[2GDSM1997]

Just recently purchased a 2011 335i (n55), currently going through and fixing the previous owners mistakes. Cars throwing these codes and I’m trying to diagnose it. On cold startups car almost dies after starting. It revs up to 1000-1100 on startup then drops to about 400-300 rpm. While driving when putting the car into neutral (6MT) car will drop all the way down to 400-300 rpm, jump back up to 1000, drop again, then raise back to a normal idle. (Logs of coming to a stop in neutral show a drop in mean rail pressure). I also have some CRAZY timing corrections (see screenshots of log). I have replaced the rail pressure sensor. Any clue what could be happening? I don’t want to just throw a hpfp at it without making sure that’s the issue. I also found these wires spliced and taped up in the fuse box under the hood. I believe it’s for jb4. Could that be causing an issue and if so what do I do with the wires ? Any help/diagnostic advice/input, anything would be helpful !

[konstat]

Originally Posted by 2GDSM1997

Just recently purchased a 2011 335i (n55), currently going through and fixing the previous owners mistakes. Cars throwing these codes and I’m trying to diagnose it. On cold startups car almost dies after starting. It revs up to 1000-1100 on startup then drops to about 400-300 rpm. While driving when putting the car into neutral (6MT) car will drop all the way down to 400-300 rpm, jump back up to 1000, drop again, then raise back to a normal idle. (Logs of coming to a stop in neutral show a drop in mean rail pressure). I also have some CRAZY timing corrections (see screenshots of log). I have replaced the rail pressure sensor. Any clue what could be happening? I don’t want to just throw a hpfp at it without making sure that’s the issue. I also found these wires spliced and taped up in the fuse box under the hood. I believe it’s for jb4. Could that be causing an issue and if so what do I do with the wires ? Any help/diagnostic advice/input, anything would be helpful !

What does your low fuel pressure look like at idle? A high pressure of 650psi at idle is normal (in my N54 at least).

Your AFR is definitely lean like that code is suggesting. Are your O2 sensors maybe junk? However, that wiring job in the ECU also looks sketchy, that could be the cause of your issues. Your 3847 code mean bus error, i.e., CANBus which is what automotive electrical architecture is based on and I bet is because of that junk wiring/splice job. Are confident doing a proper splice? i'd look some procedures up on youtube of a general electrical splice. There are also splice clips available at home depot that you could try to at least see if that's your problem.

[2GDSM1997]

Originally Posted by konstat

What does your low fuel pressure look like at idle? A high pressure of 650psi at idle is normal (in my N54 at least).

Your AFR is definitely lean like that code is suggesting. Are your O2 sensors maybe junk? However, that wiring job in the ECU also looks sketchy, that could be the cause of your issues. Your 3847 code mean bus error, i.e., CANBus which is what automotive electrical architecture is based on and I bet is because of that junk wiring/splice job. Are confident doing a proper splice? i'd look some procedures up on youtube of a general electrical splice. There are also splice clips available at home depot that you could try to at least see if that's your problem.

Low pressure is sitting steady at 87 psi, high pressure minimum for n55 on alldata says 725psi. To the best of my knowledge the O2 sensors aren’t bad. I’ll do my best to splice the wires today and see if it fixes the issues (have a feeling it won’t but won’t hurt to try). Lowest I’ve seen high fuel pressure drop to was 480 psi. I’m also getting this 6293 Code for Current too high. But the fuel pump is at 9 volts.

[konstat]

Originally Posted by 2GDSM1997

Low pressure is sitting steady at 87 psi, high pressure minimum for n55 on alldata says 725psi. To the best of my knowledge the O2 sensors aren’t bad. I’ll do my best to splice the wires today and see if it fixes the issues (have a feeling it won’t but won’t hurt to try). Lowest I’ve seen high fuel pressure drop to was 480 psi. I’m also getting this 6293 Code for Current too high. But the fuel pump is at 9 volts.

Fix that splice and see where that gets you. If it doesn’t help maybe you’d need a new EKP module but also take a look at fuel trims can you log STFT. Also what tune are you running on the car and does it match your fuel

[2GDSM1997]

Originally Posted by konstat

Fix that splice and see where that gets you. If it doesn’t help maybe you’d need a new EKP module but also take a look at fuel trims can you log STFT. Also what tune are you running on the car and does it match your fuel

Alright update time, I spliced the wires (see photo), seems weird that I have two same colors on one side and only one recieving on the other end, hopefully someone can give me some insight to if I spliced it correctly or not 😂 also during the fuel and rpm drop the STFT is at 0%(see picture), the car is FBO with an upgraded intercooler, charge pipe, and downpipe. It’s running on MHD Stage 2+ 91 Tune, I also add about 2-3 gallons of e85 every fill up. 2BEA and 2C42 are gone after splicing the wires, codes 3847, 2BDE, and 2BF0 are still on.

[konstat]

Originally Posted by 2GDSM1997

Alright update time, I spliced the wires (see photo), seems weird that I have two same colors on one side and only one recieving on the other end, hopefully someone can give me some insight to if I spliced it correctly or not 😂 also during the fuel and rpm drop the STFT is at 0%(see picture), the car is FBO with an upgraded intercooler, charge pipe, and downpipe. It’s running on MHD Stage 2+ 91 Tune, I also add about 2-3 gallons of e85 every fill up. 2BEA and 2C42 are gone after splicing the wires, codes 3847, 2BDE, and 2BF0 are still on.

If it holds up to a little pull test then send it. As to why there are 2 wires going into 1, you could try to find an ECU wiring diagram or an N55 at a junk yard and see what that looks like.

I could be wrong but I think those timing parameters you’re looking arent timing corrections, is there a parameter called timing corrections? That’s what is called in the N54 at least.

I run ethanol on the stage 2+ tune as well but you should use fuel injector cleaner or run a tank of pure pump gas every 5 consecutive tanks of ethanol.

Are you able to upload the log on datazap. And possibly a new one (the two logs you sent look the same) I’m wondering if you don’t have a lean condition anymore after splicing since the code went away.

Otherwise, your rail pressure seems fine. I feel like something else is causing your throttle issues at idle. What’s your manifold pressure look like when that happens