LKwok

Hey guys, I have a 04 545i with roughly 110k miles on it. I bought it about 2 months ago, and every since then I notice that sometimes when I startup the car, it's rough and takes a bit longer than it should. The car shakes a little more and it sounds as if it is having trouble fully starting. The extra delay is maybe 1 second, if not 2 tops. The thing is this doesn't happen all the time, only sometimes. Someone told me it might be the battery, what do you guys think? Thanks!

azn_outkast

maybe your alternator is going out, thats my only guess

LKwok

Ok, thanks!

nightowl2k2

I had a very similar problem with my '03 330i. It was the starter that was going out and it ended up finally dying on me and I had to have the car towed to the shop. Does the problem seem better or go away if it is a warm start?

LKwok

It is definitely better at a warm start. But even now, I'd say its 50/50 on cold start, if not a little less. I am guessing the starter is the alternator?

pcy

Starter starts the car. Alternator charges the battery while providing power for running the car.

Battery power is used while attempting to start the car. Alternator doesn't start the car.

RTR

Is the battery original? If you don't know, open the battery compartment and check the production date on the negative terminal of the battery (should be stamped on the top of it). If it's original, it's pretty safe to say you need a new one.
Alternatively you can check the battery if you know how to (or you guys have autozone that checks for free, right?).

If the battery is low, but it's a new one, check the alternator.