Idle Issues?

[youngdoc1]

Hey all,

I have a 2009 128i w/ auto transmission that I bought a few months ago with 32000 km's and now it has about 36000 km's on the clock. I've noticed that since I bought it, I've been experiencing an odd sensation at idle.

The car idles smoothly at around 650-750 rpm but when I am stopped at a stop light with the car in drive, there is a slight dip in the RPM (just above 600) for a couple of seconds and there is a vibration in the steering wheel and through the seat. The engine note also becomes a slightly lower frequency. This seems to cycle on and off every few seconds when the car is at a stop, and the vibration is less intense with the AC on (the idle RPM is also slightly higher).

There doesn't seem to be a difference between cold start and when the car is warm, and otherwise there is no vibration at any other time. There is no hesitation or engine pinging at any time, and the car accelerates very smoothly. There are no CELs or any odd noises. I only use Shell V-power and just put in a bottle of STP fuel injector cleaner.

By googling, I found that this seems to be a common occurrence with the N52 engines even when they are fairly new, and I just wanted to ask if this is something I should be worried about? Has anyone else experienced this in the past?

Thanks in advance.

[1911A145]

Could be cause from the electrical draw from the fan causing the the rpm's to drop slightly and the car cooling off while at a stop and then oes back to nowmal when the fan kicks off. My only logical guess. Seems pretty normal for all cars. You will have some type of feedback like this on all cars really.

[youngdoc1]

Originally Posted by 1911A145

Could be cause from the electrical draw from the fan causing the the rpm's to drop slightly and the car cooling off while at a stop and then oes back to nowmal when the fan kicks off. My only logical guess. Seems pretty normal for all cars. You will have some type of feedback like this on all cars really.

I understand, I've felt this before on previous cars. This is different though, when I have the AC on everything is fine, then when i turn it off, the dashboard and seats have this low frequency vibration almost like a massage chair. It seems to be becoming more and more persistent, and the idle without AC sits just above 600 RPM, which is when i feel it. The second i touch the gas or let off the brake the vibration goes away.

Any other thoughts?

[Dackelone]

Originally Posted by youngdoc1

Any other thoughts?

Spark plugs. They are cheap and make a huge difference on how the engine idles and performs. Even though they can last 100K... I certainly would not run them that long. I would also pay close attention to your coil pack connectors when you R&R the plugs.

You could also ask your dealer... maybe there is a new-er SW to address this issue?

And of course when all else fails... we blame it on carbon buildup!

Dack

[1911A145]

Originally Posted by youngdoc1

I understand, I've felt this before on previous cars. This is different though, when I have the AC on everything is fine, then when i turn it off, the dashboard and seats have this low frequency vibration almost like a massage chair. It seems to be becoming more and more persistent, and the idle without AC sits just above 600 RPM, which is when i feel it. The second i touch the gas or let off the brake the vibration goes away.

Any other thoughts?

I think you are just getting some very normal feedback. All of my cars, including the bmw, act the same way as you decribed.

[youngdoc1]

Originally Posted by Dackelone

Spark plugs. They are cheap and make a huge difference on how the engine idles and performs. Even though they can last 100K... I certainly would not run them that long. I would also pay close attention to your coil pack connectors when you R&R the plugs.

You could also ask your dealer... maybe there is a new-er SW to address this issue?

And of course when all else fails... we blame it on carbon buildup!

Dack

Hmm. Thanks for the advice. I think at 36k km, it is a bit early for spark plugs. I guess it could be a single cylinder misfire caused by a defective plug or ignition coil, or even a loose engine mount.

As for normal feedback, i wouldnt expect normal engine vibration at idle to make the whole car vibrate like a massage chair. I've also driven several other bmw's, including another 128i and a 328i, and neither gave me this kind of vibration when i was waiting at a stop light. I will get it checked out this tuesday and keep you guys updated.

Thanks for the advice!

[kennethhhhd]

Im no expert so I won't claim to be. I got my 135i back today from the dealer. I was noticing a rough idle while at a stoplight as well before I took it in but I had other issues with it as well. They replaced the high pressure fuel pump. I have to take it back again tomorrow because im not sure if they fixed the problem all the way or just caused another issue.

[youngdoc1]

Hey,

So after a few hours at the dealership and not finding any faults with the engine, techs increased idle rpm levels slightly and problem is solved!

Thanks everyone for your advice.