[kwazmo@gmail.com]

Hey everyone,

first post so forgive me if this isn't posted in the correct place, feel free to move it if so.

I have a 2012 328i, f30 body, n20 motor, 130xxx miles. I have recently (within the past month) installed an injen intake, a vrsf 5" intercooler, and tuned with stage 1 bootmod, fueled with Arizona 91. i have a catless downpipe on order, but stock as of right now.

I am experiencing somewhat of a studder during acceleration at higher RMPs. From what I can tell so far, it's only really presenting when WOT at 3k and up in 3rd 4th 5th. prob 6th too just haven't pushed it that far yet.

Anyways the studder is sharp and sudden, and singular, but happens throughout the pull prob on average 3-4. and seems like its gotten worse the past 3 days.

i was initially thinking fuel starvation? any ideas or other test i could do to diagnose... whatever... is appreciated. TIA

[Kristofer_J]

Hi,

I have a stock 2012 328i with manual transmission (crucial in my case) and I had the same, or similar, error as you.

Under hard acceleration the car studder around 2500-4000 rpm, so at max torque. So maybe not exactly the same behavior as you car.

The problem in my case was a worn down middle crank shaft bearing. Worn down in the sense that the whole crank shaft moved in the axial direction. According the repair shop this happened on early n20 cars with manual transmission due to axial loads created by the clutch separating. The middle bearing is the only bearing that takes axial load. The bearing design on these early models were bad and changed later to a design more suited for axial load (according to the repair shop). The solution was to change the middle bearing, a very expensive repair…

The reason for the stuttering was that because the craft shaft moved axially the clutch engaged at high loads causing the clutch to slip. Needless to say I also had to change the clutch, it was reduced to dust.

[MaverickCruise]

Why not try 93?