so far i have 50k on my 2003 325ci manual. i'm from chicago and lately it's been cold out in the mornings. if and when my car hasn't been driven for a a day or less couple hours say when i start my engine as soon as it starts i hear this noise as the engine starts, nothing really big but wasn't there before or actually last winter. all i've done so far is oil changes at 7k, pads and rotors, normal maintence. thinking it's about time i change my transmissino fuild diff fuild, how about plugs and wires? could that be a problem? fuel pump? pcv valve? i'm thinking about taking it in to dude performance for regular maintence, so far as mods wise i have dinan cai, dinan tb, stage 3 and dinan exhaust. so at 50k what types of maintence should i do? please help :D

Could you describe the noise or where it sounds like it comes from?

is it like a slight backfire pop noise? That what mine just did it died tonight and after i jumped it , it made a pop noise like a soft soft pop

Bad gas? Get one of those cheap gas stabilizer products?

Also, 7K mile oil changes......?? To me, that seems a little long.

You don't have any wires. You have coils that sit on top of each plug.

I would think that your computer would pick up an internal problem with your coils, emissions, timing, etc.?


is it like a slight backfire pop noise? That what mine just did it died tonight and after i jumped it , it made a pop noise like a soft soft pop

Is it a belt noise? It's been very cold here in Atlanta and my belts are glazed so I'm getting some intermittant chirping. New belts are going this week.

Pop noise? Kind of like a slight backfire on cold start?

Bad gas is a possibility, check there first. Add in some dry gas or some fuel stabilizer to see if that's the prob before moving on to more expensive and time consuming diagnosis.

It could be coolant temp sensor bad. Hard starting can be a number of things but it sounds like you are getting too much fuel for a cold engine to fire, like being flodded out. The amount of fuel is being controlled by your injectors whose pulse is controlled by the ECM (DME). If your coolant temp sensor is bad or failing it can cause incorrect fuel delivery. Too much unburnt fuel can cause a backfire when the unburnt fuel hits a hot exhaust. Also your mods could be suspect if this is your first winter with them

Another thing to consider is a bad or fouled plug or ingition coil. Check them all with a multimeter to confirm proper voltage/resistance.

As far as maintenance at 50K, check your owners manual, but at that point on the clock you really shouldn't have too many things on the list other than; Cabin microfilter, oil, oil filter, maybe a coolant flush, maybe a brake flush, check brake pads/rotors, air filter, fuel filter (might be a good idea in this case), clean injectors/throttle body, check proper operating ranges for sensors. Just usual maint stuff. Fluid changeouts like diff, tranny, etc don't normally occur until around 100k, same goes for plugs. You can expect to buy new O2 sensors around 75K, so put away about $500.00 for that. That's all I got for now.

Good Luck!