Loud Knocking Xantia 1.9td Lexia fault update - SUCCESS

Post by **RichardW** » 22 Jul 2010, 22:40

The usual fault on these is failure of the needle lift sensor in No 3 injector - this throws the pump into full advance which makes it run like a bag of spanners.

Post by **Peter.N.** » 22 Jul 2010, 22:44

I don't think it can be that, I suggested that in the first place

DickieG · Post by **DickieG** » 22 Jul 2010, 22:48

Your best bet is to get the car connected up to a Lexia as an actuator test can be carried out to test whether the pump advance is working.

Have you tried disconnecting the vacuum pipe running to the pump cold start mechanism from the solenoid end? (located on the bulkhead)

shaunlfc1 · Post by **shaunlfc1** » 23 Jul 2010, 10:30

I havent tried that yet.

The garage found the error code 144 (Injection Begin) via their SNAP ON gizmo, which is a faulty Electronic cold start solenoid.

But I've since spoken to a Diesel Pump specialist and they said that its so rare for those solenoids to fail its likely to be the sensor on the injector or the crank sensor which also talks to it.

So which injector/cylinder will I find this sensor/wire and if I disconnect it should it shut down the cold start and run normal again?

Thanks all for your help!

Shaun

MikeT · Post by **MikeT** » 23 Jul 2010, 11:28

Injection begin sounds like it's the lift sensor at fault. That makes more sense and does fit your symptoms. PSA count the cylinders from the gearbox end and you need to seek injector number three. It's the only one with an electrical connection.

shaunlfc1 · Post by **shaunlfc1** » 23 Jul 2010, 20:41

Evening all,

After spending some time on the phone to the diesel pump specialists and diesel experts at work, I finally got home from work and had a quick investigation and a play with the car.

I located the sensor on both no:3 injector and the crankshaft sensor and traced the wires until I came to connectors which I then did the following:

With the engine running I disconnected the Injector sensor from the pump by splitting it at the connector and the result was no change at all in the engine. I repeated this a couple of times but quickly connecting and disconnecting the connectors to see if I could sense any change in the engine note, which there was but you had to really really listen to it!

I was not expecting this at all as the pump specialist said that by removing the feed from the Injector sensor it would cause the cold start solenoid to go to maximum advance and the loud knocking would increase in frequency and be very noticeable, and to get the opposite effect to shut the solenoid closed so in theory to stop the horrible noise, would be too put a 12v feed directly onto the pins of the solenoid and this would close it and hopefully make the engine run smooth again providing the solenoid of course is not faulty and working fine!

So with no effect from disconnecting the injector sensor, I reconnected it and moved onto the crank sensor. Still with the engine running I disconnected this sensor and once again this made no differance in the way the engine sounded, but the K-light on the dash was now out. So with the crank sensor disconnected I gambled and re-disconnected the injector sensor and Viola the pump went to full advance and the existing horrible noise doubled in frequency and made even more noise. As to prove a point I again repeatedly connected and disconnected the injector sensor a few times and every time it disconnected the noise would increase tenfold and sound like it was at maximum advance.

From this I think the solenoid is working but is it working 100%?

Or is the injector sensor faulty and its only giving half a signal for it only to respond if the ECU/Pump is NOT getting a signal from the crank sensor? Because when the crank sensor is connected, disconnecting the injector sensor has no effect!?

Right then I hope that all makes sense, I feel I've taken half a step forward, but not sure what direction to take now?

Any ideas people?!

Thanks again for your help, be great so far!

Cheers,

Shaun

shaunlfc1 · Post by **shaunlfc1** » 26 Jul 2010, 19:57

Right hopefully some good news..... drained oil tonight using a sive into a clean container and no sign of what could be the remains of the big end bearings and the oil seems contamination free.

So its looking like ive gotta source a replacement injector no. 3, any ideas?

Cheers again

Post by **KennyW** » 27 Jul 2010, 16:59

Shaun,

I'm in a similair position as you, I think it's my injector no 3 with sensor.

if you have a good diesel repair outfit they can clean up and test and repair lift needle if requried.

i have phoned they recommended company in my area and the total cost for 4 injectors cleaned and refurbished is approx £140 including VAT.

I think this is a reasonable price.

