BMW E46 330ci stalling when warm issue

[E46330]

Hello, a few months back my 2004 330 cut out on the motorway (on a bank holiday Monday of all days!) which resulted in an expensive tow home and a new battery and alternator (along with a new water pump and thermostat as the specialist noticed they were on their way out). Since this my car has developed a new problem which is that it stalls or hesitates when pressing the throttle but only when started up warm (can sometimes be after just a 2-3 mile journey). When started up cold it runs absolutely fine. I took it back to the garage where it was fitted with a new breather system and disa valve however the problem still continues.

After a lot of research online I have noticed a few people with similar problems and the cam shaft (inlet or exhaust) / crank shaft position sensor problem keeps cropping up. I have a few questions before I buy new ones and install them.

1. Of the 3, cam shaft inlet sensor, cam shaft exhaust sensor and crank shaft sensor which is best to try first
2. I have read of poor quality sensors breaking again within 6 months and to always buy genuine, but autodoc.co.uk sell sensors for 10% of the cost and have a 2 year warranty, is it worth the gamble?
3. The two cam sensors appear to be the same, are they?
4. Do the o rings also need replacing

Any help would be hugely appreciated.

Many thanks!

[BFleming]

1. Hot starting issue suggests crankshaft sensor first.
2. Aftermarket sensors are generally rubbish (in my personal experience), irrespective where bought. Genuine BMW is what I'd recommend.
3. No, they're not the same. I seem to remember the inlet manifold sensor has a cable attached, the exhaust one doesn't.
4. O-rings, yes for the sake of a few pence, replace them.

[naturalaspiration]

I would suggest reading out the ECU error log instead of randomly replacing expensive sensors. However, as already written the sympoms do point to the crankshaft sensor. I have been very pleased with sensors from Febi/Swag (same company) as they seem to be repackaging the OE Siemens/VDO units - with the BMW stamp ground off.

[naturalaspiration]

If unsure as to what you need go to bmwfans.info, type in last 7 digits of the car's chassis numbers, and then get the part number(s) you need - diagram group engine electrical. Then just copy/paste into autodoc page search.

[E46330]

Thanks all, autodoc don’t seem to have one for the petrol 330 so will have to look elsewhere.

Is there anything else besides the crank sensor that could be causing these issues?

[BFleming]

Look for unmetered air entering the manifold - hard to spot, but a split grommet at the back end of the manifold can suck in air, causing the hesitation you describe.
By the way, a camshaft position sensor will throw error codes; a crankshaft position sensor won't.

[geeks]

If it was the crankshaft sensor it would most likely fail to start period

[BFleming]

geeks said:

If it was the crankshaft sensor it would most likely fail to start period

They usually cause hot start issues first. Complete failure out of the blue is rare.

[DaveZed]

I sorted out similar symptoms on an E46 330i recently (occasional hard starting, stalling, hesitation on acceleration) by replacing the inlet cam sensor. Diagnosis was via a P0340 error code. It's been perfect since.

Interestingly, the replacement sensor was a few millimetres larger diameter than the original one, but I confirmed with a BMW technician that provided the length is identical it would work fine.

Edited by DaveZed on Wednesday 3rd July 14:30

[naturalaspiration]

As said, you need to get the error log read and then you will know what exactly needs changing. Cheaply done with Bluetooth OBD2 dongles and free smartphone apps.

[naturalaspiration]

E46330 said:

Thanks all, autodoc don’t seem to have one for the petrol 330 so will have to look elsewhere.

Is there anything else besides the crank sensor that could be causing these issues?

Sure?

Intake:
https://www.autodoc.co.uk/febi-bilstein/1881619
Exhaust:
https://www.autodoc.co.uk/febi-bilstein/1881298
Crankshaft
https://www.autodoc.co.uk/hella/10117941

In my case it was actually the camshaft sensor which died - symptopms were hesitation and difficulties to start the engine - but I alwas did manage to start it in the end. Later the crankshaft sensor started to play up - and this was a total outage. With regards to the camshaft sensor only Febi worked really well (and still does two years on) - tried Delphi first only to return it.

If you are having issues with diagnostic you may get the lot and start with intake camshaft senor - if all good just return the rest for a refund.

Edited by naturalaspiration on Wednesday 3rd July 18:41