Diagnosis help - 330Ci fuel injectors

[E63eeeeee...]

Hi

74k miles 53 plate 330Ci, EML has just come on. Long term fuel trims have been over 11% since I picked it up last week from where it was stored for over 2 months and hit 12% on long drive yesterday. Lean codes on both banks but nothing else helpful. I went through all the vacuum leak stuff in October and the big intake boots are new, trims looked great last time I checked in the autumn after everything was fitted. Had a prod around earlier and nothing obvious wrong.

I did find this in the diagnostic tool under Fuel Injector Adjustment. The numbers fluctuated slightly while running but the pattern of three at 70-80% and three close to zero seemed to be consistent.


Anyone know what this means? Is it showing what the ECU is telling the injectors to do or what they are actually doing? Is this pattern normal? What does it mean that it seems to be trying to solve my low fuelling in just three of the cylinders? Do I need new injectors? If so, which are the dodgy ones? Is this just a red herring and it's back to tedious leak chasing?

Any insight or clever ideas much appreciated. Thanks.

[RUSSELLM]

Out of interest, what fault codes are you getting ?

[E63eeeeee...]

Same ones (apart from the O2 sensor one) I was getting last year that I fixed with the new intake boots.

[RUSSELLM]

The 61 fault code....

Is that not indicating a fault with the Oxygen sensor ?

[helix402]

RUSSELLM said:

The 61 fault code....

Is that not indicating a fault with the Oxygen sensor ?

Certainly is.

[330ti]

Have you put fresh fuel in it yet ? Lean codes are normally vacuum leaks. Check inlet boots first.

[E63eeeeee...]

330ti said:

Have you put fresh fuel in it yet ? Lean codes are normally vacuum leaks. Check inlet boots first.

Thanks. Yes, fuelled up with optimax yesterday. Upper boot replaced in 2018, lower in October, both still feel flexible and no obvious cracks or holes. Last time to get to 12% I had two cracks a quarter of the way round the lower boot so I suspect I'm not looking for a pinhole here.

[E63eeeeee...]

helix402 said:

RUSSELLM said:

The 61 fault code....

Is that not indicating a fault with the Oxygen sensor ?

Certainly is.

Thanks. Would one broken post-cat sensor cause problems on both banks? I've been assuming I'm looking for something intake manifold back as it's pretty consistent across both. When I've looked into this before I've read that post cat sensors don't do much other than tell you your cats are knackered. Pre-cat sensors seemed to be acting normally (I.e. oscillating between low and high voltages).

[RUSSELLM]

No experience of BMW’s or their fault codes, I’m afraid....

But I presume that 61 code is referring to the heater element of the O2 sensor ?

If so, I’d want to know what’s causing that.

Does that fault come back after a clear/drive/read ?

[E63eeeeee...]

Well, I definitely need a new post cat o2 sensor.

Just reset the codes and ran it for a bit. The lean ones didn't come back but the o2 error did and it's just sat on the same voltage.

Unplugged the MAF, not noticeably different but it did reset the fuel trims, so probably needs some driving now to see what it settles down to.

I did notice the engine does a little huff or sneeze every 30s or so, sounds like it's releasing some pressure somewhere near the rocker cover. It might have always done that, but anyone know if that's normal or what it might be? Thanks all.

[RUSSELLM]

As a side note, to something you mentioned earlier...,

On the cars I work on, I was always under the impression that all of the O2 sensors are utilised, once the car’s in closed loop.

I’m probably wrong though

[E63eeeeee...]

Cheers. I'll get a new one and see if you're right.

[blank]

It looks like a faulty O2 sensor on the "bank" that comprises the cylinders with the massive adjustment values.
Although the numbering in the app looks like it might be wrong, assuming the exhaust is split 1-3 and 3-6 otherwise it's suggesting the 3 suspect injectors are spread over 2 banks?

Either way it's unlikely that all 3 injectors are faulty in the same way, so it looks like the O2 sensor for those cylinders is detecting lean running and then upping the fuelling to compensate. These values are essentially cylinder specific fuel trims.


What app is that by the way? It looks a bit like an easier to use version of BMW Deep OBD!

Edited by blank on Tuesday 2nd March 08:27

[RUSSELLM]

I was thinking the fault codes looked a bit short.

Is a Three digit fault code all the dealerships see too ?

I did notice that it’s put the code under the reporting module (Engine), so I presume that does away with some numbers

[E63eeeeee...]

It's an android version of Bimmertool. I tried about three or four and this was the one I settled on.

[Foz2021]

Just echoing what 330ti said. Do a vacuum leak test first before you start buying parts. Most likely it could be perished gaskets from the rocker cover, oil filter housing and also manifold. These engines are getting on a bit now.

I recently had my Rocker cover gasket and Oil filter housing gasket which sorted out my fuel trim issue.

[Krikkit]

Yeah I bet this is a vacuum leak, although heater failure on one is quite common. Mine currently has both sensors not heating but doesn't cause any issues.

[E63eeeeee...]

Thanks both. That sounds like a plan. A gasket leak might make sense as the EML only seems to come on on long drives after about 2 hours, and it seems to be settling in single figures on LTFT when I use it more normally. One for the summer, I think. It won't damage the engine to run a bit lean will it?

[Foz2021]

I’ve had it running for half a year like this. Haven’t really seen any adverse effects from doing so.