Renault Scenic DCi 2002 - Starting problems - EGR Valve?

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Sat 28 May 2011 00:20
Renault Scenic DCi 2002 - Starting problems - EGR Valve? - Amasa

Earlier today my wife 'phoned to say that her 02 Scenic DCi had broken down (luckily not far from our house), apparently the engine had simply cut out and would not restart. I tried to start the car, the starter was spining OK, battery had plenty of power, half a tank of diesel, but no joy although once or twice it sounded like it tried to fire up. I noticed the engine management light, ABS and stop lights were illuminated when the ignition was on.

Called Green Flag, chap plugged tester in and then proceeded to remove the EGR valve. He cleaned the valve a bit, put it back in and the car started, he increased the RPMs and all looked good, no smoke, no odd noises. He switched the engine off and tried to re-start, but the car was having none of it. He tried the tester again and informed me there was an EGR fault, get a new one he tells me and all will be fine, and proceeds to recover the car home.

Once home, I have the EGR valve out and give it a really good clean, 'plunger' seemed to be moving freely. I put the valve back and the car re-started and idled happily, although the engine management, stop and ABS lamps remained illuminated. Swtiched off and tried to re-start, again the car failed to start.

Left the car for 2 hours, tried again and it fired up, again warning lamps illuminated. Turned ignition off and tried to restart, but yet again it wouldn't. An hour later tried again and exactly the same behaviour, fired 1st time, idled OK, but once switched off would not re-start.

Could it really be the EGR valve causing this ? Very, very grateful for any ideas.

Edited by Amasa on 28/05/2011 at 00:21

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Sat 28 May 2011 01:36
Renault Scenic DCi 2002 - Starting problems - EGR Valve? - unthrottled

No. If the engine isn't firing it shouldn't matter if the EGr valve is open or closed.

Has the fuel filter been changed recently. If it hasn't been fitted very well, air could be getting in which can cause hot starting problems.

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Sat 28 May 2011 01:54
Renault Scenic DCi 2002 - Starting problems - EGR Valve? - Amasa

Thanks for your reply. Fuel filter was changed 6 months ago, would have thought if there was a fuel problem or air leak it would always struggle to start, then run rough?. Got to be something electrical (sensor?) to trigger the engine management and stop lights on the dash. Could it be the electrical part of the EGR failed?

Just don't understand why it will start, then when switched off refuse to start again unless it's left for about 1 hour.

When it is running it idles well, no fluctuation in revs, no smoke, no whistles or vibration.

Edited by Amasa on 28/05/2011 at 01:57

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Sat 28 May 2011 03:26
Renault Scenic DCi 2002 - Starting problems - EGR Valve? - unthrottled

Yes, but cranking speed is only about 150 RPM compared to idle speed of 900 RPM so faults can show up at cranking speed that are masked at normal running speed.

The normal 'cause' for hot starting problems is that the fuel viscosity is lower than when it is cold. Combined with low cranking speed, this can mean that any leaks will prevent the fuel rail for building up sufficient pressure. Sometimes hot starting is a symptom of a warn HP fuel pump (Let's hope not!).

You say the EML comes on-any fault codes? I'm still betting that there's insufficient pressure in the rail from a leak-either air getting in-or diesel getting out.

There's always things like crankshaft sensors, anti shudder valves sticking closed but I wouldn't have thought that the problem would be so temperature sensitive.

Still don't see how the EGR valve sticking open would cause a hot start problem-and if it was you would have a black smoke/loss of performance problem too. EGR is a bit of a bogeyman. Because it doesn't contribute to power or fuel economy, everyone hates it and blames it for all manner of engine problems that usually lie elsewhere.

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Sat 28 May 2011 10:52
Renault Scenic DCi 2002 - Starting problems - EGR Valve? - Amasa

Thanks so much for taking the trouble to reply. Car left overnight, had a look this morning, can't see any signs of fule leaks underbonnet or under car.

Started from cold 1st time, noticed that once started the engine management light very quickly swtiched off, then came back on again, along with the service and ABS lights. Idled fine, no smoke, very smooth idle. Switched off, and yet again it refused to restart so the problem manifests itself hot or cold.

Bloomin typical, was going to PX it this week - it's almost as if it knows...A pain becuse my mechanic is on holiday this week.

Would the fact that the engine management lamp briefly went out once the engine started, then came on again suggest the ECU is picking up a problem?

Eddie.

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Sat 28 May 2011 12:06
Renault Scenic DCi 2002 - Starting problems - EGR Valve? - unthrottled

How odd.

Yes, the EML isn't on for fun.Pity the mechanic is away.

I'm coming round to your way of thinking-that it is electrical, but i don't pretend to understand it!

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Sat 28 May 2011 12:16
Renault Scenic DCi 2002 - Starting problems - EGR Valve? - madf

Sounds like a sensor coil is breaking down.

Crankshaft sensor is prime candidate. When it warms up, the wires separate and silence..

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