2.1td 1998 xantia Self Revving

[KP]

My dads xantia for some reason on startup will rev upto about 1500 rpm as if the throttle is being blipped every now and again, and has also done this twice so far when rolling upto a junction he has been slowing down for, needless to say the slowing down ones are the most concerning issues at present.

Now i think there is an air sensor blocked at some point that maybe sense boost level or such like that just needs cleaning out.

im pretty sure the EGR valve is already discconnected but i can make sure of this if needed. any advice is most welcomed.

PS its due for a cambelt and water pump before summer comes along as well

[CitroJim]

This is often caued by air in the fuel lines. Being a Lucas pump, it'll never make it hard to start but air will wreak havoc with the operation of the hydraulic servos in the pump, one of which acts as the throttle.

You can see how air can upset the thriottle. have you ever noticed that when you stop a 2.1TD it is not instant like a 1.9TD and speeds up slightly before stopping...

Go through all the same checks as you would with a Bosch equipped 1.9TD to find where the air is getting in, not forgetting the leak-off pipes.

It's urgent as bad air leaks can cause an uncontrolled runaway.

If your dad's is anything like my 2.1, most of the fuel lines downwind of the primer bulb are translucent, making air easy to spot.