Engine stumbling on cold acceleration

J

javis20

Active member
 Hershey, PA USA
Car is a 2011 BMW Z4 50,000 miles. Car stumble on acceleration when cold and has a periodic miss when idling. When the engine is fully warmed up the problem pretty much disappears.

I'm getting the attached codes;

looks like they are pointing to the eccentric shaft sensor...
 

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Engine is 3.0i N52

I'm going to check to see if there are any oil leaks inside the eccentric shaft sensor plug area tomorrow morning.
 
Well looks like the eccentric shaft sensor is leaking..
Maybe I'll do a tutorial..
 

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Yep, oil on there is not good. Happens a lot on the 2.0 E85, but quite rare on the N52. Tutorial would be great 👍
 
Replaced the eccentric shaft sensor and reset the fault codes. Took several test drives and no more fault codes.
However, my problem remains. Still stumbling/hesitating on heavy acceleration. Much worse when cold.

Btw, eccentric shaft sensor and valve cover gasket was a piece of cake on the z4 3.0 n52.
 
javis20 said:
Replaced the eccentric shaft sensor and reset the fault codes. Took several test drives and no more fault codes.
However, my problem remains. Still stumbling/hesitating on heavy acceleration. Much worse when cold.

Btw, eccentric shaft sensor and valve cover gasket was a piece of cake on the z4 3.0 n52.
Click to expand...

How much was the sensor out of interest? I know they used to be expensive :o
Rob
 
I used the VDO. It was $186 from fcpeuro. The job was very easy. Simply remove the one strut tower brace. Disconnect the ignition wire harness, and remove the plug assy from the injectors (leave injectors in place).

I just ordered a few coil packs from Rockauto. I'll start swapping them in and out when the parts arrive. Strongly suspect it's a weak coil pack. Unfortunately it doesn't trow a code. No easy way to find the problem...
 
Don’t want to state the obvious but assume your spark plugs are all good? Typical symptoms of bad plugs is stuttering on hard acceleration.
 
To be honest, I have not. There is only 50k miles on the car. I assume the factory plug is the 4 ground NGK or Bosch. I had those plugs in my VW and they lasted 100k miles. I'll pull a few later and have a look. If I replace them, I'll go with ngk 95712 plugs. I had a problem in the past where the center electrode, on the 4 ground plug, fell into my cylinder. It was fun getting it out...
 
Double checked the plugs. Gaps wore open to a tad over .050. Apparently the service interval is 60k miles for the plugs, so I guess I will just order a set, since it need to be done anyway.
 
javis20 said:
Double checked the plugs. Gaps wore open to a tad over .050. Apparently the service interval is 60k miles for the plugs, so I guess I will just order a set, since it need to be done anyway.
Click to expand...

Well that will be interesting..jury’s out?
 
There is no way I would leave plugs until 60k miles, they are way past their best a long time before that in my experience.

Replaced the ones on my 3.0Si with single electrode iridium ones. Great plugs.
 
javis20 said:
It was the plugs. New eccentric sensor and plugs. Cars running like new again.
Click to expand...

mines just hit 50k, driving fine but curious about getting the sparks done, being pro-active.
 
javis20 said:
I used the VDO. It was $186 from fcpeuro. The job was very easy. Simply remove the one strut tower brace. Disconnect the ignition wire harness, and remove the plug assy from the injectors (leave injectors in place).

I just ordered a few coil packs from Rockauto. I'll start swapping them in and out when the parts arrive. Strongly suspect it's a weak coil pack. Unfortunately it doesn't trow a code. No easy way to find the problem...
Click to expand...

As said,elsewhere, it could be worn plugs,
But check the coil packs,as you mentioned. Mine was doing same for a while and new plugs at that time didn't cure it, but new coil packs did(3 of 6 of mine were done).
Check to see if the gold tips are visible in the coils,and if not,then replace. Although mines an e85,I am sure they are pretty standard, Bosch items.
Hope that helps.

Edit,should have read rest of thread,lol.
Glad you got it fixed :thumbsup:
 
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