bad o2 sensors. Sometimes now when I start my car there’s a bit of smoke by the passenger headlight. It’s not continuous, just when I start it I see smoke there for a few seconds. I can’t smell it either because all I smell now is the co2 from not having �� s. Thanks for the fitment details. I still think the fitment is okay because the first clamp didn’t need a longer bolt but I don’t know.

[dtla1]

The poor fitment could be related to your codes if the sensor is getting a lot more fresh air due to a leak.

[Josiiah]

I put new turbo to DP gaskets in but it’s so hard getting the DPs on. The rear is the first to go on and the wastegate actuator is really getting in my way(first picture). The v-band clamp is hard to adjust and rotate because if it. The actuator also makes the clamp fall off in the far back and I can’t get to it. But I did it before I guess. I also read that the black o2 is the rear so I swapped that. If that’s correct my o2 codes should be gone unless I ruined them during install. Biggest problem is fitting the DPs back on Last week I started on Saturday morning and finished Monday night. Hopefully it doesn’t take so long. There are absolutely no DIYs specifically for the 135i N54 but oh well. Back to work!

[Josiiah]

THE JOB IS DONE
Thanks for your help guys! I eventually got the downpipes on and left them a bit loose to adjust although that didn’t help much but hey I got it. I also swapped the o2 sensors, the rear turbo gets the grey o2 and front, black. Car sounds great and all. I cleared the codes and drove to get some beer and pizza haha. Car feels better and no other codes have popped up. The only “downside” is I don’t hear the turbos anymore. Anyways, Im glad I didn’t ruin any o2 sensors or have to go to the muffler shop. Just saved probably just under a grand. Thanks guys <3 BTW will never do this again lol

[dizzy619]

I'd have rather paid a grand than have all that hassle for a week

[Josiiah]

Originally Posted by dizzy619

I'd have rather paid a grand than have all that hassle for a week

It was more just my errors. I swapped the o2s on accident and failed to put new gaskets. I had a good experience though and learned a lot. I’m happy about it and only spent $170

[drwillb]

Originally Posted by Josiiah

It was more just my errors. I swapped the o2s on accident and failed to put new gaskets. I had a good experience though and learned a lot. I’m happy about it and only spent $170

Persistence is the name of the game with car work. Good job. You’ll apply some of what you learned on your your next project and then others.