[froggy_french]

I have searched the forums and not come across my bizarre problem anywhere.

The Scenic is a 53 plate 1.5dci with 82000 miles on the clock. I have used the advice on these forums to fix my windscreen wipers and get the clock fix from Renault for the £100.... I am therefore already endebted to these forums!!

Ordinarily, the car starts, idles and runs wonderfully. It is still pulling properly and is smooth and willing to rev etc. HOWEVER, occasionally it hiccups and carries on driving normally. It feels like a bit of muck in one of the injectors which clears itself and then all is good again.

Sadly, about once every 20 miles it hiccups and the instrument panel asks me to select neutral before coming to a halt. The engine remains running but the car will not allow it to continue. If you pull to the side of the road, take the key out, stop the engine and then restart it will start as normal and continue as normal.

My initial thoughts are that one, or more, of the injectors is on its way out and causing the "hiccup". However, does the Scenic have a management system which will cut power if it thinks an injector problem could be dangerous??

In an attempt to clean the injectors I have used one of the fuel additives but this seems like a complete waste of £8. It doesn't seem to make things worse or better!!

Any thoughts would be really appreciated before I need to take it to be diagnosed by the Renault dealers and there licence to rape and pillage!!

 

[madnoel10]

Are there any warning lights on the dash when the problem arises?

The ECU will either stop the engine or make it go to idle if it detects the fuel system is over-pressurising.
Switching of the engine will allow the pressure to drop in the fuel rail so everything resorts to normal - if you get my drift.

Sadly there are numerous possibilities for such problems such as faulty fuel pressurer sensor, faulty fuel pressure regulator, etc, etc. If it were mine the first thing I would do is to check the anti-stall switch on the clutch pedal and inspect the fuel filter for signs of water or metal filing contamination. Both these checks are cheap and although not necessarily the cause it would be worth checking if only to eliminate them as potential faults.

 

[froggy_french]

madnoel10, thank you so much for your response. I am really grateful for such a good start to my investigations. TBH we have always serviced the Scenic ourselves and it has ran wonderfully for about 50,000 miles BUT I cant ever remember replacing the fuel filter.... OOPS!!

I will let you know how we get on over the weekend... fingers crossed.... I believe the fuel filter is towards the back of the car close to the fuel tank - would that be about right???

Thanks again,

Mark

 

[froggy_french]

OOps almost forgot, only warning light tells me to select neutral as it coasts to a standstill, other than that the dials look perfecty normal!!

Thanks again.....

 

[madnoel10]

On diesel engine the fuel filter is normally within 500mm of the high pressure fuel pump - so find the feed pipe to the HP fuel pump and trace it from there.

When you remove the old fuel filter drain it's cintents into a clear glass container and let it stand overnight - then check for signs of water and contaminants - especially fine metal particles.

 

[froggy_french]

On diesel engine the fuel filter is normally within 500mm of the high pressure fuel pump - so find the feed pipe to the HP fuel pump and trace it from there.

When you remove the old fuel filter drain it's cintents into a clear glass container and let it stand overnight - then check for signs of water and contaminants - especially fine metal particles.

Well what can I say other than another massive thank you to the forums... Thanks especially for the help offered by madnoel whose input means that my scenic seems back to its normal self again.

I bought the new fuel filter and removed the front wheel drivers side and the plastics in the wheel bay. The plastics around the wheel bay are a mixture of push pin holders and 2 x screws/bolts. With the plastics removed the fiddly bit began due to the way Renault mount the filter i.e. within a bracket with two halves held together with a jubilee clip!! We ended up removing the filter from the bracket and then making a careful note of the colour coded fuel pipes. Be warned that the clips are a push fit and need the sides of the clip to be pressed in before they will come away from the filter.

Once the old one was removed the new one was positioned close to the original bracket and cable tide securely in place.... This is a lot less hassle to accomplish and will make the job easier next time!!

As the original problem was obviously related to fuel and the way the car was breathing I also decided to change the air filter whilst under the bonnet. This is a MASSIVE hassle of a job and one I will not go into here, suffice to say that I can see why Renault rub their hands together when you book a service....

The car now seems much quicker and it hasn't hiccup'd once (finger crossed)... probably because it can now breath properly again!!

Thanks again madnoel and another :d for the forums and :loser: to the Renault dealerships!!

 

[froggy_french]

After 2 weeks of faultless starting and smooth running the problem happened again at 75mph on the motorway... Just one hiccup and the engine went into "override", it was still ticking over and not dangerous at all as the power steering was still functioning as it should!! It feels weird doing 70mph with an engine that refuses to do anything but idle. Due to the "override" you can't stop and restart the engine unless stationary!!

I pulled on to the hard shoulder, stopped the engine, restarted the engine and everything was fine with the car, running and pulling well all the way to work (about a further 10 miles of commuter traffic).

This is really getting to me now and I am losing all confidence in the car.... ANY further help would be greatly appreciated...

 

[danthevan]

I'd be tempted to change the filter again. As it sorted the problem last time, it's quite possible that you have contaminated fuel in the tank still

 

[froggy_french]

Ok people a quick update to this ongoing problem....

Following a friends advice I had a diagnostic guy plug his pc into the funny little interface under the centre console. He diagnosed a faulty fuel pressure switch which does seem to stack up with everything that has been said on this thread. He reset the switch and started the engine... everything was running as sweet as a nut but the switch did return a second fail error rather quickly.

He commented on how sweet the car was running and how at tick over he would swear there was no fault whatsoever!!

Armed with this knowledge I paid my local Renault garage a visit to pick up a new switch and was told that the whole common rail bits have to be purchased and the switch is not available by itself..... Just £297 to you, sir.....

So my next question is.... does anybody know here I can source the switch by itself and if I do need to go the secondhand car breaker route, how do I identify the switch as being from the same vehicle as mine???

Does anybody think that the problem is the switch or is the diagnostic software simply flagging it up as the weakest link??

The car now goes to "failsafe" with just a beep and nothing changes in the dash to give me any clue at all about the problem or why it falls into "failsafe"

PLEASE HELP

 

[froggy_french]

FINAL POST

After much head scratching and deliberation I took the Scenic to a friends garage. He carried out another PC diagnosis and could find nothing wrong at all!! He then decided to do a leak test and found the injectors to be working perfectly with no leaks etc. Towards the end of the leak test he noticed that one injector was leaking a small amount of air. He followed the fuel line back through to the troublesome filter and noticed that although the two fuel lines appeared to be attached firmly they weren't "clicked" into place!! He clicked them in, which does require a lot of pressure, and took the scenic out with the diagnostic pc plugged in.... No errors reported and guess what?? no further problems at all... It appears that the ill fitting fuel lines were letting in a small amount of air which was triggering the sensor to cut the engine.... Thanks to everybody for their help :d