[Stoatmaster]

Evening all,

Recently my '08 E92 330i has developed a slight roughness to its idle from cold start, with occasionally hunting. Once the engine is warmed up, this issue disappears.

Can anyone advise if this is more likely a Idle Speed Sensor, or more likely an injector issue? No indication I can see from below. On my S2000 this issue is usually cleared up by cleaning the ISCV but unsure how the codes below relate to the BMW.

Carly Codes pulled show;

- Differential pressure sensor intake manifold / Pedal sensor plausibility / Air mass meter, signal correction Code: 002B07

- Intake air temperature sensor bank 1 / Intake manifold pressure Code: 002AFB

- Nitric Oxide Sensor Code: 0030DA

- potentiometer, throttle / pressure sensor intake manifold / Accelerator pedalmodule, pedal sensor 2, Working range: High Voltage / Differential pressure sensor intake manifold / Pedal value sensor 2 / Air mass meter, signal correction Code: 002B06

Are these more likely to be the culprits? Once cleared, these manifest themselves again but do not trigger any form of Engine Management alert. Car has recently been in for an oil service and it would appear BMW didn't bother checking these codes so I suspect their 'Standard Scope' basically consists of pressing the 'Check' button once.

I have an extended warranty through Mondial, would the issues above be considered separate claims, or would they resolve as one item? Thinking of the excess here!

[Phil325i]

Generally the cause of rough cold idle is an injector that weeps overnight and causes poor idle until the excess fuel burns off. Generally the piezo injectors in the N53 aren't that robust (I had to change all mine at 65K) which may be why BMW have gone back to solenoid injectors in later models.

The NOx sensor is deffo not a cause. However, from your codes it does appear you may have a DP sensor issue (not expensive and an easy DIY fix) and possibly a problem with your throttle pedal (easy DIY, but not cheap). Problems with this part are very rare though.

Hope that helps.

[Stoatmaster]

So, booked the car in to BMW and advise this is most likely an injector issue. Booked as warranty job.

BMW diagnose the NOX sensor and replace.

Unsurprisingly, the new sensor didn't fix the problem, but my MPG is markedly better now!

I'm dropping the car off again next week, but a little annoyed they didn't pass over my notes to the tech who looked the at car. Next time I'll leave a copy on the dash for them to review.

As it stands now, slight misfire still at cold as explained previously, plus I have now developed a hunting on the revs that varies between 300-1000rpm. Bizarrely, only really occurs when I press the clutch in!

At least it's easy to replicate now, so I'll advise BMW when it goes in.

[marc l]

I have the same problem with mine when it's cold.... I'm looking forward to updates

Also it's interesting to hear the NOX sensor has improved MPG. My N53 isn't good with petrol

[Stoatmaster]

Just an update, seems the technical document I provided had helped them diagnose it, and they are fitting 6 new injectors tomorrow.

Hopefully this will resolve the issue!

[jamherber]

Originally Posted by Stoatmaster

Just an update, seems the technical document I provided had helped them diagnose it, and they are fitting 6 new injectors tomorrow.

Hopefully this will resolve the issue!

Blimey, bet you're glad you got the warranty as that would be around £2k at a main stealers.

Make sure you get a replacement NOx sensor under warranty as well as they are £350 + fitting.

[Stoatmaster]

Originally Posted by jamherber

Blimey, but you're glad you got the warranty as that would be around £2k at a main stealers.

Make sure you get a replacement NOx sensor under warranty as well as they are £350 + fitting.

Had the NOx sensor done last week, told them it wouldn't be the issue but I gladly accepted a new sensor. Had approx 2.5k worth of bits now.

[Stoatmaster]

So, pleased to say the injector replacement has cured the cold running issues, although the fact they changed six did surprise me. (This misfire was quite clearly one cylinder, but I am not complaining)

Fuel economy has also improved, and the car pulls cleaner too. Incidentally, the other codes in my OP have also cleared up.

Only annoyance is despite paying and having a receipt for a brake pad change, they appear to have 'forgotten to fit them'.

