[tmurphy31a]

Hello all.

I have attempted to find other posts specific to my problem but unable. Here are the details:

2015 335xi M-Performance
Manual Transmission
53000 km (33k miles)
No Mods
Shell fuel 91 octane

Recently began noticing during hard acceleration only I get a stutter/hesitation/brief loss of power.

This occurs in any gear and happens roughly at 2200 and 3200 RPM. RPM's briefly drop (power loss) but increase within 1-3 seconds (power gain), with a slight shutter. If I continue accelerating hard in the same gear this issue occurs again in the 3000 RPM range. I can continue accelerating without any issues past that point.

If I don't hard accelerate I don't notice the problem at all.

Spark plugs replaced.
Software updated.

Thanks for any input!
Tim

[n55david]

Originally Posted by tmurphy31a

Hello all.

I have attempted to find other posts specific to my problem but unable. Here are the details:

2015 335xi M-Performance
Manual Transmission
53000 km (33k miles)
No Mods
Shell fuel 91 octane

Recently began noticing during hard acceleration only I get a stutter/hesitation/brief loss of power.

This occurs in any gear and happens roughly at 2200 and 3200 RPM. RPM's briefly drop (power loss) but increase within 1-3 seconds (power gain), with a slight shutter. If I continue accelerating hard in the same gear this issue occurs again in the 3000 RPM range. I can continue accelerating without any issues past that point.

If I don't hard accelerate I don't notice the problem at all.

Spark plugs replaced.
Software updated.

Thanks for any input!
Tim

the normal go to are plugs then coils but honestly it's a guessing game beyond proper diagnostics. it's low miles which is weird. has this been an ongoing issue or just within the last fuel fillup?

[tmurphy31a]

Originally Posted by Phantom10R

the normal go to are plugs then coils but honestly it's a guessing game beyond proper diagnostics. it's low miles which is weird. has this been an ongoing issue or just within the last fuel fillup?

This is an on-going issue.

[n55david]

Originally Posted by tmurphy31a

This is an on-going issue.

no codes? chargepipe not broken or anything weird?

had any work been done on the car prior to this happening even if it doesn't seem related?

[tmurphy31a]

Originally Posted by Phantom10R

no codes? chargepipe not broken or anything weird?

had any work been done on the car prior to this happening even if it doesn't seem related?

Currently no check engine light or indication on dash. No lights at all have popped up.

This problem occurred out of the blue with no contributing factors such as recent work, damage to the vehicle, change in fuel.

I had a couple of friends drive the vehicle and they did not hear any noise from the engine like a hiss or air escaping - which would point to a charge pipe correct?

To help explain the feeling when the problem occurs it feels like a fuel delivery issue - almost like the engine is trying to pull more fuel but not receiving it.

The question I am trying to answer is why would this issue occur only when hard acceleration - could it be a fuel delivery issue, or possibly a turbo? Could there be an issue with the drivetrain? If I am experiencing this issue while in gear would the transmission be a factor?

Thanks

[thejeremyman9]

Originally Posted by tmurphy31a

Currently no check engine light or indication on dash. No lights at all have popped up.

This problem occurred out of the blue with no contributing factors such as recent work, damage to the vehicle, change in fuel.

I had a couple of friends drive the vehicle and they did not hear any noise from the engine like a hiss or air escaping - which would point to a charge pipe correct?

To help explain the feeling when the problem occurs it feels like a fuel delivery issue - almost like the engine is trying to pull more fuel but not receiving it.

The question I am trying to answer is why would this issue occur only when hard acceleration - could it be a fuel delivery issue, or possibly a turbo? Could there be an issue with the drivetrain? If I am experiencing this issue while in gear would the transmission be a factor?

Thanks

Just because you dont have a message on the idrive or CEL doesn't mean they are no codes. You need to do a full scan.

You should also inspect the CP because you don't always hear boost leaks. It has to be a huge leak and you need to be running a lot of boost to hear it. At stock boost levels its very possible for one to be inaudible from inside the car.

[tmurphy31a]

Originally Posted by thejeremyman9

Just because you dont have a message on the idrive or CEL doesn't mean they are no codes. You need to do a full scan.

You should also inspect the CP because you don't always hear boost leaks. It has to be a huge leak and you need to be running a lot of boost to hear it. At stock boost levels its very possible for one to be inaudible from inside the car.

Ok excellent. I will connect to the car and do a scan and let you know.

Thanks.

[redbullfan]

Could be your transfer case taking a shit tbh

[voxumf30]

Originally Posted by tmurphy31a

Hello all.

I have attempted to find other posts specific to my problem but unable. Here are the details:

2015 335xi M-Performance
Manual Transmission
53000 km (33k miles)
No Mods
Shell fuel 91 octane

Recently began noticing during hard acceleration only I get a stutter/hesitation/brief loss of power.

This occurs in any gear and happens roughly at 2200 and 3200 RPM. RPM's briefly drop (power loss) but increase within 1-3 seconds (power gain), with a slight shutter. If I continue accelerating hard in the same gear this issue occurs again in the 3000 RPM range. I can continue accelerating without any issues past that point.

If I don't hard accelerate I don't notice the problem at all.

