discussion Some advice - over fuelling E39 M5

[MoeM2]

Been a while since my last post, but time to seek some collective wisdom and advice.

At first I thought it was just normal to have high fuel consumption (18L/100) upward considering it is a 4.9l v8 and does a few run around trips in the suburbs from time to time, but have noticed the following:
- Consumption has worsened
- Idle hunts a lot more than she use to, has reached a point where it will cut off
- Black smoke from exhaust when standing still
- Distinctive smell from the exhaust
- does have a real pop/bang from time to time (not the ecu controlled )

My thoughts are that all the above points to over fuelling. My initial thoughts are possibly
- spark plugs
- some sort of sensor or plug
- fuel pump (does have a high pressure pump that was fitted a few years back)

In any case was hoping someone on the forum would have some thoughts and how to go about remedying it. Also is there someone reputable that can run diagnosing on these?


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[VinceM]

I would first advise to do a scan to see if you will pick up error codes.

What comes to mind though is incorrect Fuel/Air ratios: Biggest culprits (i) check vacuum leaks. (ii) Could be a faulty MAF or (iii) even Oxygen O2 sensors.

Worst case the fuel system (bad injectors or even a bad fuel pump).

If it were plugs you could have had a misfire of some sort.

As to who to recommend, Uncle Peter works exclusively on these type of cars (need to find his forum handle to tag).

Please run codes first to at-least have a sense of direction of where to start/look.

 

[M3boi]

I guess it would also help to understand where you are based so that we can give recommendations.

 

[Peter@AEW]

Vanos
Vanos solenoids
Catalytic Converters
On diagnostics you are likely to see
Vanos function bank 1 intake or bank 2 intake.
Also 18/100 is the norm depending on how enthusiastic you are on the throttle

 

[AshG108]

@Peter@AEW - Uncle Peter, can you help here possibly?

Nevermind, Uncle Peter already posted as I posted this.

 

[MoeM2]

Vanos
Vanos solenoids
Catalytic Converters
On diagnostics you are likely to see
Vanos function bank 1 intake or bank 2 intake.
Also 18/100 is the norm depending on how enthusiastic you are on the throttle

Thanks Peter@aew need to run diagnostics and take it from there. Any ideas where I can do that (I’m based in Randburg)

Consumption was 18/100, now closer to 25/100


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[MoeM2]

I guess it would also help to understand where you are based so that we can give recommendations.

Good point - based in Randburg


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[AshG108]

Good point - based in Randburg


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Mo - you can check Ally at XFlow performance in Strydom park for a diagnostics, he has Ista as well as other diagnostic tools that work across BMWs. He works in M5s quite a bit as well of if Juvan from @Xcede Performance is around our area (and not at the Linbro shop), you can check with him too if he can scan the car. I can whatsapp both the guys numbers to you, Juvan is closer to Sandton after hours too.

Not sure if @Peter@AEW also has tools (i am sure he does but he is also down the road from me the last I went to him) so he is also close by of he offers the services as well (I hope I am not speaking out of turn here for Peter).

 

[Peter@AEW]

Thanks Peter@aew need to run diagnostics and take it from there. Any ideas where I can do that (I’m based in Randburg)

Consumption was 18/100, now closer to 25/100


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I am in Kensington B near Goldwagen.
If you are so inclined you are welcome to send me a pm and we can take it from there.

 

[MoeM2]

I am in Kensington B near Goldwagen.
If you are so inclined you are welcome to send me a pm and we can take it from there.

Thanks Peter. Will be in touch


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