[Potatohead-M2]

Anyone else get this sometimes?

Only happens in Sport+ engine map, trans in the third setting and MDM mode on, and typically coming out of a corner, say in second gear and then giving it a good amount (but not full) of throttle. The whole vehicle bucks like a bull.

Unsure if something is wrong or it's just my driving style and I need to adapt. My previous car (RS3) I could easily go like 1/2 - 3/4 throttle halfway through a turn and it would just power on out. Maybe with this vehicle I need to be more patient and smooth with power delivery.

Was reading some similar F80 threads where a bunch of guys were having the same problem. Someone even suggested it could be from the foot backing off the throttle under heavy accel, and then back on when slowing, etc etc, which could be happening I suppose.

[Th3Walrus]

Nope, what octane are you using? Our Canadian gas is known to be 2 points low. I only fill with 93/94, which is recommended anyways.

[Potatohead-M2]

Originally Posted by Th3Walrus

Nope, what octane are you using? Our Canadian gas is known to be 2 points low. I only fill with 93/94, which is recommended anyways.

93-94. I don't believe it is an engine misfire issue, although coincidentally I was planning on doing plugs this weekend anyway.

[cardtables]

By bucking, do you mean the revs go up and down real quick? If so - I have that “problem” sometimes.

[YolkyPalky]

I remember this was a common reported occurrence in the e46 M3, until drivers collectively learned to properly modulate the throttle. I think it’s absolutely a driver error, or at least a driver-caused condition. These engines don’t like weak-tepid-timid throttles, especially in higher response settings. You’ll learn how to feather throttle properly and it’ll go away.

[foxdie262]

The throttle curve is super sensitive in Sport+. It's likely your own foot bucking off of the pedal and back on. I've had it happen.

[Jnat]

I def have this and it's like your foot is slightly modulating on the accelerator. I'd say light and heavy throttle don't do this, it's under medium to about 70 percent throttle and back and forth, hard to explain but def there and can be described as bucking. It is DEF not an engine miss, it's def accelerator / throttle related.

[Potatohead-M2]

Originally Posted by Jnat

I def have this and it's like your foot is slightly modulating on the accelerator. I'd say light and heavy throttle don't do this, it's under medium to about 70 percent throttle and back and forth, hard to explain but def there and can be described as bucking. It is DEF not an engine miss, it's def accelerator / throttle related.

I think you guys are bang on and it’s me likely causing it. If someone asked me when it’s happening I would have said 70% throttle. It seems hitting a bump makes it worse too because it moves your leg and foot and starts it off.

I actually have a medical condition which makes fine movements with my legs and feet a little difficult. This is why I moved into an SUV in the first place. So it’s probably me. I will try and avoid those situations.

[Jnat]

Originally Posted by Potatohead-M2

I think you guys are bang on and it’s me likely causing it. If someone asked me when it’s happening I would have said 70% throttle. It seems hitting a bump makes it worse too because it moves your leg and foot and starts it off.

I actually have a medical condition which makes fine movements with my legs and feet a little difficult. This is why I moved into an SUV in the first place. So it’s probably me. I will try and avoid those situations.

I feel it's def pedal/throttle position related but can't seem to regulate it with my foot under this exact scenario. All in there's no feeling of this, light acceleration same, it's fine. I'm not sure, I guess it's a characteristic of the vehicle, one of the very few negatives. I guess my only question left is i'm tuned on MHD and most of us are running a tune. Is anyone here not tuned and experiencing this?

[Kevin_The_Clean1]

I've experienced this very same thing. Especially when the car is cold & I'm in Sports + mode. Any small bump in the road will easily cause my foot to pulse over the gas pedal & the sharper throttle response / tip in from being in the hyper sensitive Sports + mode will cause this unwanted modulation. The good news is, there's nothing wrong with your X3 M. We simply have to be a little more careful in this particular mode.

[knali8]

Not sure where I watched it but on track I recall seeing one of the drivers using sports mode as opposed to sports+ due to the smoother power delivery.

