after doing some searching in these forums, I feel that I need to change my spark plugs due to my rough idle issue. The MAF is less than a year old and I also had the valve cover breathers? replaced since the dealer said they were torn. Does this seem like a logical repair for me to replace the spark plugs? Also do I need to replace the coil packs? I am NOT getting any misfire codes, however, ever once in a while Ill get an iDrive engine malfunction warning.

2005 545i with 99,300 miles

thanks for the help guys

 

I would definitely change your spark plugs, especially if you're still running on the originals.

I just did the 60,000 mile service on my E60 last weekend (2008 550i), including new plugs. My car was running fine, and the engine is in tip-top shape (had the oil analyzed at Blackstone and got a glowing report), but boy howdy I can tell you that I noticed an immediate change in how my engine runs with new plugs! It idles much smoother, and takes off like new car again. I had been developing a bit of a hesitation from a dead-stop (which nearly caused an accident a couple weeks ago when I floored it to get into traffic and the engine just about quit!), but that annoyance is definitevly gone now. My car runs like she's fresh from the factory again.

It's a cheap fix with a nice bang-for-buck return.

 

You may want to change your plugs anyway if you haven't changed them already since you've had the car.

 

every once in a while if the car sits for a while idling (stop light, etc. I get an "engine malfunction reduce power" in the iDrive but no check engine light...

 

OK, i also want to add this and see if anyone has any thoughts. When sitting at a light lets say, rpms will bounce around up and down about 200 rpms, and i notice the car vibrates a bit, then every once in a while itll will be a violent shake and the car almost wants to surge forward...its really strange. anyone have an idea? or happen to them also? Alternator?

 

Not on my E60, but I've had that problem with my toyota before. Engine light on, rough idle, and at times the entire car shaked. Dealership diagnosed as one of the coil pack was bad. Subsequent to the replacement, had no issues. Hope this helps.

 

I am replacing the coil packs and spark plugs today, i just couldnt understand how the plugs and coils would cause the car to act like its going to take off at the light haha

 

A weak spark that doesn't register as a cylinder misfire will produce unburnt fuel - which causes a rich O2 condition - which tells the engine to reduce fuel to the injectors - which may increase rough idle - which causes the rpms to surge in order to avoid stalling.

Or something like that.

 

I too had slightly rough idle between 95k-103k. Replaced coil packs and plugs for a total of $290 and it seems the problem is gone. Plug service is due at 100k anyways. I'm taking a 2k mile trip on Sunday in the car so that will be the main judge of the work. I should prolly replace the MAF and valve-cover hoses soon.

GL on the job.

 

Any change to your car idle behaviour 545iNTENSITY?

I am experiencing the same thing and also think it's the plugs and coils. I will get them changed next week.

Thanks