[Jet1990]

Hi all,

Ill keep it short and simple as im running into a few issues with my newly bought 330i.

bought a 57 plate 330i N53 on 70k back in feb and all seemed fine except for a fault code saying nitrogen cat ageing. Ive noticed that the car always idles a little lumpy on a cold start for the first 10 mins or so and then levelled out fine.

Last week the engine management light came on within a minute of starting the car to go to work. The car was clearly misfiring (ended up sounding like a subaru), turned the car off and on again and started driving it and all was well. Took it immediately for a diagnostic and an error code came up (misfire combustion cylinder 2) but by this time the engine was nice and warm and was running fine.

so one thing ive concluded is that the misfire and engine light only comes on once the engine is fully cold i.e first thing in the morning or at the end of the working day (half 5) and upon turning the engine off and back on it runs fine.

i thought it might be the coil so i replaced it with a genuine bosch coil and it still has the issue. Im leaning towards a dodgy injector now. so the plan is this saturday to swap the injectors between two cylinders and hopefully the cylinder misfire code will jump cylinder and then i'll replace the injector.

The car has had a bit of recall work done.

oct 2008, all 6 injectors replaced
aug 2012 all 6 coils replaced
feb 2016 injector 5 replaced.

any thoughts on this?

thanks

[Jet1990]

also car had a full service from the previous owner before me buying it

[marc l]

I have recently bought a e93 325i with the same n53 engine as you. I also sometimes have erratic idle when cold and I believe it's due to a faulty injector or maybe 2. I have no engine management lights on and currently don't have any diagnostics equipment.

Im looking forward to updates

[AWSAWS]

Carbon buildup on the inlet valves perhaps or maybe just a bad spark plug?

Worth trying new spark plugs if they are fairly old or more than 20,000 miles. Could even change the one in cylinder 2.

[old grey steve]

From your description I'd say like marc has stated you're most likely going to have a weak injector on your hands. But they are numerous other possibilities sure plugs, coils, inlets being coked up seen every single on of these faults n numerous cars but the first thing from the description I'd look, at would be injectors.

If as you say injector 5 was replaced in Feb this year(and coded) you'd have to ask why this took place, then due to that injector failing No4 or No6 May have been working harder to support No5 which is how the car operates which ideally is why if you have a single injector issue say on either bank 1 and bank 2 you should at least ideally replace the other injectors per bank if one has been playing up as the other 2 would of been playing a supporting role and may have over time been compromised.

The other question I'd ask is whether No5 injector is the same soec as the others as ideally the injector banks should be matched you can tell this via part number/injector body colour, if say you've got grey/black body injectors this isn't ideal

Due to these knock on effects BMW really opt for replacing all 6 if an injector goes down, which on the wallet is harsh, but they opt to do this due to the above and the fact that historically as we've seen in the past replacing just the offending injector sometimes is only a short term answer.

Don't get me wrong I've seen a single injector replaced and the cars been as good as gold but on the whole when this has been done it's usually a short term fix or once one duff injectors replaced another one or more in the chain will start to play up with a new injector in place.

Routine also states replace coils/plugs for the offending injector(s) again ideally at least per bank, as these can have an effect the plugs if you remvevinspect even smell them may smell of fuel

But from start up if you have a weeping injector you'll have neat fiel in the bore(s) that will need to be burnt off and on start up most likely this will result in a lumpy idle, like the cars attempting to clear its throat and sadly on these very common as well

[Jet1990]

My thoughts exactly. The plans to swap over injector 2 and 3 today. Our snap on diagnostic tool has the ability to code injectors. Will this be a requirement when swapping two over ( and if it is a dodgy injector is it most likely that the fault will jump cylinder in terms of fault code readings)

[Dormermike]

Any merit in swapping to a different bank than same bank?

[old grey steve]

Originally Posted by Dormermike

Any merit in swapping to a different bank than same bank?

There is perfect logic re this as you're hopefully moving a "suspected fault seen on bank to another" you'd do the same thing re sparks and coils in most events...

