Cutting out...

It starts fine, it will idle ok and I can move off the drive down to the main road and its still ok.
I then travel say half a mile, approaching the traffic lights, clutch in, throttle off to change down a gear and revs fall to zero.

The thing is it doesnt occur all the time only some of the time.
If I coast to a halt its ok and once I've stopped it will idle fine, and whilst stopped if I touch the throttle its fine i.e. it doesnt die.
It's as though the sudden fright of the car still moving with no throttle kills the engine.

If this idle valve is faulty could it sticking on / off ?
Is it an expensive item ?

I don't think the ISCV ever shuts completely so it shouldnt stall. You can try disconnecting it and see if the fault is still there.

There is a cold start temperature switch (located on the left hand side of the thermostat), have you tried replacing that?

Mine wouldn't idle properly and stalled from cold until i replaced that. Think it cost less than £20 from Renault....

You got it cheap!

The sensor on the left hand side of the thermostat is the coolant temperature sensor for the ecu, and this controls the fuel injector pulse width depending on engine temperature. It is £47+VAT from Renault.

With a dodgy sensor, the ecu defaults to a reading of 66degrees, so cold starting is difficult and it will stall quite often when cold.

There is a cold start temperature switch (located on the left hand side of the thermostat), have you tried replacing that?

Mine wouldn't idle properly and stalled from cold until i replaced that. Think it cost less than £20 from Renault....

You got it cheap!

I knew you'd say that

[BIG_MVS]

I replaced my coolant temp sensor recently in the quest to resolve my cutting out problem and it cost £47 plus VAT. This wasn't faulty as it turned out so I have a spare you could try if you wanted to?

Cheers,

Martin

I replaced my coolant temp sensor recently in the quest to resolve my cutting out problem and it cost £47 plus VAT. This wasn't faulty as it turned out so I have a spare you could try if you wanted to?

Cheers,

Martin

Thanks, but I dont believe its this sensor causing the problem.
I'm tempted to disconnect it and see what happens - though I'm not sure what to expect i.e. once is disconnected does that it's always open ? or is it normally open but shut off when cold ? Any information on how it operates would be good.

Thanks,

Paul.

If you disconnect, you'll get a yellow diagnostic light on permanetly and the engine management system will default to thinking that the engine is at 80 degrees C. It will adjust the fuelling accordingly (i.e. reduce the amount it meters out) and thus you will find that your car will probably turn for a good while before firing up and then refuse to idle for a few minutes unless you keep the revs up manually. Once warmed up, you'll not notice much difference to normal.

The sensor is a thermistor, giving differing resistances for differing temperatures and thus varying the voltage that is sent back to the EMS. You can check the sensor by testing its resistance when cold and when the engine is hot. Not sure what the values should be as my angine management book is out on loan. An open circuit will result in the diagnostic light coming on but if the sensor is giving out an acceptible reading but just wrong - the EMS will not give any warning but will just accept that the engine is at whatever temperature the sensor tells it.

Andrew,
I think your referring to disconnecting a sensor. I'm talking about disconnecting the Speed Control Valve, I'd like to know if when its cold it should be shut or open ? I believe mine is probably not operating 100% all the time.
As this looks like a bypass valve I'm guessing it should be open when cold and nearly shut when hot but I'd like some reassurance?
Maybe mine is not clicking open enough to avoid the engine dying when on the move.

OK - no idea what happens if you disconnect the ISCV but can guess!

Again, from reading my Haynes Engine Management System book (did I not copy you the relevant Renix pages?) there are different types available - one type "pulses" open and shut at varying speeds to let more or less air through and control idle speed, the other is motor driven and can basically open or close a valve by varying amounts to control air flow and thus idle speed. Not sure which type the GTA has (think it might be motor driven) but my best guess at what would happen with each type if disconnected is as follows:

Pulse type - would not open and thus car would not idle

Motor type - would stay put where it was when disconnected so might allow the car to idle for a bit but would not be able to react to any changes in engine speed and thus would probably quickly lose idle and stall.

Car is up on the ramps at the moment and we have found that there is no power to the fuel pump at the front of the car - could well be the problem!!! Can anyone tell me where the wires are fed from and if they run through a fuse???

If your detective powers and luck are good, a quick look at the GTA wiring diagram "might" give the answer?
I don't think it is downloadable, but others will be able to scan and send some pages to you. Good luck Ben, well spotted.

Ben, look at your post at the top of page 5.......

....if you had only got to the next step on the list!

You know its going to work now though...

Tell me about it!!!! When i started the 'project' i knew the front pump was working fine, as i had problems with the rear pump when i put the engine back in. It must have gone shortly after that, as the cutting out problem started a few drives after the thing was on the road. Something stupid - as we said all along! I drove it back from Goole this afternoon and all was well, still keeping my fingers crossed, but it all makes sense....

Shhhhhhhhhhhhh everybody ..........A moments silence please .

[BIG_MVS]

What did you do to fix the front fuel pump Ben?, I'm hoping this is whats wrong with mine

It was just the wiring, so new feeds from other areas were all that was needed. Still going strong though!!!!