[JustAnotherN54]

Sorry in advance, long post.

About the car:
2007 335i 6mt, prior to downpipe install mods are BMS 7.5 RACE intercooler, BMS chargepipe with tial BOV and BMS vacuum adapter for 1/4 line, JB4, BMS dual cone intakes, BMS dual catch cans, Ngk 1 step colder plugs gapped to .022. Mods were installed together around 2 months ago, ran fine. Car does presently have a dinan stage 2 flash original owner had on it (havent gotten around to flashing over it with BEF, was worried about complications from dinan encription). Jb4 set to map 1.

This week I installed my VRSF downpipes after discovering I pulled out my rear turbo inlet, had to remove dps anyways. Fresh gaskets to mid pipes and turbos, vband clamps fully seated all the way around, not in way of wastegate.

After install upon starting up I realized I mixed up my front o2 sensors and car was running horribly, shaking in cabin, 2c24 lambda muddled pre cat code, 20 AFR, practically stalling out at idle.
I switched them back and no more codes (except catless downpipe detected on jb4) but car idles horribly, seemed to have gotten a bit better after first few drives but still pretty lumpy. Both front and rear o2 sensors in correct position. Also after install seems the battery is drained every morning, which is new, most likely not relevant but just in case. I charge it every morning, drive it a bit then cant turn it over again. Will test alternator today. No codes for battery drain.

Also I belive the downpipe is making slight contact but I cant imagine that would cause such a rumble only at idle. If you had this issue caused by the VRSF pipes making contact, how'd you manage to get better clearance?

So my question(s) is, given no codes except the downpipe detected codes, could this simply be the cars o2 sensor calibration and fuel trims all messed up from when the o2 sensors were mixed and the ECU needs time to adapt? Would resetting that through jb4 menu 1/7 reset that?

I've searched around on multiple forums for three days, nothing that has helped.

Any help, advice, guidance would be appreciated!! I am totally lost lol and it's getting to be rainy enough here that I probably shouldn't take my motorcycle to work any longer. Sorry for the long post! Thanks!

[JustAnotherN54]

Btw if relevant car has 102000km (about 63k miles), walnut blast was just done less than 1000km ago, turbos have no rattle and only have 58000km on them. No boost leaks or misfires. Just the idle rumble after downpipes.

[whyzee125]

Yes I think it’s very likely an adaptation reset is needed. Also very likely your battery is toast which can cause a whole host of issues.

I would replace the battery, reset adaptations, and drive it

[JustAnotherN54]

Thanks for your reply! Yeah my battery was toast, replaced it this morning. I'll reset adaptations and see what happens!

[JustAnotherN54]

Update: reset adaptations, drove it a good while, still happening.

I removed the dinan software and flashed back to stock to see if maybe dinan just didnt agree with the mods, no luck.

Once warmed up, at a stoplight idle did fluctuate a bit from the usual 600rpm and hovered around 750rpm for 45 seconds or so before dropping. Idle felt better at 750 than it does at 600.

Possible culprits I can see are
1) o2 sensors being damaged, although I assumed this would throw a code.
2) leaky injectors, although my plugs are never wet. And this didnt happen before.
3) something making contact causing massive increase in vibration
4) something else fuel system related? Hpfp? Lpfp?
5) vacuum leak

Cant tell if it's just an air fuel thing or a misfire but feels like a misfire at idle, only at idle, again no codes nothing but feel to tell me this. Will keep updating until this is figured out, hopefully someone finds it useful.

[CarAbuser]

If the vibration started after downpipe install then it's almost certainly the downpipes contacting the frame.

VRSF have terrible quality control so you might not be able to fit the downpipes without them touching.

[Chapperss]

It`s strange it has happened after the install - I would be looking at the 02 sensors, especially with a rough/fluctuating idle.

The cables /wires can get damaged through twisting when doing this job. There are ways to test them, i`ll let you google that though as I dont know how.

I`ve recently done my DP`s and have had issues with the pipes contacting the steering column and you can tell its not the engine and it doesn`t affect revs.

[JustAnotherN54]

Thanks for the replies! I'm gonna try rotating the DPs again, although last time I couldnt seem to get them to rotate any more without making contact if they are going to line up with the mid pipes. After the struggle with the v-band clamps I really dont want to take them fully off again LOL

Chappers, I assume you're RHD (I'm LHD) but did you have the vibration in cabin issue when the dps contacted your steering column? Any metal on metal contact should theoretically cause the same issue then. Just strange it's only at idle.

Yeah the o2s, especially the fronts, I did twist the **** out of them, with my oil catch can line getting them out and in again seemed too much. I went the stupid route and back-twisted them. I just assumed they'd throw codes if damaged.

Will update after I try rotating them again in the morning.

[Chapperss]

Originally Posted by JustAnotherN54

Thanks for the replies! I'm gonna try rotating the DPs again, although last time I couldnt seem to get them to rotate any more without making contact if they are going to line up with the mid pipes. After the struggle with the v-band clamps I really dont want to take them fully off again LOL

Chappers, I assume you're RHD (I'm LHD) but did you have the vibration in cabin issue when the dps contacted your steering column? Any metal on metal contact should theoretically cause the same issue then. Just strange it's only at idle.

Yeah the o2s, especially the fronts, I did twist the **** out of them, with my oil catch can line getting them out and in again seemed too much. I went the stupid route and back-twisted them. I just assumed they'd throw codes if damaged.

Will update after I try rotating them again in the morning.

For some reason I thought you Canadians were RHD.

If it`s just vibration then yeah get in there and rotate - I had to do the same with mine to get it off the subframe and then again to get it away from the Steering column (really is a precise job).

Loosened the Vbands (didn`t remove the bolt or the band) separated from the exhaust, also undid exhaust mid hanger, and then used a pry bar against the sub frame and various other solid bits down there to force them to rotate. Probs not the best for the Turbo to DP gasket but seems to have worked

Good luck

[JustAnotherN54]

Update: rotated as much as possible, made maybe 1mm rotation, but they still contact in some areas. Issue seems to be gone at idle though! So it is from downpipe contact. Now they only do it when braking in neutral. But when idling they arent doing it, so it's enough to live with. Doubt they can rotate further than this and still line up to the midpipes, so for now the solution is staying in gear coming to a stop.
Thanks for the help guys!

[CarAbuser]

Originally Posted by JustAnotherN54

Update: rotated as much as possible, made maybe 1mm rotation, but they still contact in some areas. Issue seems to be gone at idle though! So it is from downpipe contact. Now they only do it when braking in neutral. But when idling they arent doing it, so it's enough to live with. Doubt they can rotate further than this and still line up to the midpipes, so for now the solution is staying in gear coming to a stop.
Thanks for the help guys!

You are having the exact same problem I had. I purchased new VRSF pipes and they touched the subframe. I could just about get enough movement to keep them off the subframe at idle but they would still touch sometimes during cornering.

I ended up sending them back and doing a chargeback (since they refused the return originally) then buying some used VRSF downpipes on this forum, they were an older revision and fit much better. At some point in the last year or so they hired Stevie Wonder to do their fabrication and things have gone downhill for them.

[R3dLeader]

Regarding the cabin vibrations and downpipes contacting subframe: there is an additional adjustment you can make rearward of the midpipe connection which will help pull both downpipes one way or the other. There is a youtube video form Vehicular DIY showing how to do this.