406oc.co.uk

occassionly when starting the engine the engine used to surge the throttle by it self, fluctuating between 1k and 2k rpm,then would stop, but when you drove away to revs used to raise to something like 5-5.5k rpm and slowly drop back to idle. although it stopped and carried on per usual. it has done this a few times i thought nothing of it and carried on as per usual.

today the car started to fluctuate the rpm ALL THE TIME, and rev very high when the clutch is depressed during a gear change. it is definately a electrical problem not the throttle cable.

when it revved very high i shut the engine off, upon trying to restart it the engine cranked over and over and over. turned the ignition off completely and back on again, it fired up first time. it has done this twice.

ive checked most the connections i can see but it still has not sorted the problem.

any help would be appreciated.

try cleaning the stepper motor

There is no stepper motor or idle air control valve on this diesel engine.

sooooo....the problem could be.....?

could be the turbo bearings on the way out maybe ?, oil gets past them and is sucked into the enging and used as fuel to rev the engine, the higher the revs get, the more oil gets past the turbo bearings so the higher the revs get and it goes round and round till the engine blows.

you could disconnect a pipe between the turbo and the engine inlet to see if oil sprays out when you rev the engine if the problem can be reproduced when the cars stationary

Is there a throttle pot on these?

Coolant temperature sensor.

When they fail the car thinlks it's colder than it is and pumps more fuel, hence high revs.

Cheers
Steve

to save me looking at the haynes, where is this sensor located?

Broomer wrote:to save me looking at the haynes, where is this sensor located?

In the end of the cylinderhead just above the bellhouseing, it's the one with a green lecy conection.
You will need to reset the ECU after changing it, do this by disconecting the battory over night.

I had very simaler with my car, search my early posts as it may help.

i have ordered the sensors and will switch them tomorrow and reset the ecu over night.
hopefully that will sort it.

cheers

Green sensor arrived to day just as I received a reply from the nuggets on ebay telling me they have the right one for my VIN no.....but that's not the one they sent me Mind you it looks the same!
-
So how does the green one come out? It hasn't got a thread on it so I presume something else keeps it in place! I haven't managed to get a decent look yet as by the time I'm home it's dark and I haven't fancied standing outside with a torch in the rain/sleet/snow.
-
i have ordered the sensors and will switch them tomorrow and reset the ecu over night.
Do I have to do this too
How?

When I replaced mine, it had a thread on it, should just come out with help of a spanner!

Ah, should have said looks the same from the outside....that'll definitely be the wrong one then!
I only had a quick look when I changed my oil last week and was sure it had a nut on it looks like their are several different types of course....bloody typical to get sent the wrong one!