BMW diesel help?

[dombanks 197]

can anyone make a guess at what might be wrong with my neighbours 08 plate 1series diesel? 

It started to become difficult to start. just slugishly turning over so he replaced the battery. this didnt help and the engine light came on so he had the fault codes read and it was suggested that the fuel pump in the tank was broken so he replaced this which has also not helped. 

Now it will start eventually and idle fine. but if you rev it it and hold it at say 2k rpm after 30s or so the engine lights come on and the revs sort of run away with you and then settle but are lumpy. 

 

I tried using the INPA software i use for the Z but it doesnt list his bmw E number?

[Kit Car Electronics 1,893]

Bad earth strap? 

[Blatman 685]

Leaky or intermittently stuck injectors?

Bad pressure regulator?

Fuel pump replacement hasn't fixed the issue so what is next in that circuit? Injectors then pressure regulator then return to the tank (I assume).

Sticking with the fuelling theme...

It's not getting enough or too much air, so air filter, air flow meter and then maybe O2 sensor in the zorst, if it has one.

Is it fly-by-wire? Throttle pot rears it's head if it is.

And it could well be a bad earth or power feed on any of these items that are controlled or monitored by the ECU.

[DamperMan 737]

Not sure about an E46...  but the f30 which requires a new battery introduced to the intelligent charge system. Or it results in over/ under charging and can cause voltage issues.  Without plugging it in its hard to guess.  Mechanical stuff... water in the fuel.   Diesels hate air! there’s a load of fuel pipe connectors.   fuel filter. I think is under the car by the gearbox.   

[1960dave 256]

Firstly have you told the car it has a new battery? When was the fuel filter last changed ( its under plastic trims under the car under the passenger seat) There are a lot of pressure sensors on that N20 engine I hate them. I changed the rocker cover gasket on my sons and it woudn't start ended up with a new engine loom and a new high pressure pump. Its a E87 if its the hatch model. If you need any bits let me know we bought a complete car to fix his that had broke its cam chain but all other parts are great.

[RobH72 502]

If it's got stop/start, then the battery will need registering. I use the Carly app and OBD2 reader for my BMW. Not the cheapest but will read all BMW codes and can register the new battery.

 

The runaway symptom sounds like it might be an injector issue which is overfueling and could possibly explain the difficulty starting.

 

Also, make sure to check the engine oil level. If its overfueling and is doing short journeys the dpf could be clogged

[Greenstreak-Andy D 575]

Erg valve was replaced on my 420 under warranty. Diesel and frequent short trips just don’t mix well. 

[Glen_I 188]

@dombanks if you and your neighbour were happy to send me reg number via PM, I can look to see if there are any known issues matching that description via the BMW Air/ISTA that is used in the BMW workshop. 

[Glen_I 188]

I recall EGR wiring being a known issue?? 

 

But as others have pointed out there are so many things that could be at fault, without reading trouble codes you and your neighbour could be running around in circles..