F10er

N46 doesn't have an idle control valve. Idle is controlled via the valvetronic (valve lift) and throttle body. Have you scanned the car for fault codes?

The most common cause of this is cracked engine bay partitions. They start cracking and falling apart from the heat. Are yours intact?

The earth wires in the tail light plugs are a known weak point. I would look there first.

Odometer wind backs are extremely common in BMWs from Singapore. I have personally witnessed this, some with over 100000km wound off. If you are serious about the car, make sure it has a "verified odometer" inspection. I would also ask your BMW dealership to look at the warranty repair history. All repairs done at any BMW dealership are recorded in their system and it has a mileage reading recorded.

Low compression on one cylinder won't cause a no start situation. I think they're barking up the wrong tree there. Next logical step would be to check the valve timing.

Totally agree with Eagle. Repco and Supercheap are an absolute ripoff. Far cheaper to by a genuine filter from BMW or go to BNT and get a Hengst one for $28. Hengst make oil and other filters for BMW.

You could try testing for voltage at the glow plugs when the ignition is turned on if you haven'talready. The glow plug controllers are a known issue, so it's possible it's not working and/or logging fault codes.

Is it logging any glow plug faults now? If it is that maybe your issue with it being so cold down there. It sounds like it is firing when cranking but probably only on 1 or 2 cylinders.

When you're cranking the engine do you see an engine speed signal from the crankshaft sensor in Ista? Also this mighy sound dumb but what's the condition of your battery? Could you post a vid of the engine while cranking?

Are you able to get hold of any diagnostic software like INPA or ISTA? It would be handy to know the actual pre supply fuel pressure. The pre supply fuel pump maybe working but could be producing low pressure. It should be about 4 bar from memory.

Bump

Firstly you need to get the car scanned for fault codes. There is no way of knowing what is wrong with the car without fault codes. If you post the codes here somebody may be able to help.

Yes definitely replace them. They are 100% one time use only being aluminium. Like you said, you don't want to end up doing the job twice. BM Parts or Import Parts Specialists should have them. They may even have the starter for a reasonable price as well.

Does your car have CIC or CCC? If it's CIC there is a guide in this link. It is for E90 but it would be very similar if not identical i would imagine as hardware is all the same. This is a UK based forum but they have the same DTV format as us i think https://www.e90post.com/forums/showthread.php?t=1066295

GUIDE TO ISTA+.pdf

Definitely sounds like hpfp. Do you know anybody that has ISTA? There's a test that it can do on the hpfp that determines if it's any good or not. And I'm almost certain there's also a test that you can run which tests the low pressure system as well.

Looking for a diff head for an E60/E61 530d, 535d, or 525d. Must be in good condition.

Import Parts on St Asaph St Chch are quite reasonable and have OEM parts.

You could probably code it back in with NCS Expert while still leaving it in Oceania. Using NCS Dummy would make it easier as well as it translates all the coding options into English. I'm almost certain I've seen options for MD while coding CCCs before.

My n52b25 and n52b30 run fine on 95, both are Japanese imports. There's definitely something wrong with your car. The response you got from Cooke Howlison sounds like a typical bull$hit dealership. I would suggest bypassing them and find a BMW specialist. If the check engine light comes on, there will definitely be codes stored in the fault memory.

Looking for a Rh Lci e90 tail light with bulb holder. Cheers.

That doesn't sound good. It should run on 95 without a problem. What fault codes are you getting when the engine light comes on?

BMW dealers still use the Castrol 10w60 TWS motorsport oil for E46, E9X and E6X M cars. For everything else they now use Shell. I don’t think Shell do a 10w60 equivalent.

For the rough running fault i would suspect the injectors. The N53 (which i think your engine will be as it's a UK spec) is notorious for injector issues (especially cold start misfires) and I'm pretty sure there was a recall issued for the injectors in the UK. Can you know if that recall was ever done? For the starting issue, it could be a corroded main engine earth cable (known to corrode especially on UK cars) Or the other possibility is where battery cable passes through the body from the battery compartment. There is a connection there that often corrodes if there has been water in the battery compartment. You have to remove the battery to check this which is a bit of a pain on a convertible.

Who has been diagnosing the car and are there any fault codes stored in the car?