[ronny214]

I have a 2014 6MT 335xi that has 5500 miles on it, though I noticed this issue at around 500 miles. The car has an upgraded catless down pipe (but the issue has happened before and after install) and has a JB4 installed. I've also installed the BMS oil cooler mod to see if I can't get the engine to run a bit cooler and solve the issue. The issue I'm having:

When in either low or high rev, engine below operating temp and engine at operating temp (ranging from between 160 to the 250 optimal temp mark), when I get on the acceleration there are times when there is no power. The power eventually comes, but it isn't there when I need it. It isn't a jerky power cut or anything like that. It has smooth operation/cylinder firing, just greatly reduced power output. It almost seems like the boost is being cut to like 2 pounds of boost pressure.

In some instances it'll blast through 2nd gear and then a quick shift into 3rd with the pedal buried results in an instant severe reduction in power, even though the pedal is held down. The power is there, and eventually it comes, but it is like a knotchy succession in power increase. It is almost like when I hit the gas someone has a click-knob that with each turn of the knob the power increases a bit more. Eventually, as I climb higher into the revs it might go ahead and all of a sudden give me full power, but most of the time I shift into the next gear and i get full power.

There are also instances where I have been cruising with no heavy demand, and I'll do a gentle downshift into 4th gear and hit the throttle. In these instances when the issue occurs it is like there is half power. I let off the throttle and try again, and there is full power. One example of this was driving down the highway in 6th gear. I dropped it to 4th to fly around a few cars, hit the pedal hard, and the cars speed almost doesn't increase at all. It was as if I was barely pushing the acceleration pedal down.

This doesn't happen every time, but it is a fairly consistent issue. It seems to happen most frequently after a good strong pull through a gear like 1st or 2nd where it gets close to redline. Then after shifting to the next gear and dropping the pedal to the floor, power is reduced. I can let off the gas and then reattempt full throttle, and it'll be immediately back to normal.


Things I'm not seeing:

- No warning on the display (drivetrain malfunction or anything like that)
- No CEL lights
- No half-engine lights
- It doesn't seem like limp mode since it eventually pulls out of it
- No DSC/DTC light(s) coming on to indicate slipping (which would seem unlikely anyways considering I"m typically on a straight stretch and I have AWD)


Car stats:
5500 miles
oil changed at 1000 miles
93 octane fuel (Shell)
ER Downpipe 4" catless
JB4 running map 2 (problem also occurred in map 1)
X-Drive with Sport Package (not M-Sport)
BMS Sport Oil Cooler Valve




Any insight or help would be greatly appreciated.

[mike@x-ph.com]

When engine is below 160 jb4 is disabled thats why you do not have any power.
If the issue is also happening with temp between 160 and 250, post couple logs.

[ronny214]

Originally Posted by mike@x-ph.com

When engine is below 160 jb4 is disabled thats why you do not have any power.
If the issue is also happening with temp between 160 and 250, post couple logs.

Yes, the issue is happening ranging from the minimum 160 all the way up to the optimal operating temp (250). I can try to catch it during a log run, but I still do not suspect the JB4 is the issue as this was doing it before I put the JB4 on.

A BMW Tech that I'm friends with mentioned that it could be the wastegate controller failing. Anyone have any thoughts on that?

[mike@x-ph.com]

Originally Posted by ronny214

Yes, the issue is happening ranging from the minimum 160 all the way up to the optimal operating temp (250). I can try to catch it during a log run, but I still do not suspect the JB4 is the issue as this was doing it before I put the JB4 on.

A BMW Tech that I'm friends with mentioned that it could be the wastegate controller failing. Anyone have any thoughts on that?

Post a log so we can help.

[ronny214]

Originally Posted by mike@x-ph.com

Post a log so we can help.

Okay. I'll try to get one within the next day or two. We have pretty much figured out what we need to do to replicate the issue, so it'll take a couple of runs on the JB4 logging.

[Raikkonen]

ronny, this is crazy because I'm never in this part of the forum (my car's 100% bone stock), but I experienced EXACTLY what you described today on my car, on the same route I drive every day….so I knew something was amiss.

The weird part is that this is the FIRST time I've ever experienced this.

It happened a few times over the course of maybe 5 minutes, 2 miles from my house, right before I got on the expressway. I was on residential streets with traffic lights (light traffic) when it happened, and then it happened on the expressway once more. It was about 70 degrees this morning.

I have a 2013 335i with a 6-spd manual, 9,000 miles, M sport pkg. Only one oil change a couple of months ago at my dealership…no other maintenance, issues, or problems. Car has been rock solid. I'm also an OCD owner, always warm my car up, followed break-in, etc., etc.

I drive 50 miles a day, and the issue didn't repeat itself, so I'm not freaking out yet…came to the site to do a search on the issue, and then randomly found your post…curious to see what you find, but it may not be tune related...