I definitely agree with this especially in mdm mode.

[Potatohead-M2]

Originally Posted by knali8

Not sure where I watched it but on track I recall seeing one of the drivers using sports mode as opposed to sports+ due to the smoother power delivery.

I definitely agree with this especially in mdm mode.

I wish the engine and exhaust modes were de-coupled like they were in my Audi.

Oh well, no big deal. I tend to agree that regular sport setting is probably better for modulation.

[DBU]

It could be one of the "nanny-systems" kicking in (applying brake or reducing power if you are close to the edge). Try and drive with everything disabled - but be careful...

[Jnat]

Originally Posted by DBU

It could be one of the "nanny-systems" kicking in (applying brake or reducing power if you are close to the edge). Try and drive with everything disabled - but be careful...

100% everything disabled and also, it's not at 100% throttle, it's more like 70%ish so really don't think and or feel it's a nanny like brake. It's like your going on and off the throttle but you're trying your best not to, weird.

[Oldgixxer]

I've had this happen to me a few times. Was 100% driver error as I was leaving the gym after a good quad workout and my legs were a bit shaky. Vehicle started bucking when I was leaving a traffic light turning left and realized it was my leg trembling ever so slightly

[knali8]

Originally Posted by Jnat

100% everything disabled and also, it's not at 100% throttle, it's more like 70%ish so really don't think and or feel it's a nanny like brake. It's like your going on and off the throttle but you're trying your best not to, weird.

Also, Straightpipes - youtube (8:55) that mentioned when they were driving the x4m, when you let off the accelerator, the car applies quite a bit of engine braking - deactivating some cylinders to stop the torque.

[BlownLSX]

Don’t drive at 70% throttle in the upper rpms….very simple solution. Grow a pair and keep it held to the floor until you come up to a turn apply brakes then ramp back in throttle. Your not maintaining speed at 70% throttle, you are still accelerating. Sounds like some autocross is needed to learn the vehicle.

[Potatohead-M2]

Originally Posted by BlownLSX

Don’t drive at 70% throttle in the upper rpms….very simple solution. Grow a pair and keep it held to the floor until you come up to a turn apply brakes then ramp back in throttle. Your not maintaining speed at 70% throttle, you are still accelerating. Sounds like some autocross is needed to learn the vehicle.

Not in upper rev range. 2.5-4k range exiting a corner is when it tends to happen for me.

[BlownLSX]

Originally Posted by Potatohead-M2

Not in upper rev range. 2.5-4k range exiting a corner is when it tends to happen for me.

You are far too low in the rpm if you are exiting a corner. When was the last time you put plugs in? Gapped correctly?

[Potatohead-M2]

Originally Posted by BlownLSX

You are far too low in the rpm if you are exiting a corner. When was the last time you put plugs in? Gapped correctly?

We're talking about street driving here. Second gear turns at that speed/revs are common.

I changed plugs on the weekend just by coincidence but the ones in there were less than two years old, gap was still .031". As has been discussed in this thread already it is not an engine/misfire issue.

[BlownLSX]

Originally Posted by Potatohead-M2

We're talking about street driving here. Second gear turns at that speed/revs are common.

I changed plugs on the weekend just by coincidence but the ones in there were less than two years old, gap was still .031". As has been discussed in this thread already it is not an engine/misfire issue.

Not at 70% throttle they arnt.

[Jnat]

Originally Posted by BlownLSX

Don’t drive at 70% throttle in the upper rpms….very simple solution. Grow a pair and keep it held to the floor until you come up to a turn apply brakes then ramp back in throttle. Your not maintaining speed at 70% throttle, you are still accelerating. Sounds like some autocross is needed to learn the vehicle.

Appreciate your attempt at feedback here but what you're describing is not what i'm talking about. It's on acceleration under power basically through the rpm range and it's an oscillation. Grow a pair, really? I don't drive at 100% throttle all the time so this is not constructive but thanks.