Spark plugs replaced.
Software updated.

Thanks for any input!
Tim

How filled is your gas tank when you notice the stutter? I've had similar issues of power loss under heavy load / steep hills. It started with fuel cuts, kinda feels like your hitting a wall and then it gets back on it, until you hit the wall again. After it happened multiple times over the course of a year it finally threw a drivetrain malfunction and limp mode. From what I can tell in my case it has to be an issue with fuel delivery, as long as I don't try and hoon around a quarter tank everything is fine.

[n55david]

Originally Posted by voxumf30

How filled is your gas tank when you notice the stutter? I've had similar issues of power loss under heavy load / steep hills. It started with fuel cuts, kinda feels like your hitting a wall and then it gets back on it, until you hit the wall again. After it happened multiple times over the course of a year it finally threw a drivetrain malfunction and limp mode. From what I can tell in my case it has to be an issue with fuel delivery, as long as I don't try and hoon around a quarter tank everything is fine.

does it die at 1/4 tank like it's out of fuel?

[voxumf30]

Originally Posted by Phantom10R

does it die at 1/4 tank like it's out of fuel?

It's never died on me, just runs to empty faster than you would think it should.

[tmurphy31a]

Originally Posted by voxumf30

How filled is your gas tank when you notice the stutter? I've had similar issues of power loss under heavy load / steep hills. It started with fuel cuts, kinda feels like your hitting a wall and then it gets back on it, until you hit the wall again. After it happened multiple times over the course of a year it finally threw a drivetrain malfunction and limp mode. From what I can tell in my case it has to be an issue with fuel delivery, as long as I don't try and hoon around a quarter tank everything is fine.

Hi.

My car just threw the 'Drivetrain Malfunction' code and my issue is happening more regularly, and now at medium+ acceleration.

I am waiting on an OBD reader to check the codes and record parameters.

This occurs with full/half tank of fuel.

Is there an OBD reader you or someone recommends that will allow me to record parameters that I can export and share here?

Thanks for the reply!

[tmurphy31a]

Originally Posted by redbullfan

Could be your transfer case taking a shit tbh

Do you have a recommendation on a way to narrow down to this possible conclusion I can try?

[thejeremyman9]

Originally Posted by tmurphy31a

Hi.

My car just threw the 'Drivetrain Malfunction' code and my issue is happening more regularly, and now at medium+ acceleration.

I am waiting on an OBD reader to check the codes and record parameters.

This occurs with full/half tank of fuel.

Is there an OBD reader you or someone recommends that will allow me to record parameters that I can export and share here?

Thanks for the reply!

Lots of free apps/etc can pull codes.

If you want proper logging capabilities that people are used to, you might need to consider something like MHD's monitoring module. Free apps offer datalogging, but from what ive seen, that usually arent that helpful.

[AndrewC1989]

Originally Posted by tmurphy31a

Do you have a recommendation on a way to narrow down to this possible conclusion I can try?

Disable xDrive and see if the symptoms go away.

https://www.xdelete.app/

[rmik88]

What plugs did you use?

[tmurphy31a]

Originally Posted by rmik88

What plugs did you use?

Dealer installed. I imagine OEM?

[JaredG_F30]

This was happening to me and ended up being a bad fuel injector. Do you have a rough cold start?

[tmurphy31a]

Originally Posted by JaredG_F30

This was happening to me and ended up being a bad fuel injector. Do you have a rough cold start?

Hi Jared.

Not sure what a rough cold start would be - I have not noticed any changes with start up.

However - roughly around the same time as I noticed this issue I started to feel a vibration at idle - almost like exhaust low hum. My seat will have a slight vibration.

I just got my OBD reader so not I have to figure out how to use it - are there parameters specifically you might know to look at?

[thejeremyman9]

Originally Posted by tmurphy31a

Hi Jared.

Not sure what a rough cold start would be - I have not noticed any changes with start up.

However - roughly around the same time as I noticed this issue I started to feel a vibration at idle - almost like exhaust low hum. My seat will have a slight vibration.

I just got my OBD reader so not I have to figure out how to use it - are there parameters specifically you might know to look at?

It's pretty difficult to try and diagnose issues like this purely with datalogs, especially if those datalogs are not collected with something like MHD or BM3. Free logging apps rarely provide what you need.

Hopefully it can at least scan for codes, including shadow codes, and you can go from there. If there's no codes and you cant collect useful data logs you are back to a guessing game or trial and error.

[redbullfan]

Originally Posted by AndrewC1989

Disable xDrive and see if the symptoms go away.

https://www.xdelete.app/

My symptoms were still there with x-Delete. My mechanic told me that the clutches inside the transfer case still bind and will have the same behavior. I just picked up a new transfer case and am getting it installed on Thursday. will update if my issues is gone.

[redbullfan]

Originally Posted by tmurphy31a

Do you have a recommendation on a way to narrow down to this possible conclusion I can try?

So with my car, i felt it stutter and heard a metallic noise. Showed it to my mechanic and he said the transfer case is on its way out. I took his word cause he's dealt with it on plenty of cars mainly f10s, 328i 328d as well as many e9Xs