When we look st injectors we look for carbon build up plus plugs our we place a camera down to inspect the suspect injector(if this is the case of course)will either be seen misting(thus dumping neat fuel in to the cylinders)or we usually see carbon deposits in the injector itself in situ or will be able to see evidence on the piston crown/cylinder walls etc. if you follow me. I've some pics of injectors actually spraying when they shouldn't which time permitting I'll post up along with a video.

Worth checking to see if the injectors match re spec too as mixing new/old though it can work can bring up issues too.

I'm guessing which I didn't post due to time earlier thst the HPFP/LP side of things are up to scratch as well

[Jet1990]

My mechanic wasnt comfortable swapping the injectors over in case any seals were damaged along the way so im going to call BMW for a price on a new injector and bite the bullet with it. Euros have quoted me 175 inc vat trade price for a "OE quality" injector.

in other news..dont know if this is related. Did a 400 mile round trip yesterday to london and back and when i got home the low oil level warning light came on saying its at minimum and needs topping up with a litre asap. the car had a full service in feb so could this be normal consumption? there's no visible oil leaks anywhere in the engine bay.

[Jet1990]

Also, took the spark plug out of the cylinder on Saturday. everything looked fine with it so im leaning towards the injector.

[Dormermike]

If the spark plug looked fine as in not sooty nor oily I'd check the plugs either side. It's not unheard of to have a misfire caused because of a fault on a neighbouring injector. Basically as I understand cyl1 injector could be leaking causing a rich condition. As the bank is monitored as a whole the ecu back's off all 3 injectors which causes an overly lean condition on the other 2 cylinders

Or something like that.

Either way if you pop all the plugs out the old rules still apply. The sooty one is the rich one.

[Jet1990]

Wouldn't a faulty spark plug result in a constant misfire and not an intermittent?

[Dormermike]

Not necessarily.. engine load can bring out intermittent faults for example

[AWSAWS]

Originally Posted by Jet1990

Wouldn't a faulty spark plug result in a constant misfire and not an intermittent?

No, the faster the car is revving, the faster a spark will need to be generated. If the plug is bad and it takes longer to form the spark then you'll get a misfire top end more often than low end. Worse it gets, more often it'll happen low end as well.

Get some injector cleaner. The nozzle might just be dirty and plugged. It's worth trying for £10 to £15. Unblocks the nozzle. Makes the spray pattern healthy again.

Get redline SI-1 as it as the highest PEA (polyetheramine) content. Don't buy redex or garbage like it.

[Jet1990]

I used to redex over the weekend haha i have a few days before i commit to buying the injector so I'll look to source some redline

[AWSAWS]

Originally Posted by Jet1990

I used to redex over the weekend haha i have a few days before i commit to buying the injector so I'll look to source some redline

From what I read (and I can't gurantee it's true or not), redex is just dyed red parafin/kerosene but the Redline contains the greatest concentration of PEA, which is one of the best detergents known. Techron was one of the first products to use PEA but Redline looks better to me. I've already put some through my fuel system as I suspected a leaky injector or one with an imperfect spray pattern. I've not had the issue since.

[Tr1ppy]

Following. My N53 330I has the same issue as OP of lumpy idle when cold.

Also have fairly high oil consumption; 1 litre required every 1500 miles but not sure if this is related to injector/coil/plug problems.

[Jet1990]

issue is still here. Ordered a bottle of redline injector cleaner so hopefully this may resolve the issue. if not, a new injector will be ordered.

[abeardo83]

Would running VPower not do the same as the injector cleaner?

[Dormermike]

No

[AWSAWS]

Originally Posted by abeardo83

Would running VPower not do the same as the injector cleaner?

No, simply because the concentration of PEA is so much higher and there are other detergents etc in there.

It's also an octane booster so have a good run in the car.

I've read that driving the car at around 4000 rpm for 20 mins or so on the motorway is also good for engine cleaning. I'm not talking about DPF regeneration. I mean for burning off carbon deposits. Worth a shot. It's probably partially to do with all the fuel (and it's detergents) going through the engine but it also keeps the car out of exhaust\inlet valve overlap where emulated exhaust gas re-circulation can cause build ups. Worth a shot.

[Jet1990]

update - redline cleaner has arrived today. £15 from ebay. Instructions state to empty full bottle (443ml) before full tanking it. Hopefully fingers crossed this works.