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Mike, Technician
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Satisfied Customers: 39198
Experience:  Tech Expert
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At low revs - 25 to 35 mph - the engine fault light comes on:

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At low revs - 25 to 35 mph - the engine fault light comes on: the fuel injection power is reduced. A loss of a little power but other than this there is nothing wrong. When the engine is switched off then switch back on (no need to allow cooling down or otherwise - it can be switched back on immediately) the engine 're-sets' and car performance is normal.
This may happen once a month or twice a day! Garage/s have 'connected up their monitors and tested for faults' and can find no apparent reason.
Any suggestions please?
Hello and Welcome -

My name is ***** ***** Im happy to help you with this..

I need to ask a couple of things first though..

Can you give me the cars Full reg so that I can ID its management system and engine size / type accurately -

What mileage does the car have?

What is its service / recent repair history? when was the engine last serviced..?

The garage - what type is it ? Renault dealer etc ?

There has to be fault codes for this issue - what has the garage said on this?

Do you get any excess smoke when this happens?

The fault light you get on - please describe it for me---

Kind Rgds, MIKE...................................

Customer: replied 3 years ago.

111000 ex08kvk full service history: recently serviced. Last Aug 2013 similar problem. Diesel injection 'specialists' after 'looking at it for 3 days' fitted a afi switch - the control switch for the injection flow I am led to believe! It has helped over the last 8 months until the return of summer heat but did not fully resolve. (They left the cruise control and speed limiter not working - it was before they had the vehicle - but 'claimed it was not related as they had not done anything that would affect such - as cc and sp is not essential and I depend on the car constantly I did not pursue!) The recent very warm weather, similar to this time last year seems to have increased the frequency and as such, I have again returned the car to the garage to be looked at: Not sure what to believe now as initially this the 4th time of retuning it to them - they said the fuel tank would also need to be replaced and the fuel injectors need to be removed and sent off for specialist testing: quoted an enormous bill - which when I queried as the car is still within 12 guarantee for last 'repair' they then 'changed the quote' to claim that the fuel pump needs replacing and diesel cleaned out of the whole system as there is apparently 'iron type filing' traces in the diesel! After having 'tested the car' yet again over 3 days - as I insisted that they actually drive test it rather than just on a monitor: they have fitted again a new filter and said I should return it to them in 3-4 weeks so they can examine the filter!

Hope the above gives full background to assist. I believe it was an afi switch they fitted.

Hello again

Thank you for your reply and further info...

This indeed does all add up .. Im afraid what you are experiencing is a common fault / or issue with these systems - fuelling systems..
What they are doing now in fitting the new filter and asking you to run it for a time then go back and they check the filter is indeed for filings in the filter - this will tell them if your pump is failing..

What happens to explain is , these pumps dont have bearings but rather the motor in itself is a brass construction - lubricated internally it spins of course but when they start to fail, the brass "shaving" / filings come through the system..

So one you get a gradual loss of pressure from the pump over time as this is happening and two, you get the filings come through to the filter. If the filings get last the filter and into the injectors , you then have to have those attended also...

Of course with all this happening you get the driveability faults... In the early days you will get what you have - at the speeds you outline - and as it goes on / gets worse, then it will get so it wont drive at all... This can get very expensive - depending on how widespread the filings get in the system...

Now - this all assumes that indeed you are getting the filings - and it takes five mins to check - so I would ask them to show you there and then... again - if they are there it will be obvious - they show up as brass coloured shavings quite clearly... If they are not there - dont let them dupe you - you have a different fault.

If thats the case, you then need in depth diagnostics doing on the system via the OBD socket... With the absence of filings - I would suggest to have that done by a dealer... Its possible you have software issue then in the Ecu ( main computer ) and apart from anything else, they can do that for you - this very often is done to cure such driveability issues -
Any other issues / faults with the likes of fuel injection / injector / sensor / switching issues etc will show up by way of fault codes on the diagnostic..

So given what you have outlined - that as above is the way to progress / work forward on this one..

Im very pleased to have helped you - Do let me know if you need anything more --

*** Meantime - - >>>> Please do click on the "OK/ Excellent ratings" for me - Thank you in advance for that...

You can and are most welcome to get back to me anytime you might need - clicking the OK ratings does not close you out at all..

Kind Rgds, MIKE.

Customer: replied 3 years ago.

Thank you for this - they have claimed however it is 'silvery' filings. Which does not match your description of brass coloured: could the fuel tank lining be a silver steel colour and break down?

PS the dealer monitor did not reveal anything either!

HI again -

Thank you for your reply.... No they are more brass coloured - This is a common problem as I mentioned with these diesel systems.... Its nothing to do with the tank or its lining no.

I wasn't aware you have had a dealer look at it - but I would progress as above - espeically as you are working with them under the warranty... IF they do not cure it for some reason, I would do as I suggested - as time has gone on - the problem may well show up on diagnostic testing now... but again - you are stuck with them really at least for a time under that warranty - so you need to progress as above ... If they are a decent diesel specialist, they will get this sorted for you - again - its a common / known issue with this type of system...

I hope that helps/ clarifies for you - with all that you have outlined, that is the trouble you are having...

You are welcome to come back to me anytime should you need -

.... For now- Please do click on the "OK ratings" for me now at this point - Thank you in advance...

Kind Rgds, MIKE.

Mike and other Car Specialists are ready to help you
Customer: replied 3 years ago.

Thank you I will pursue along the lines you suggest on Monday and see what they say

No problem at all - Im glad to have helped..

Thank you for doing the ratings and the bonus too - thats very kind and is greatly appreciated - Thank you..

I hope things do go ok for you...

You know where I am if there is ever anything else...

All the very best to you -- Kind Rgds,. MIKE.