2012 xdrive50i rough acceleration

[svt1998gt]

Guys,

I took the car to the shop to get some work done, but the shop could not figure out why the car has a jerking acceleration. They hooked the computer to it but couldnt find any codes. I dont think its a motor mount issue but you never know, it seems as if the jerk happens when shifting but after its in gear you feel it all the way up. It started off subtle and then had gotten more noticable.

I have replaced all coils and plugs and the issue still persists, just seeing if anyone has had this issue or know where else I can look.

[JoeyBimX5din]

Fuel injector?
Transfer case?

These trucks have a lot of power, have you tried to duplicate the concern with the traction control off, maybe its wheel spin being combated by the traction system, and it translates to you as a jerking acceleration.

Are all your tires the same tread thickness, they could cause a jerky feel with AWD.

[svt1998gt]

Yes tires are all the same, and i am not peeling out and dont know if i could with AWD, i am not even stomping on the accelerator just when i drive normal i feel it and when its in gear it doesnt go away. If injectors that would have thrown a check engine light or code right?

I will try disabling the traction control and check.

Thanks for your help

[svt1998gt]

Traction control didnt make any difference.

[bmwx5er]

If you’re over 50k miles, try a transmission fluid change, transfer case oil change and a corresponding reset of their control units.

[Deftronix]

Unplug the connector to the transfer case and try. It's never truly disabled until the connector is pulled underneath the car. If the problem goes away you know where the issue lies. The TC also has a plastic servo actuator gear that gets stripped out but usually will cause jerkiness during a turn. I second the transfer case + adaptions reset, and/or transmission oil + adaptions reset. Any jerkiness or resistance when you let off the accelerator (does the car coast normally)?

[svt1998gt]

Thanks, i will give those a shot, ill try to find a DIY on the oil changes if they have them.

[svt1998gt]

When i coast the car feels fine, when i am not accelerating and maintaining speed it is also fine. Just when i need the engine to pull is when i experience it.

[mirob]

Originally Posted by svt1998gt

When i coast the car feels fine, when i am not accelerating and maintaining speed it is also fine. Just when i need the engine to pull is when i experience it.

How's your idle? Any spikes/dips in RPM when not in motion?

From what you're describing, it's either your injector(s) or a vacuum/vent line leak. They have very similar symptoms. Matter of fact, a vacuum leak can cause misfire codes.

Look for any black soot on your bumper around the tailpipes, that can be a dead giveaway for faulty injector(s).

Look for any oil around the vacuum/vent lines/pipes. It can be very obvious when they crack but usually it's not. There will be a thin coat of oil where they are leaking.

Also, when my injectors were on their way out, the vehicle didn't throw any codes right away. It usually took a few of days for it to show a CEL and register fault codes.

[JoeyBimX5din]

Lets start with the transmission and transfer case checks, the TC is the weakest link in these trucks, it may lie there. IMHO

[svt1998gt]

Originally Posted by mirob

How's your idle? Any spikes/dips in RPM when not in motion?

From what you're describing, it's either your injector(s) or a vacuum/vent line leak. They have very similar symptoms. Matter of fact, a vacuum leak can cause misfire codes.

Look for any black soot on your bumper around the tailpipes, that can be a dead giveaway for faulty injector(s).

Look for any oil around the vacuum/vent lines/pipes. It can be very obvious when they crack but usually it's not. There will be a thin coat of oil where they are leaking.

Also, when my injectors were on their way out, the vehicle didn't throw any codes right away. It usually took a few of days for it to show a CEL and register fault codes.

No issues with idle, fires up just fine when its cold and sits fine at the light. As far as black soot couldnt that be from the oil i burn as well? I appreciate the advice.

[mirob]

Originally Posted by svt1998gt

No issues with idle, fires up just fine when its cold and sits fine at the light. As far as black soot couldnt that be from the oil i burn as well? I appreciate the advice.

Hmmm, the soot is usually from unburned fuel but I suppose it could be oil as well. Even though BMWs are notorious for burning oil it shouldn't burn that much oil. Guys with bad valve seals usually just burn a ton of oil and blow a lot of smoke, they don't usually experience what you described. Have you ever checked to see what index your injectors are?

If all that checks out, and the vehicle does not register any fault codes eventually, JoeyBimX5din could be on to something.

Worst case scenario, your transmission is slipping or a bad torque converter.

Any way you can record what you're experiencing and post a YT link?

[svt1998gt]

Originally Posted by mirob

Hmmm, the soot is usually from unburned fuel but I suppose it could be oil as well. Even though BMWs are notorious for burning oil it shouldn't burn that much oil. Guys with bad valve seals usually just burn a ton of oil and blow a lot of smoke, they don't usually experience what you described. Have you ever checked to see what index your injectors are?

