Xantia 2.1 Crankshaft Sensor

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

bddeazeley
Posts: 34
Joined: 20 Feb 2006, 16:33

Xantia 2.1 Crankshaft Sensor

Post by bddeazeley »

Hi There, Can anybody tell me where the crankshaft sensor is on my 1998 Xantia 2.1? I have checked the Citroen Service website by putting in my VIN number and the sensor diagram shown is different from my car. Are there variants of this model? I have a green sensor (coolant temperature I think) on the end of the cylinder block above the gearbox where the Citroen website shows the crankshaft sensor or speed sensor as it is referred to. This coolant sensor on the Citroen website appears to be mounted behind the fuel filter on the fuel heater casting whereas mine has a blanked off plug in that position. I want to change the sensor as I am experiencing an intermittent loud diesel clatter from the engine which at worst only lasts a few seconds. I had an air leak into the fuel system but I have managed to cure that after replacing some fuel pipes, the primer bulb and eventually the fuel filter housing and 'o' ring. The clatter is not as bad as it was but still happens for no apparent reason. The other symptom I have is sometimes above 3500rpm the engine sounds as if it is surging in a steady rhythmic manner but at other times it performs perfectly ok. I am presuming that I am loosing an input from a sensor so hence the reason I wish to change the crankshaft sensor .... if it has one lol. Any advice will be welcomed. Thanks, Brian.

Peter.N.
Moderating Team
Posts: 9728
Joined: 02 Apr 2005, 16:11
x 265

Re: Xantia 2.1 Crankshaft Sensor

Post by Peter.N. »

Its a bit buried under pipes and wires but you will find it at the left hand end of the head (looking from inside the car) just above the gearbox bell housing, it is about in the middle but as the engine slopes backwards its at about 1.00 o clock looking at the end. You should be able to see the connector above it so follow the wires.

Peter

User avatar
CitroJim
A very naughty boy
Posts: 41564
Joined: 30 Apr 2005, 23:33
x 1055

Re: Xantia 2.1 Crankshaft Sensor

Post by CitroJim »

Brian,

It may be the needle lift sensor on No.4 injector. they do die whereas the crank sensor is one of the most reliable sensors I know.

Is your tacho working OK?

Test the Needle Lift sensor by unplugging the black connector to it and measuring its resistance. I can't recall exactly what resistance it should read but it should not be that high and definitely not open-circuit. Unplug it with theengine runninga dn if the engine note does not change then it's a goner.

Sometimes it's just a bad connection on the plug. It can vibrate loose.

A Lexia diagnosis will shed more light...

Peter.N.
Moderating Team
Posts: 9728
Joined: 02 Apr 2005, 16:11
x 265

Re: Xantia 2.1 Crankshaft Sensor

Post by Peter.N. »

You've got the right man for an EPIC diesel now :-D

Peter

bddeazeley
Posts: 34
Joined: 20 Feb 2006, 16:33

Re: Xantia 2.1 Crankshaft Sensor

Post by bddeazeley »

Thanks for your quick response gentlemen. I have measured the needle lift sensor and it reads 105 ohms on my meter which, according to what I read is correct. I disconnected the plug connector to the needle lift sensor whilst the engine was idling and there was no noticeable reaction from the engine except when you increased the revs and the engine had a slightly more distinct metallic diesel rattle but nothing significant. The tacho works ok even when the needle lift sensor was disconnected. Again today at higher revs (above 3500) I got this rythmic diesel rattle noise as if the IP was cycling in and out of advance. On occasion I also get this rattle when I change gear from 1st to 2nd at the point I take my foot off the accelerator. A lexia session is probably the best way forward.

User avatar
CitroJim
A very naughty boy
Posts: 41564
Joined: 30 Apr 2005, 23:33
x 1055

Re: Xantia 2.1 Crankshaft Sensor

Post by CitroJim »

Peter.N. wrote:You've got the right man for an EPIC diesel now :-D
Thanks Peter :) :oops: :lol:

Good, that proves the Needle Lift Sensor is good then :-D

Yes, a next step would be a Lexia. Not to read faults but to run the pump through a series of tests, one being its ability to respond correctly to timing signals.

The EPIC pump is a full fly-by-wire design and fully electronically controlled. Timing, speed and stop functions are controlled by electrovalves inside the pump called ESOS valves. They do get leaky and the Lexia tests will be able to determine if all four valves are working correctly. The tests are:

Stop test - The engine should stop :roll:
Speed test - the pump is controlled to accelerate the engine to 3,000 rpm and hold it steady there.
Timing test - the pump is made to range from full retard to full advance and back again. It'll knock like a bag of spanners during the test!

The final test to perform on live data is to determine the pump is following live timing commands from the ECU correctly.

Air is a big problem with all EPIC pumps; they are incredibly sensitive to it so you may find your problem is still air ingress. It's always a very good idea to replace the leakoff pipes and the end blanking cap on No.1 injector which is a well-known little devil for splitting.