[petelazro]

Hi guys, so I have been struggling with the following problems for over a year:

Jerky transmission when shifting and rpm fluctuation on start up. up and down 100-200rpm. Then it levels out but the car feels very sluggish when accelerating with intermittent surges of power. the car is a 2008 328xi with 125K KM on it.

I had recommendations to do all sorts of things from air filters, transmission solenoid replacement to tranny fluid/filter replacement, eccentric shaft sensor ect.

I finally did my spark plugs this weekend at 125K (160K is when its called for) and my car is idling perfectly and there is an instant throttle response unlike before. Power is up greatly too! I checked my old spark plug gaps and they were at 0.51-0.55! these were the original bosch plugs(not sure if that is the range for the gaps since the new ngks are 0.43/0.44). The car drives like a different car and to think it was just the spark plug gap. my shifts are very smooth as well. (not sure what plugs have to do with tranny shifts)

Im surprised it didnt throw a code.

Anyways i just wanted to share this experience as i was plagued with this problem for over a year with 3 visits to the dealer and hundreds of dollars thrown at the car. Hope this helps some other people.

[jadnashuanh]

Sometimes, it just comes down to the basics.

I guess it's a tribute to the ignition system that it didn't misfire enough to trigger a fault, but even firing requires consistency between the cyclinders. A lesson to all, thanks.

[petelazro]

this was my first bmw and i found the drive to be just okay before doing the plugs but oh man! this is a new car! I am also happy the car is driving smooth like it should otherwise this would have been my last bmw.

hope this helps people who are as frustrated as i was.

[jetblack328]

Thanks for the helpful info. Can you please let me know the part number of the NGK plug you installed? Thanks.

[petelazro]

NGK LZFR6AP-11GS were the plugs i installed. my friend put them in his 128 and work just the same. after about a week the car runs amazing! oh man! now i know how it feels to drive a bmw! the throttle response is 100000 times better but im more happy that all my jerky transmission issues went away!!!

good luck

[onthe3rdday]

I had the same issue @ 77 thousand miles, the cylinder 1 spark gap was .55 and I was misfiring. The other plugs were in good shape.

[cdgatti]

at what mileage do they recommend doing the plugs on an N52?

[petelazro]

they call for it at 160K km i believe. do them at 80-100K km specially if you have sluggish performance. or at least pull them out and check the gap.

[cdgatti]

this thread caused me to change mine out too! 328i with ~74K miles. Car running ok beforehand alot of the characteristic n52 surging type issues, especially when cold. stock plugs are labeled Bosch BMW R6 and that's all. They all had a gap approx. 0.055. I used the NGK plugs PLZFR6A-11S, which have a gap about 0.043. Car started fine and runs smooth, no error lights. Idle is closer to 700 rpm after it warms up, beforehand it was around 650+ rpm. Not scientific, but the needle seems to have a little less fluctuation. Haven't driven car yet will report back if there is any improvement.

little update: went for about 30 minute drive and it is definitely noticeable. feels just like what it is... the car feels like it had a 'tune-up'. engine revs freer from just off idle, it takes the accelerator pedal with a little less balking when starting from a stop or slow speed maneuvers. I would say the annoying little throttle response issues with the 328i that I had learned to live with are alot reduced, probably more like when the car was new, but I never felt that as I bought the car with 25K miles. I plan on keeping this car to 150K, so glad I replaced the plugs now instead of waiting till 100K.

[Kevingro0478]

Originally Posted by petelazro

Hi guys, so I have been struggling with the following problems for over a year:

Jerky transmission when shifting and rpm fluctuation on start up. up and down 100-200rpm. Then it levels out but the car feels very sluggish when accelerating with intermittent surges of power. the car is a 2008 328xi with 125K KM on it.

I had recommendations to do all sorts of things from air filters, transmission solenoid replacement to tranny fluid/filter replacement, eccentric shaft sensor ect.

I finally did my spark plugs this weekend at 125K (160K is when its called for) and my car is idling perfectly and there is an instant throttle response unlike before. Power is up greatly too! I checked my old spark plug gaps and they were at 0.51-0.55! these were the original bosch plugs(not sure if that is the range for the gaps since the new ngks are 0.43/0.44). The car drives like a different car and to think it was just the spark plug gap. my shifts are very smooth as well. (not sure what plugs have to do with tranny shifts)

Im surprised it didnt throw a code.

Anyways i just wanted to share this experience as i was plagued with this problem for over a year with 3 visits to the dealer and hundreds of dollars thrown at the car. Hope this helps some other people.

I know this is a very old post, but it’s absolutely still relevant. Thank you for sharing on that day in 2014. Welcome to 2025! Hopefully you got the problem figured out lol