If all that checks out, and the vehicle does not register any fault codes eventually, JoeyBimX5din could be on to something.

Worst case scenario, your transmission is slipping or a bad torque converter.

Any way you can record what you're experiencing and post a YT link?

I will give it a shot, its more of a sitting in the car and driving, but i will shoot a video tomorrow and send a link over.

[mirob]

Originally Posted by svt1998gt

I will give it a shot, its more of a sitting in the car and driving, but i will shoot a video tomorrow and send a link over.

Didn't think of this yesterday but could it be that your fuel pump (HPFP) is starting to give out slowly? It's possible that the vehicle is running rough at higher RPMs if it's not getting the fuel it needs. When the N54 guys had issues with these, eventually the cars wouldn't even start.

[svt1998gt]

Originally Posted by mirob

Didn't think of this yesterday but could it be that your fuel pump (HPFP) is starting to give out slowly? It's possible that the vehicle is running rough at higher RPMs if it's not getting the fuel it needs. When the N54 guys had issues with these, eventually the cars wouldn't even start.

That is what i was thinking also, i also have an n54 mine was leaking and had the gas smell before it went out, i might consider that because nothing seems to add up. I did get the cable is there a software I can run and log A/F ratio to confirm?

Thanks for the help guys!

[mirob]

Originally Posted by svt1998gt

That is what i was thinking also, i also have an n54 mine was leaking and had the gas smell before it went out, i might consider that because nothing seems to add up. I did get the cable is there a software I can run and log A/F ratio to confirm?

Thanks for the help guys!

I believe M5James has been logging data even before he had JB4 but I'm not sure what app/software he is/was using...maybe Torque Pro? I had the app but I never used it for logging but I think I remember seeing the option to do so.

I don't know how to tag names on threads so try to PM him directly.

[RustyX5M]

Subscribed.

I've been having (what I believe is) the same issue for quite some time. Eventually I got tired of dumping $ into it and people telling me I'm crazy, so have just been living with it.

Mine is most noticble in "M" mode with manual or S shift. There's a noticeable and delayed kick when on and off throttle. I've done throttle adaption/reset and had a full software update, though still persists.

I'll be interested to hear what your symptoms boil down to.

[docdox]

I had the same problem. Replaced the spark plugs and coil packs and now it RIPS!!

[svt1998gt]

Originally Posted by docdox

I had the same problem. Replaced the spark plugs and coil packs and now it RIPS!!

Thanks i already did that, no bueno.

[svt1998gt]

Originally Posted by RustyX5M

Subscribed.

I've been having (what I believe is) the same issue for quite some time. Eventually I got tired of dumping $ into it and people telling me I'm crazy, so have just been living with it.

Mine is most noticble in "M" mode with manual or S shift. There's a noticeable and delayed kick when on and off throttle. I've done throttle adaption/reset and had a full software update, though still persists.

I'll be interested to hear what your symptoms boil down to.

I havent had any time to take it to the shop but will prioritize it next week sometime and report back on what the other shop finds.

[mirob]

Originally Posted by svt1998gt

I havent had any time to take it to the shop but will prioritize it next week sometime and report back on what the other shop finds.

Any updates?

[BlackX5]

Sounds like something electrical to me. Particularly if the engine is essentially cutting out and causing the jerking. I had the same problem once (not a bmw). The engine was jerking because I had a starter wire that was touching an exhaust pipe and it melted the insulation and it grounded out the entire electrical system causing the engine to jerk.. Eventually the wire caught on fire. That was really fun. By the way, if only 1 cylinder is loosing its spark, then it will cause a slight miss and you will feel it a little, but It wont really jerk like "all cylinders" are deficient and basically Not Pulling at all. That would be a larger problem, like the whole electrical system is being shorted out or not supllying enough current for spark. If the jerking is really large then you would have to suspect that it was not only 1 cylinder that was failing to fire. instead it would be more likely that all cylinders are not firing. And if all cylinders are intermittently not firing, then changing all the coils would not help. Because each coil only serves 1 cylinder and the likelihood of all coils going bad simultaneously would be like the odds of getting struck by lightning or winning the lotto.
When you put the engine under a load, more spark is required. It might be whatever device that feeds the coils, and I do not know what that it because I do not have the diagrams.. or it might be something as simple as a sensor that is misinterpreting where you are in the throttle and subsequently is not boosting the spark.

It does not sound like a fuel problem to me. Fuel pumps pressurize the entire system to a peak value. If your engine was being starved of fuel at only under a load but idles fine, then I think you would just have a loss of performance, but no jerking. And it would not really run lean because the 02 sensors would try to keep the mixture at 14.7:1 like it is programmed to do. So, if you reduce fuel, then it would compensate by having less performance, but no jerking.

good luck