Saxo 1.5D diesel injection problem

[ovidiu]

Hi everyone,

I drive a Citroen Saxo 1.5 42Kw (VJX engine) 2001, having 117.400km so far. Oil and air,fuel,oil filters have been exchanged every year or maxium 10.000km.
This winter some problems with injection occurred and no workshop could fix them so far: after starting engine, the smoke is a blue-gray color with weird smell until the engine is warm when everything is normal.
The injectors have been verified/cleaned, injection pump verified, some EGR issues fixed, but the car behaves the same until engine is warm.
ODB scan returns only this error: P1200 diesel high pressure monitoring. maximum pressure exceeded.
Additionally, on the injection pump, there is a black connector for "advance" and when this connector is unplugged the engine runs perfect, but the "engine malfunction" light is on and air condition is not working anymore.
Does anyone know the cause of P1200 error and where to look at ? Thank you!

Regards,
Ovidiu

[welshpug]

injection advance solenoid probably not working correctly.

[ovidiu]

Thank you! I also got some hints about air getting into the fuel pipes above fuel filter, causing similar behavior. Basically, we verified if there are air bubbles in fuel pipes before injection pump. I'm thinking that problems started very close after filters/oil have been changed and it makes sense to check.
I will let you know what was the problem if I can fix it.

[Aly]

PM MartinObviously he knows everything about this.

[MartinObviously]

Originally Posted by welshpug

injection advance solenoid probably not working correctly.

The TUD5 runs normal when the advance solenoid is broken. I have first hand experience of this


Ovidiu:

I think your air conditioning is an unrelated problem to the engine.

When the engine is first started, your engine misfires and produces a lot of smoke?

I have the same problem with my 2001 TUD5

When you unplug the advance solenoid it runs almost perfect but a bit noisier? (little bit of knock)

I still haven't investigated it fully, I suggest you drive the car with the advance unplugged in the meantime. I have been unable to determine if the fuel pump is at fault, or the ECU/wiring loom.

I shall hook up my Oscilloscope to my engine loom (for the advance) and see what it's doing and I'll let you know.


Here's a video of how mine was, please excuse the title! lol


This was a switch in the cabin directly wired to the advance, for diagnosing the problem. is this the kind of smoke you are seeing?

[ovidiu]

Hello Martin,

Thanks for your quick answer.

Originally Posted by MartinObviously

The TUD5 runs normal when the advance solenoid is broken. I have first hand experience of this



Ovidiu:

I think your air conditioning is an unrelated problem to the engine.

When the engine is first started, your engine misfires and produces a lot of smoke?

Right. Until the water temperature is probably around 90C and engine is warm.

I have the same problem with my 2001 TUD5

When you unplug the advance solenoid it runs almost perfect but a bit noisier? (little bit of knock)

Right. When I unplug the advance solenoid everything is ok, except "engine malfunction" is on + air conditioning issues that can be related to the wiring troubleshooted

I still haven't investigated it fully, I suggest you drive the car with the advance unplugged in the meantime. I have been unable to determine if the fuel pump is at fault, or the ECU/wiring loom.

In my case is not an ECU issue, since everything related to wiring,ECU and EGR has been troubleshooted/changed.

I shall hook up my Oscilloscope to my engine loom (for the advance) and see what it's doing and I'll let you know.


Here's a video of how mine was, please excuse the title! lol

Diesel anti lag - YouTube

This was a switch in the cabin directly wired to the advance, for diagnosing the problem. is this the kind of smoke you are seeing?

Exactly the same smoke I see when is cold outside.

[ovidiu]

The injection pump has been verified on professional bank (pretty expensive) and they claim everything is ok. Not sure if they really verify the advance solenoid.
Btw, someone with a similar issue (after changing all filters) found some weak o-rings between fuel filter and thermostat, that were allowing air to enter in the fuel pipes.

[MartinObviously]

Yes getting the fuel pump checked is very expensive. I've not had to do that yet.

It's definitely something to do with the advance that is causing it. When it is plugged in, it smokes badly because the timing is being fully retarded. Sometimes this can make the car hard to start as well?

For Controlling the advance, I am unsure if it is 12 volt pulses, or a variable voltage. (it's only got 2 pins sure it can't be complicated, haha! )

When you unplug it, the spring pushes the solenoid to fully advance position, so it runs well.

As for the high pressure code (p1200), as far as I can see in my TUD5 service manual, there is no pressure sensor? which is confusing me. I must read further!

I'll go to my garage this evening and have a good look.

[mihilow]

Do you have a Bosch pump or Lucas ?maybe it's somthing stupid like some rubber on pump or somthing like that ,might be good to take it to the Bosch mechanic to chek it out

[MartinObviously]

Originally Posted by mihilow

Do you have a Bosch pump or Lucas ?maybe it's somthing stupid like some rubber on pump or somthing like that ,might be good to take it to the Bosch mechanic to chek it out

I'm sure all of them after 2001 are Bosch.

But he said his advance was a black connector, so it could be a Lucas. I've never seen an ECU Lucas before.

The Advance on my Bosch pump is Blue connector.

[ovidiu]

It's a Bosch pump.

[ovidiu]

Any update ? Did you check fuel pipes after fuel filter ?

[MartinObviously]

All my fuel lines are okay. injectors are okay as well.

I can't work it out

I'm not taking the fuel pump apart i'm gonna leave it. sorry I can't help any more