[supercharger]

I have a 2009 328i. My car does not accelerate smoothly from a full stop to about 30 mph. The acceleration is staggered. I had the transmission checked and everything was okay. No codes. Can anyone tell me if the uneven acceleration is due to plugs and coils? Would the problem go away if I replaced all the spark plugs and ignition coils? Thanks

[ppointer]

If you have a coil/plug problem, the misfire would throw codes. Apologies for not having those codes at my fingertips. Also, whenever one of our cars suffered a coil problem, the car was basically not driveable, the miss is so bad. I think something else is wrong with your car.

[e91Owner]

Originally Posted by supercharger

I have a 2009 328i. My car does not accelerate smoothly from a full stop to about 30 mph. The acceleration is staggered. I had the transmission checked and everything was okay. No codes. Can anyone tell me if the uneven acceleration is due to plugs and coils? Would the problem go away if I replaced all the spark plugs and ignition coils? Thanks

Not sure what having your transmission checked means, but the absence of codes doesn't necessarily mean it's not your transmission slipping. Over time the friction modifiers in the transmission fluid tend to degrade away and changing the fluid will result in smoother acceleration.

You can always add shudder fix if you don't want to change the fluid just to see if the cause is degraded fluid.

[CTinline-six]

Originally Posted by e91Owner

Not sure what having your transmission checked means, but the absence of codes doesn't necessarily mean it's not your transmission slipping. Over time the friction modifiers in the transmission fluid tend to degrade away and changing the fluid will result in smoother acceleration.

You can always add shudder fix if you don't want to change the fluid just to see if the cause is degraded fluid.

+1

I changed my fluid at 40k miles with Valvoline MaxLife in my GM 6L45, and the shifting improved a ton. Before that it would hesitate, have jerky shifts, etc.

How many miles on the car? I would try a fluid change first.

Also, coils and plugs can cause slight misfires before failing completely and throwing a code.

[theMeeks]

FWIW - I had a similar issue with my N52 sputtering on acceleration from a stop. No codes, but replaced all 6 plugs and coils and that resolved the issue.

[ppointer]

Originally Posted by supercharger

I have a 2009 328i. My car does not accelerate smoothly from a full stop to about 30 mph. The acceleration is staggered. I had the transmission checked and everything was okay. No codes. Can anyone tell me if the uneven acceleration is due to plugs and coils? Would the problem go away if I replaced all the spark plugs and ignition coils? Thanks

Although I hate to throw parts at un-diagnosed problems, if your 328 has 100k miles on it and the coils / plugs were never done, I would order a set from FCP and change them. Last kit I bought was about $250 total. Takes about an hour or so. Plenty of YouTube videos out there to walk you through it. Only special tool I had to find was a thin-walled sparkplug socket.

[Korz55]

Agree - also have a 2009 328, plugs are worth doing - and coils are worth it just due to the age (one of mine went bad when I changed the plugs). It may not fix the problem, but will definitely make it run better. On a 328 you don't need a special thin-walled socket.

[ppointer]

Originally Posted by Korz55

... On a 328 you don't need a special thin-walled socket.

I definitely needed thin-wall socket on my 335i. Then used it on my 528 (e60) and e91 rather than my normal plug socket. So, you're probably correct about that!!

[theMeeks]

I surprisingly just used a standard spark plug socket without issue

[Phil325i]

Originally Posted by ppointer

I definitely needed thin-wall socket on my 335i.

Not just a thin wall, but you should use an articulated one. See this NGK vid which although for the N43, applies to the six cylinder 335i engine too...

[CRtoE92]

Had Regurgitation and hesitation on low rpm. Did not throw codes. Almost felt like transmission problem.

Did a ton of research and replace coil packs and plugs

Drives a like new