Kenny

shaunlfc1 · Post by **shaunlfc1** » 01 Aug 2010, 16:16

Update:

Right with my multi-meter in hand I get 12v at the end of the injector sensor connector from the ECU and at the fuel pump/cold start solenoid connector from the ECU, but the connector at the crank sensor end I am only getting 2.5v. Tried it with engine on, engine off and injector sensor connected/disconnected, but still only 2.5v at the cranks sensor end from the ECU????

Is this the ECU being in a locked state and needing reset with a Lexia?

Also today I managed to get a 12v feed from the battery onto the cold start solenoid and SUCCESS the engine ran fine with no noise, so this proves the cold start solenoid is working and at least I can get it into full retard!

I will contact my local lexia holder and see what we can do.

So can anyone confirm that the ECU does need resetting?

Cheers all much appreciated!

Shaun

Post by **CitroJim** » 01 Aug 2010, 18:40

Shaun, what exactly do you mean by cold start solenoid. Do you mean the electrovalve in the base of the pump? If so, then applying 12v directly to it is a test, but not a good one. It should be fed a diet of pulses from the ECU (a square wave of varying mark:space ratio or Pulse With Modulation) to vary the timing under ECU control.

You've at least proved that bit is working but you've not located the fault.

A Lexia session in skilled hands is now essential to complete the diagnosis and nail the problem.

ECUs don't lock up and don't generally need resetting. They are also very reliable generally.

Another test: If you disconnect your needle lift sensor (on No.3 injector) does the tacho keep working? If it stops the TDC sensor is duff. Prove this by reconnecting the NL sensor and disconnecting the TDC sensor. If the NL sensor is OK, the tacho will keep working. Basically, the tacho will work from either sensor even if one is not working.

shaunlfc1 · Post by **shaunlfc1** » 01 Aug 2010, 19:04

Yes the electro valve in the base of the pump, a Bosch Diesel Speciailist told me thats the only way to test the solenoid and send it into full retard.

But did say not to use this as a fix and run the car like it, its just a TEST!

I do have a scenario that has caused the Rev counter needle to spin around to way past max and its now stuck there. That happened on one failed start of the car the speedo and rev counter needle went mad and the car didnt start. Cannot remember what sensors we had disconnected or connected.

We reverted back to default, reconnected everything, using jump leads the car fired back up first time but rev counter still stuck past max.

Is there a reason for only getting 2.5v at the end of of the connector from the ECU to the crank sensor? All the wires check out with a multimeter for continuity?!

Cheers again,

Shaun

Post by **CitroJim** » 01 Aug 2010, 19:09

The rev counter can be sorted by nudging the needle back Shaun. There have been a few threads on the methods. A piece of stiff wire carefully threaded into the trip reset knob hole will do the trick...

Yes, 2.5V is what I'd expect to see. I can only guess at the electronics in the ECU that read the sensor but it sounds about right to me.

A better way to see what is going on from the sensors and what is going to the timing electrovalve is to use an oscilloscope.

shaunlfc1 · Post by **shaunlfc1** » 01 Aug 2010, 19:14

12v everywhere else apart from there?

So if a member off here cant help me with a Lexia which I am hoping as already PM'd a member, apart from buying one will a Citroen dealership have one, and if so can any ideas what they would charge for this?

Would you agree it now sounds like the Crank sensor? As the working 2nd hand No:3 injector when disconnected sends the pump into full advance now!

Thanks again for your help....

Post by **CitroJim** » 01 Aug 2010, 19:22

Get your tacho needle sorted Shaun and all should be revealed.

A Citroen garage will have a Lexia but that's not to say the operator will understand properly what he is seeing. Diesel stuff is a closed book to most average garagists. Hence why diesel specialists abound.

You're much better off finding one of us off here to do the Lexia bit. Even if the person is not a dieselist, at least one of us who is can explain what you should be seeing.

shaunlfc1 · Post by **shaunlfc1** » 02 Aug 2010, 21:05

Hi all,

Latest installment. ........ new crank sensor installed tonight by still no change in engine noise, but Rev counter back working. Disconnecting either sensor now sends pump into full advance.

So its looking like full diagnostics now with a Lexis or at Bosch specialists, as I'm all out of ideas !

Cheers,

Shaun