engine whine

[Jules]

Engine whine on the over run


I've had quite a few of the M47 diesels with this problem but have all been the facelift models.

Reading a few threads it's looks like resonance in the high pressure fuel lines.
Rover were looking into it before their demise so i don't think a solution was sorted.

[Roverron]

Originally Posted by smokie999

the whine is a constant from starting up goes up with the engine revs but is more audible in first and second

Is it audible under no load - ie can you hear it with the bonnet up when you rev up?
Alternator or power steering pump can whine a bit.

Ron

[Jules]

Hi Ron
Under load the whine stops, its really only on the overrun.
I have 2 facelift M47's in at present doing the same thing!

What I want to know is what did Rover BMW change in the later cars to do with the high pressure fuel lines, high pressure pump, and it's fuel regulator.
Maybe they changed the waveform from the ECU?? Who knows

It's not wear related because brand new CDTi's had this symptom

I've started a new thread but this problem which was highlighted 3 years ago on the other forums:

http://www.the75andztclub.co.uk/foru...ead.php?t=8256

[David3807]

Didnt later cars have only 1 fuel pump ??

[Roverron]

Originally Posted by julesbass

Hi Ron
Under load the whine stops, its really only on the overrun.
I have 2 facelift M47's in at present doing the same thing!

What I want to know is what did Rover BMW change in the later cars to do with the high pressure fuel lines, high pressure pump, and it's fuel regulator.
Maybe they changed the waveform from the ECU?? Who knows

It's not wear related because brand new CDTi's had this symptom

I've started a new thread but this problem which was highlighted 3 years ago on the other forums:

http://www.the75andztclub.co.uk/foru...ead.php?t=8256

I have no idea if anything was changed - nothing was that I'm aware of.
Disconnect the maf sensor - this will affect the overrun fuel cutoff and should, if you are right, alter the noise.

But maybe it is related to having no underbonnet pump and a change to the fuel supply and return plumbing in the engine bay.

(Neither the Tu3 , mafam nor Synergy make any differenece to it)

Ron

[Jules]

You are absolutely correct, but the resonance is after that
ie in the very high pressure side of the diesel pump just below the power steering pump.

This is where the electronic fuel regulator is too with a pair of wires going to it.
This is I believe where the Pulse Width Modulation PWM signal goes in form the ECU.

If some electronics buff or a remap wizard could alter the frequency of the PWM without affecting the fuel pressure regulator

I think that would be the cure

[Roverron]

Originally Posted by julesbass

You are absolutely correct, but the resonance is after that
ie in the very high pressure side of the diesel pump just below the power steering pump.

This is where the electronic fuel regulator is too with a pair of wires going to it.
This is I believe where the Pulse Width Modulation PWM signal goes in form the ECU.

If some electronics buff or a remap wizard could alter the frequency of the PWM without affecting the fuel pressure regulator

I think that would be the cure

Realistically you aren't going to be able to alter the ecu programming so I can only suggest trying to add mass to the pipes so that the pulsations are reduced by them having to move more mass. Also damping them with rubber strips.
This will be far simpler - if it works!

Ron