N55 w/ Downpipe Issue

[Gines135]

Hey everyone. I am having some trouble with my car lately and would like some advice on what to do about it. I have a N55 w/ DCT and BMS Stage 2 and BMS Catless Downpipe. After having the downpipe installed, i noticed that the idle would some times act up. It would drop and then rev. This only happened while i was at a stop just idling.

I noticed that once the engine was warmed up that it seemed to be ok but recently it seems to be getting worse. Today i got in my car after work, so it had been sitting for 9 hours and i came to a stop light. The engine died on me. It started right back up but im afraid it will continue to happen.

Has anyone else had this issue? Does anyone have any suggestions?

[seslait]

I currently have this issue. I'm running lean according to some logs I sent to Terry (Burgertuning). I have to see whether my O2 sensors are backwards or broken. Either way, that's the price you pay when you lose the cats.

To be honest, I've had a million issues since I went catless and I'll prolly go back. The power difference is significant though...

Originally Posted by Gines135

Hey everyone. I am having some trouble with my car lately and would like some advice on what to do about it. I have a N55 w/ DCT and BMS Stage 2 and BMS Catless Downpipe. After having the downpipe installed, i noticed that the idle would some times act up. It would drop and then rev. This only happened while i was at a stop just idling.

I noticed that once the engine was warmed up that it seemed to be ok but recently it seems to be getting worse. Today i got in my car after work, so it had been sitting for 9 hours and i came to a stop light. The engine died on me. It started right back up but im afraid it will continue to happen.

Has anyone else had this issue? Does anyone have any suggestions?

[Tony135]

I have this too but usually only on a cold start. I figured it was just the clutches on the DCT or something.

[Gines135]

Yeah, the power loss will suck but worrying about stalling out at a stop sign or a light is just ridiculous. I dont even want to go through a drive through because of that. So you haven't heard of any fixes or anything?

[Gines135]

Tony, mine is usually only when its a cold start as well but it seems to be happening more lately. Maybe because its still cold as hell outside? Don't think that should really make a difference though. Mine gets pretty bad, like i said, it completely died on me today and then if im coming up to a stop and im slowing down, it may rev and if im not on the brake it will definitely leap out.

[cooler2442]

I do not have this issue with my 2011 DCT.

I picked up the Stage 2 early on to beta test for Terry, my DP is a 4" iCarbon with a full berk street exhaust. Never seen it rev by itself other than when you start it up and it starts at like 1.5k rpm then goes down after a minute.

I will pay closer attention though tomorrow after start up.

[SflBimmer8484]

Run in stock map for a little that way you can filter out the problem.

[Tony135]

Got the same set up as Cooler but I don't experience the problem too much. Definitely not as bad as what you're saying. We should all meet up though! We live within like 5 miles.

[seslait]

Havent had time to check the O2 sensors. I guess, I plan to swap them see if they are backwards. If that doesnt work I'll replace them. If that doesnt work, putting cats back on.

Originally Posted by Gines135

Yeah, the power loss will suck but worrying about stalling out at a stop sign or a light is just ridiculous. I dont even want to go through a drive through because of that. So you haven't heard of any fixes or anything?

[allanak]

I have the same issue. N55 + Stage 2 + BMS DP but I'm 6MT. Only happens when the engine is cold...RPMs fluctuate and has stalled a couple times when stopped at a light if I don't give it some gas. When it gets to operating temp, the idle issue seems to subside. I've been meaning to try and swap my O2 sensors around but haven't got to it quite yet although I don't think they're backwards.

[seslait]

expect the rough idle in cold starts, the price to pay for going catless.

[allanak]

Originally Posted by seslait

expect the rough idle in cold starts, the price to pay for going catless.

To the point of stalling? No, not normal.

Originally Posted by Andrew@ActiveAutowerke

Run in stock map for a little that way you can filter out the problem.

I've tried stock map. Same thing.

[Gines135]

Just tried stock map as well. Same issue. I can start the car and as long as i dont move it then it will idle just fine. Once i put it in reverse or drive and start driving and then hit a stop is when the issues happen. Once my engine temp got warmer the problem goes away. You can still see that its there but its minute and definitely not enough to worry about. The big issue right now is that when its cold and while you're waiting for the car to warm up, it has the possibility of stalling.

I got a suggestion today from that ill try this weekend. Ill let everyone know how that works out.

Wish i had a manual to keep it revved up until it got warm but then again once its warm, dct ftw.

[seslait]

All catless cars sputter when turned on.

[QUOTE=allanak;10944899]To the point of stalling? No, not normal.

[allanak]

Video starts as I'm pulling over. About 14 seconds in, you can hear the rough idle and at 0:17 it stalls. I fire it back up and at 0:35, you see the revs bounce up around until the end of the video.

Don't mind cooler2442's question in the video about how a DCT can stall

[Gines135]

Just drove the car. Was in the 60s outside unlike most of the time lately when im driving wheres its in the 50s or so maybe 40s and it didnt act up at all. Anyone else have similar findings?

[02ws666]

[QUOTE=seslait;10945148]All catless cars sputter when turned on.

Originally Posted by allanak

To the point of stalling? No, not normal.

Not true at all my cam only ls1 with straight pipes runs amazing. All these weird issues make me not even wanna touch my 2012...

Quick question. Will an aftermarket down pipe cause BMW to void my warranty? I'd think the only thing they could do legally is obviously not cover that part ne more... Thoughts?

[allanak]

I just pulled the following codes from my JB4 this morning: 3106, 28A0, 2C90, 2774

I know that 3106 is cat-efficiency related...ok, expected. I think 2C90 is a tuner-related code from the JB. But the others...
2C90 - Blow-off valve, mechanics: Jammed closed - related to lagfix in JB4 I think.
28A0 - Throttle-valve angle - intake-manifold pressure, correlation: Limit value exceeded
2774 - Mass air flow sensor, plausibility: Air mass compared with model too high

edit:
I emailed Terry asking for some input and this was his response:

Those are just the normal 3 tuner codes, and then the catless code.
You can't swap o2 sensors on an N55. Log looks normal where it stalls.
The N55 is just really finicky on cold idle, not much you can do about
it. As a test you could put connector #3, maf sensor, back to stock
leaving rest connected to see if that helps/hurts.

I'll try this tomorrow night as I haven't had time to let the car sit for a cold start since his suggestion.

[Tony135]

I'd just write this off as a normal problem. Unless it some how gives you more of an issue, I'd just leave it alone.

[TEAM SLO]

I have an N55 wit AR Design downpipe, no issues at all with start up on cold or hot engine. No tune and everything else is stock.

No issues either whether the exhaust solenoid line is pinched or not.

[xcluziv33]

I dont have a dp and My revs bounce up and down too. Once every few weeks i stall too, I guess thats just how they are....

[RWolf10]

i get this same issue when i cold start. stalled twice in 5 minutes, once when pulling out of the driveway in reverse to drive, then once at a stop light when accelerating from a dead stop. it was definitely dangerous at the intersection because we have to press on the brake to restart the engine.....lame