[mgorman87]

Hello,

I recently purchased a 2011 328i with 78,000 miles on it.

Up until just a few days ago, the car has been working fine. I was able to really ride it hard and it was having no issues. I don't drive like that all the time. Just when I need to (and sometimes for fun).

So far, all I've done to the car is some coding.


The other day, I started noticing this intermittent shuddering coming from the front of the car during acceleration. I could feel it in my foot as well.

It seems to happen when the car is in lower RPM (2000-3000RPM) and if I'm already accelerating and push the gas down more.

Never owning a BMW before, I'm not quite sure what it is.

The best way I can describe it is that it feels like the clutch or flywheel is slipping and the teeth aren't grabbing. Sometimes, the shuddering is accompanied by a burning smell, but not a clutch burning smell.

It doesn't happen every time. I am still able to accelerate pretty hard and the car goes and shifts and is happy. I am a little hesitant to really punch it hard from low RPM to see what happens. That slipping makes me cringe when it happens.

I just purchased the used car warranty today, but there is a 30 day/1000 mile or 90 day/ 200 mile waiting period. I don't drive my car enough to hit 1,000 miles within 30 days, so it looks like I am going to have to wait at least a couple months before I can be covered.

I stopped by the dealership today and they recommended waiting until I had warranty coverage to take the car in.

I'm hoping it's an easy fix and not costly.

I am somewhat mechanically inclined, so changing fluids, plugs, etc. isn't out of the question for me.

Any feedback or troubleshooting I could do is greatly appreciated.


EDIT: I went out and drove it some more to see if I could figure out when it happens. From what I can tell, the issue is occurring when I'm already driving and I push the gas down, which makes the car want to shift gears. It's during this shift that I feel the shudder. If I don't let off the gas, it "catches" after a second or two and it continues accelerating. I also tried from a full stop and accelerated hard and it shuddered (not wheel slip) and then once it "catches" it was smooth. I have no issue doing moderate acceleration and it flies through the gears like it should. It's only when it's trying to change gears from low RPM.

It was suggested by my neighbor to put some Lucas oil in there since it's thicker?

I am also reading posts about replacing solenoids? To me, this really feels like the trans is not grabbing the fly wheel, which is causing it to slip.

[Spitfire007]

Had the same problem. Cured it.

It's a basic misfire, but it's not bad enough to set off a check engine light.

Change your spark plugs. You'll probably see one is burnt out more than the others. If it persists, change out your coils too.
YES DO ALL COILS. it's cheap and piece of mind.

[mgorman87]

Originally Posted by Spitfire007

Had the same problem. Cured it.

It's a basic misfire, but it's not bad enough to set off a check engine light.

Change your spark plugs. You'll probably see one is burnt out more than the others. If it persists, change out your coils too.
YES DO ALL COILS. it's cheap and piece of mind.

So a misfire manifests as shuddering? It really feels like the trans is slipping. It would make sense though that it's a misfire since it only happens under heavy load.

Would it make sense just to do both spark plugs and coils at the same time? or is doing coils unnecessary if they don't need changing?

[Spitfire007]

Originally Posted by mgorman87

So a misfire manifests as shuddering? It really feels like the trans is slipping. It would make sense though that it's a misfire since it only happens under heavy load.

Would it make sense just to do both spark plugs and coils at the same time? or is doing coils unnecessary if they don't need changing?

Yep. Started at the same mileage as you.

At low rpm in a higher gear (car is a manual), say 30 mph in 4th, i would punch it and the whole car would lurch until the rpms got above 2500 or so. Then smooth.

I changed out both plugs and coils, as I didn't feel like having to chase down a misfire 20000 miles later. It was only an extra $120 for Delphi coils.
Coils may not be necessary, but I wanted piece of mind and the most up to date part, and I drive the car hard.

Oembimmerparts.com

Been solid ever since.

[mgorman87]

Originally Posted by Spitfire007

Yep. Started at the same mileage as you.

At low rpm in a higher gear (car is a manual), say 30 mph in 4th, i would punch it and the whole car would lurch until the rpms got above 2500 or so. Then smooth.

I changed out both plugs and coils, as I didn't feel like having to chase down a misfire 20000 miles later. It was only an extra $120 for Delphi coils.
Coils may not be necessary, but I wanted piece of mind and the most up to date part, and I drive the car hard.

Oembimmerparts.com

Been solid ever since.

Great. Thanks! I'm somewhat relieved that it isn't a tranny issue.

I've got the plugs arriving tomorrow. Didn't order the coils just yet. I want to see what kind of difference new plugs will make.

This probably explains the rough idle at cold start. Seems to take some time to find it's resting spot on the tach.

[Spitfire007]

That rough idle could also be a slight vacuum leak. Common on BMWs.

Hopefully I'm right and it's just spark plugs....

[mgorman87]

Originally Posted by Spitfire007

That rough idle could also be a slight vacuum leak. Common on BMWs.

Hopefully I'm right and it's just spark plugs....

Replaced the plugs. Fairly straight forward. Car purrs like a kitten now! Thanks again!