[ronny214]

Originally Posted by Raikkonen

ronny, this is crazy because I'm never in this part of the forum (my car's 100% bone stock), but I experienced EXACTLY what you described today on my car, on the same route I drive every day….so I knew something was amiss.

The weird part is that this is the FIRST time I've ever experienced this.

It happened a few times over the course of maybe 5 minutes, 2 miles from my house, right before I got on the expressway. I was on residential streets with traffic lights (light traffic) when it happened, and then it happened on the expressway once more. It was about 70 degrees this morning.

I have a 2013 335i with a 6-spd manual, 9,000 miles, M sport pkg. Only one oil change a couple of months ago at my dealership…no other maintenance, issues, or problems. Car has been rock solid. I'm also an OCD owner, always warm my car up, followed break-in, etc., etc.

I drive 50 miles a day, and the issue didn't repeat itself, so I'm not freaking out yet…came to the site to do a search on the issue, and then randomly found your post…curious to see what you find, but it may not be tune related...

Do an experiment. Get on a highway and get up to 6th gear and around 55 to 60 mph. Then drop it to 4th, get your revs up near 6000 RPM, and put the pedal down. See if you can repeat what I continually am getting, and what you got those few times. I notice it is when you drop it and hit around 6000 RPM that it does this most often, though I have experienced it in other rev ranges.

[KellerKiller]

Does the sport line have the auxiliary cooling fan that the msport does? It sounds a bit like a problem I had a few times. The OEM cooling fan had some sort of glitch that would cause it to kick on when it wasn't needed and also told the engine it was overheating. Power dropped to almost nil, but would return to normal after restarting the car. They replaced my fan once, didn't fix the problem. BMW made a replacement this year for the part though and after that install, I've had no issues. I don't know if it's the same issue, but with your car throwing no codes, it sounds similar enough to look into.

[ronny214]

We finally got logs for the issue experienced above. I uploaded 9 runs to DataZap and put notes in the description of what was occurring for each log. Also, the logs are named for what the run was. Does anyone see anything that stands out here? Thanks!

Runs 1-3: http://datazap.me/u/ronny214/2014-n5...log=0&data=1-4

Runs 4-6: http://datazap.me/u/ronny214/2014-n5...log=0&data=1-4

Runs 7-9: http://datazap.me/u/ronny214/2014-n5...log=0&data=1-4

[Hernandiaz11]

I'm experiencing the exact same symptoms myself, and they began when I installed the JB4. It's pretty frustrating actually......if I shift quickly from first to second feel a sever delay in acceleration. I've previously owned a tuned B5 S4 and also a 2008 N54 335i with JB4 and I had never felt this before.
I'm not sure if it's because boost is low, or if throttle position is fluctuating between shifts. Either way, I'm guessing it's the JB4 and I'm hoping there will soon be a firmware update/revision that will correct this.

[Hernandiaz11]

Ronny, any updates on this issue? I see you also posted in N54tech and I also commented on that thread. I bet most people have this issues if they try to shift quickly.

[Jerich0]

Yes wanting updates from this as well...

You said problem is NOT present WITHOUT JB4 correct?

[monkeydonot]

I know this is an older post, but this just happened to me today on my stock 2013 Msport 335i auto. Making a left turn on yellow, I hit the gas, and very little power. It would rev, but not go much. No lights on dash, just greatly diminished speed. Dangerous! Pushed the accelerator on and off, and sometimes it would go, others, it would just lag. Taking it to the dealer today, because someone could really get hurt.

[963mw]

Hey, I was experiencing the same exhaust problem with my 435i X-Drive and asked around in the forums about it. Only answer I got is limp mode, google it and you'll see that everyone faces this issue at a point and time

[ShlemonboostedM]

Normal .. Most m sport f30 335i have this issue .. Including me .. and alot of members from here you'll need to restart th engine and it will go away .. Don't bother going to dealers they won't find anything ...

[Hernandiaz11]

Originally Posted by nickhelou

Hey, I was experiencing the same exhaust problem with my 435i X-Drive and asked around in the forums about it. Only answer I got is limp mode, google it and you'll see that everyone faces this issue at a point and time

Originally Posted by ShlemonboostedM

Normal .. Most m sport f30 335i have this issue .. Including me .. and alot of members from here you'll need to restart th engine and it will go away .. Don't bother going to dealers they won't find anything ...

Thanks for the advise guys, but I'm well aware of what limp mode. According to the logs I looked at, this is a temporary misfire due to a very rich condition between shifts along with reduced timing. The "bogging" lasts only 1-2 seconds and it only happens when up-shifting quickly or when requesting WOT at a lower RPM (~2500). I noticed the issue isn't as severe when running 30% E85 on map 5