What causes this? Now my Check Engine Soon light is on... Hmmmm

 

if my 525d isn't used for a week or more, the engine runs very badly after that. Like and old carburettor car that is dirty. Rev it a bit and all is well. After that (next days) no problems starting and running. No engine lights though.

 

Could be a lot of things.

Simple thing to do to start with would be when the tank gets low put in a good fuel addiative (Chevron, Valvoline Syn., etc.) and fill up the tank with a Shell V-Power or Chevron Premium. Main thing is try to find one with no ethanol in it. See what that does to the problem. Read an article about how many gas stations that say "contains up to 10% ethanol" when tested actually have a higher content. Highest they found was just shy of 17% ethanol. Many were in that 13% to 14% range. Basically by being that high it can cause many issues with in the fueling system over time.

Does idle odd/rough after the car is warmed up? Have found your battery dead after sitting a few days?

If the above doesn't work its time to go to the dealership. There could be just too many little things that could cause this.

 

my 08 535i does this when something is about to go wrong! its happend three time to me. car will start up and have a shutter to it,later on i get a engine malfunction reduced power light.if your car is still covered i would get that checked out soon.

 

Go to the dealer and let them sort it out!!

 

That sounds like an emissions-related problem ... maybe an O2 sensor failing. In the US the warranty coverage on most of those components is longer than the 4 yr / 50K mile.

 

Had similar problem. Took to dealer and they said it was bad gas and was 20% etoh.
I used same independent gas station for years. Added Techron to clean injectors and added Texaco gas. Problem solved.
Started research into gas quality and learned some gas supplies have more ethanol than 10 % (that is amount BMW will warranty) and many have minimal detergents (not regulated stuff). I see that I now have to clean my own injectors with gas additive and use trusted gas sources. I had prolong crancking before the rough idle and stalling at startup. Car is over 4 years old.

 

I generally find the same thing if I have only driven my 540 a short(ish) distance. The cars run rich while cold I believe and this builds up if you don't run it long enough to warm up to operating temp. I have found that if I pop on down to the local shop, the next time I drive it, it is very rough initially.

Had the same issue in my E53 X5 4.8is (same engine as yours) and it took longer to warm up as it didn't need to rev like my little 540.....

Cheers

 

I had this on my e61 525d (05 plate) 60k miles and it turned out that the glow plug control unit had failed. The dealer replaced it under the AUC warranty and cured it straight away and improved the fuel consumption.

Which was a result, as I am now gettign exactly what the handbook says I should get 35.3mpg, which cant be bad.

Good luck.

Cheers