5th visit now required.......

[Phil325i]

Replacing all injectors is a wise (if expensive) move. When a single injector has a fault, the others in that bank tend to 'compensate' and often if you just replace one, the others fail shortly afterwards.

[old grey steve]

Injectors on these are now getting all too common the symptoms you'll face are as Phil325 has stated plugs will be black and may smell of fuel as well but likewise as you've discovered there can be other issues re these cars they are complex but you can cut to the chase with some back to basic understanding like having all the plugs out checking their condition which gives you one visual clue, then as we do to back up a theory we put a camera down to see when the ignition is switch on then off whether we see a spray pattern if we do we know we have a leaking injector carbon build up on the bore again seen with a camera will back up what else could be taking place if you follow me.

But all I suspect that may be happening is that the injector is leaking like a leaky tap when you start the car up and run it its trying like mad to burn off the excess fuel after a while it will calm down to a degree only to sadly return.

Some say replace just the offending injector, me I'd replace at least one bank of injectors or if money is OK all of them again as Phil's stated and hope that the other bank haven't be compromised by trying to compensate.

But sadly as stated an all too common complaint on these cars with this engine which is also mirrored on the N54 of which I've got one here now with again a leaky injector

For instance plugs out igntion switch on/off you shouldn't see this sort of thing once the ignition is off (pictures are from different cars the bottom 2 ae N53's)one of may of my leaking injector video collection





When lit up anda still taken

[Stoatmaster]

Very interesting. Thanks for posting that.

[Stoatmaster]

So, took her for a good run last night, and noticed two tiny misses when accelerating on light throttle. Dismissed it initially due to me being a little paranoid about things after the injector replacement, but just pulled the codes and;

Engine / Motor
:Rough running stratified charge operation
Code: 003104

It's back into BMW tomorrow for the brake pad change they forgot to actually perform last time, so I will mention it and ask them to plug the diagnostic machine back in at the same time they are doing the pads.

[Dormermike]

I get that code occasionally even after BMW replaced all injectors. Be interesting to hear what you find out.

[Stoatmaster]

Originally Posted by Dormermike

I get that code occasionally even after BMW replaced all injectors. Be interesting to hear what you find out.

They cleared the code and said 'If it does it again bring it back'

Not particularly helpful.

[Dormermike]

I find my idle is very much more noticeable when the AC is on compared to off and wonder if that's what triggers the code. Yours similar?

[Stoatmaster]

Idle is spot on now, in fact the original issue has completely gone away.

The latest code was thrown when cruising on the motorway and I applied throttle. There was a minor hesitation and then it recovered. This has only happened since the injector replacement, it was absolutely fine before that.

Perhaps it won't be an issue in the future, I'll reserve judgement on that though.

[tim.buckley]

I've bought a 2007/57 325iSE with N53 engine and it has turned out to be a lemon. It came from an independent garage, a small company with about 20 used cars on the forecourt. The engine management light came on whilst it was being unloaded from the transporter. Since then it has misfired and idled worse and worse each day. It's been at my local garage for a few days (the garage I bought it from is paying) and so far it has had a new high pressure fuel pump, a new set of spark plugs, a new low level fuel pressure sensor and the injectors have been removed and visually checked. The next step is to send the injectors off for testing.

I spoke to my local BMW dealer and they informed me the car has had three repairs under warranty / recall in 2009, 2010 and 2012. I don't know the order but they've changed 4 injectors for new, replaced some coils, and replaced NOX sensor too.

The car has just under 74k on it, 4 BMW main dealer stamps and one independent stamp. Only 1 previous owner.

Car feels like an absolute lemon, if the car isn't running right by the end of this week I'm going to tell the garage to take it back and give a refund. Shame as it's a nice car and what I wanted at the time.

[Stoatmaster]

A visual check of the injectors may not reveal any issues, a proper bench test will most likely be required unless you can do a boroscope that Steve indicates above.

At least if the injectors are found to be the problem and resolved you've had a large degree of the fuel system replaced for free.