Renault Scenic - Loss of power

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Sun 17 Aug 2014 22:19
Renault Scenic - Loss of power - stew52

I hope somebody can help me with an ongoing problem with my car which has started intermittently losing power. It is a RENAULT MEGANE SCENIC 1.9 DCI Feb-2003- 52 PLATE and done 115,000 MILES.

The initial problem occurred about 4 months ago as I was going up a hill on the motorway. When I changed down from 5th to 4th to gain more speed whilst overtaking a lorry I had been stuck behind, the car lost all power , but didn’t stall and I immediately pulled over to the hard shoulder. The engine management light had come on but then went off and the car was still ticking over. Having checked everything looked okay under the bonnet and sounded normal, I re-joined the motorway and drove the remaining 90 miles without further problems. The next time it occurred was 4 months later on a hot day as I pulled away from a roundabout onto a dual carriageway. All power was lost as I accelerated up from 3rd to 4th gear. As soon as I took my foot off the accelerator the power came back. However, half a mile down the road as I accelerated a little more to overtake a vehicle, I again temporarily lost power. It recovered again and I drove the car to the garage without further incident. It has been there ever since as my ex-Renault mechanic hasn’t been able to find the cause. All the different parts mentioned below have been changed or checked.

Now each time the car is first driven from cold it will cut out at 3500rpm, but once heated up, it will not rev past 2500 rpm without the revs dropping completely. Also recently, my mechanic found that the car having had the sun on the bonnet for a morning, he could then get in to start the car and find that immediately it would only rev to 2200/2500revs before cutting out to tick over speed.

The car had a major service at 113,000 and timing and auxiliary belts changed at 104,000. The turbo whistles but has been doing this since August 2011 but otherwise functions normally.

The car has had a CLIP diagnostic test which revealed incoherence between cam and crankshaft sensors. Both these have been checked and changed without effect.

The EGR valve was checked and found to be clear and working ok

MAF meter was replaced with no effect.

Timing belt has again been checked and found to be correct.

Finally, a replacement ECU unit has been fitted – but this also has made no difference.

My ex-Renault mechanic and all his contacts have run out of ideas. Has anyone any thoughts or possible suggestions please? I am desperate!

Look forward to receiving any help and advice. Many thanks.

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Mon 18 Aug 2014 10:30
Renault Scenic - Loss of power - Peter.N.

Don't know much about renault engines but this sort of problem on PSA engines can be caused by the pressure regulator on the HP pumps filter becoming obstructed.

A diesel specialist would be the place to take it rather than a garage, they usually know what they are doing.

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Mon 18 Aug 2014 14:37
Renault Scenic - Loss of power - dieselnut

Most diesels from the early 2000's onwards use variable vane turbo's & these have a common habit of the vanes getting stuck in the maximum pressure position, as that is where they operate for 90% of use. The ECU then detects overpresure & puts the engine into reduced power to protect itself.

The vane mechanism becomes stuck with carbon that gets past the seals & cloggs the mechanism as the miles pile on. It may not be your problem but a good chance it is.

You really need someone with live diagnostics who can look at various parameters from the ECU while the car is being driven, especially if you can replicate the problem easily.

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Mon 18 Aug 2014 15:33
Renault Scenic - Loss of power - bathtub tom

>>The car has had a CLIP diagnostic test which revealed incoherence between cam and crankshaft sensors.

That would indicate to me a timing belt problem and as that would appear to be the only error code present, that's where I would start.

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Fri 22 Aug 2014 20:48
Renault Scenic - Loss of power - stew52

Hi Tom, Cam belt was changed a year ago. The mechanic thought it mya be kinked but checked it out and found nothing amiss. Cheers.

Stew

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Fri 22 Aug 2014 20:41
Renault Scenic - Loss of power - stew52

Thanks very much everyone for taking time to put forward your helpful suggestions.

I will post any successful results.

Stew

Edited by stew52 on 22/08/2014 at 20:45

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Fri 22 Aug 2014 20:40
Renault Scenic - Loss of power - stew52

Thanks very much for your help and suggestion.

Stew

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Mon 18 Aug 2014 17:53
Renault Scenic - Loss of power - Micky-BO

To my way of thinking this type of problem could be down to fuel pressure being borderline when diesel is cold it's thick & heavy when warm it thins out. The fuel pressure at cold & warm should be tanken Hth Regards Mickeybo

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Fri 22 Aug 2014 20:56
Renault Scenic - Loss of power - stew52

Many thanks Mickeybo. This sounds promising.

Could this be related to the fuel priming pump, if my car even has one?

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Sat 30 Aug 2014 18:47
Renault Scenic - Loss of power - stew52

Hi All,

Just to let you know got there in the end by taking it to Renault.

The problem has been solved and was, as some had suggested, the need for a genuine Renault tdc sensor and loom. Notes on service sheet stated:
Carry out clip diagnostic test 2 faults present strip out computer and sensors scuttle to access earth to cam sensor checked all 3 for resistance ok checked signal wires to tdc sensor high resistance checked found sensor weak signal Replace tdc and loom reprogramme injection computer Parts replaced : R8201040861, R8200673202 and R8200789528 all renewed. Thanks again for taking time to help. Happy motoring.
Stewart

Edited by stew52 on 30/08/2014 at 18:50

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