BMW 325i 2005 misfire

Update.

I had to buy a different adapter to work with my car on the Android version of bimmerlink. I got a Vlinker MC+, I will return the Veepeak one.

This allowed me to register new battery, which as suspected one had never been registered before.


On the aux belt, I went into a local BMW indy which has a very good reputation and which I used before to do my rocker cover gaskets. They had a look at the belt and the area around the crank pulley and think that no further damage has been done. Hopefully they are correct. The only way to be 100% sure would be to drop the oil pan.

I will keep an eye on things closely, but the belt I fitted appears to be running just fine, so I think it was fitting error and the belt I had replaced just five months ago probably got chewed up in the first few hours of it being done. I reckon they didn't slot it into one of the pulleys properly, so it was misaligned and rubbed on something, causing it to rip apart. Lucky escape.

Lesson for everyone, if you get a garage to do any work, always check it after. Cannot trust hardly anyone these days.


All that is left to do now is fit the new oil cap, but its raining so that's a job for tomorrow. Hopefully that seals better and I can then see if there is any more oil seepage from anywhere else.
 
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Just a thought - not read the whole thread, but I did have a very similar problem with my 06 plate E91 325i. Would have been the same N52 engine as yours, before the 325 became the detuned 3 litre N53…

My car would occasionally misfire from a cold start. You’d bumble out the village, but the first time you went to accelerate, it’d hesitate, misfire, put itself into a rev-limited limp mode, but not throw an engine management light. If you pulled over and turned the car off and on again, the problem (as with yours) miraculously disappeared.

Various garages drew a blank until a good local specialist diagnosed an issue with the oil pump supplying the vanos unit (and possibly the vanos unit itself, my memory fails!) It was failing and with thick, cold oil, was not able to supply sufficient oil pressure to the vanos unit upon demand, causing the hesitation/misfire.

The garage ended up taking the top end of the engine apart and replaced a load whole number of parts, rebuilding the pump and bits in the vanos unit. Cost £1800 (ten years ago now), but every part they took off and replaced appeared to be slightly different or redesigned. Their theory was, having seen it before, was that the early N52 engines had this issue which BMW addressed with a later update - hence all the updated parts.

The car’s run faultlessly for 10 years and 120,000 miles since.
 
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