Xsara II 2.0 HDI 90 Fuelling Issues

[dave_xsara]

I've only just noticed this thread.
The air temp, brake switch & evaporator faults are logged in nearly every single 2.0 HDi xsara I have ever scanned. I would regard them as 'phantom faults'.
There was a mod years ago to run a new earth to pin 3 of the MAF but I didn't find it helped any & still always came back.

Thats good to know. I couldn't see what was causing those issues.

As for P1138 - this was often cased by a poor connection on the little 3 pin connector on the fuel rail pressure sensor, if you follow the wiring for the sensor down a few inches there is a 3 pin connector (yellow from memory), its clipped onto the engine block just above the sump. Cut the connector out & solder the wires direct. If that didn't work you replaced the fuel rail pressure sensor. A typical symptom of this fault was the engine running on for a few seconds after the engine was turned off.

That fault was only logged once and has not reoccurred. At least know I know the fix if it does come back. Again, thanks.

If you need a wiring diagram I still have some original workshop manuals for the Xsara so may have a paper copy I could scan, would need your RP number to check.

That would be good thanks. I notice Marc has already replied with my RPO - thanks Marc.

[dave_xsara]

So a couple of observations:

Definitely sounds like a fuel starvation issue - either as a consequence of low pressure or an air lock for example.
I don't recall you said you actually replaced the fuel filter in this thread, if not how old is it - but if you have , did you prime the fuel system properly after fitting it? (Edit: Ignore that bit - self-bleeding on the Bosch)

Fuel filter was replaced about 1000 miles ago as part of a full service. I didn't do it myself so I can't confirm the process followed.

[RichardW]

If it's Bosch then it has an in tank fuel pump, failure of which is common, and causes the cut out symptom you saw.... Is it noisy at key on (it should run for around 10 seconds)?

[dave_xsara]

RichardW: Yes, it whirls for approx 10sec at key on.

Marc: when you say prime the fuel system, what is the process? There is no priming bulb.

[GiveMeABreak]

Scrub that Dave - it only concerns the Siemens system. On the Bosch system the bleeding of the high and low pressure fuel circuits is automatic. I'll amend my previous post.

[wheeler]

Fuel rails are notorious for throwing wobblies if the sensor alone is replaced - I know Citroen don't sell the sensor individually,preferring to supply the fuel rail complete with sensor and there is a specific warning about not separating this (whilst under warranty at least - warning of problems).

As far as 2.0 HDi Xsaras go I believe only the Siemens system fuel rail pressure sensor comes complete with the rail (even though it can be unscrewed from it), On the Bosch system the sensor is a separately available part.

I have scanned the diagram DW10 RHY 90bhp, multiplexed (but no com2000), RP no 8636 onwards & it is the single 88 way ECU plug. It is a PDF but the forum wont let me upload it?? invalid file extension?
If its the Later model with the 3 separate ECU plugs I don't have that one.

[dave_xsara]

Does anyone know if the engine idle MAF reading of 490mg/cp is correct? If it is not, would this not indicate that there is a leak somewhere which might be related?

Code: Select all

490mg/cp       = 490mg/stroke
490 x 2        = 980mg/rev
980 x 802      = 785,960mg/min
785,960 / 1000 = 785.96g/min
785.96 / 60    = 13.1g/s

According to some quick Googling g/s reading at idle should be between 2g/s and 7g/s. Allowing for some deviation due to idle value then the reported value should not be over double this range maximum, should it?
Ref: AllData MAF Sensor Testing

Interesting that the default when MAF unplugged was 535mg/cp. However, I've read that it might be a default mid range value. I've no way of confirming.

This may or may not be related to the fuel starvation issue.

[dave_xsara]

I have scanned the diagram DW10 RHY 90bhp, multiplexed (but no com2000), RP no 8636 onwards & it is the single 88 way ECU plug. It is a PDF but the forum wont let me upload it?? invalid file extension?
If its the Later model with the 3 separate ECU plugs I don't have that one.

Yes, 3 separate ECU plugs.

[wheeler]

Does anyone know if the engine idle MAF reading of 490mg/cp is correct?

I would expect to see around 500 mg/cp @ idle if the EGR valve was stuck closed or blanked off.
With the Engine warm @ idle I would expect to see around 250-300 ish mg/cp Assuming the EGR is working correctly. With the engine running if you then pull the vacuum pipe of the EGR valve you should see the reading jump up to around 500 mg/cp.

I have scanned the diagram DW10 RHY 90bhp, multiplexed (but no com2000), RP no 8636 onwards & it is the single 88 way ECU plug. It is a PDF but the forum wont let me upload it?? invalid file extension?
If its the Later model with the 3 separate ECU plugs I don't have that one.

Yes, 3 separate ECU plugs.

I do have a later one with 3 pug ECU but its full multiplexed with com2000 so wouldn't be correct.

[dave_xsara]

Would there not be a fault thrown up for a stuck EGR valve?
Its definitely not blanked - had car since new.


Edit: sensors are only on the newer EGRs so, that'll be why there is no fault logged.

[wheeler]

Would there not be a fault thrown up for a stuck EGR valve?
Its definitely not blanked - had car since new.

No, this injection system/engine will run quite happily with a blanked off EGR valve with no warnings or fault codes whatsoever.
Every car I have had in the family with this engine I blanked the EGR valve & throttle butterfly as soon as I got it to stop it choking the air inlet ports, I bought C5 years ago with a blown head gasket, when I taken the head off the air inlet ports on the inlet manifold had reduced to about the diameter of a 20p piece.
Maybe you have a vacuum issue? are you feeling suction on the EGR vac pipe? maybe the valve has seized closed, might be worth taking it out for a clean.

[dave_xsara]

Okay, I'll take it out at the weekend and give it a clean.
I've read that getting a de-coke on an older engine is a bad idea as the dislodged carbon deposits can block the galleries. So I presume any cleaning beyond the actual EGR value is not to be performed?

[GiveMeABreak]

It is a PDF but the forum wont let me upload it?? invalid file extension?
If its the Later model with the 3 separate ECU plugs I don't have that one.

You'll have to send the PDF directly to him via email as we don't allow PDFs currently for security vulnerabilities.

[GiveMeABreak]

As far as 2.0 HDi Xsaras go I believe only the Siemens system fuel rail pressure sensor comes complete with the rail (even though it can be unscrewed from it), On the Bosch system the sensor is a separately available part.

PSA only list the rail for this Bosch engine and no separate sensor.

I appreciate they can be bought separately on the aftermarket, but the point was the issues these can result in if separated.

[wheeler]

If you go to the sensors page on citroen service its listed separately part no 1920SZ but only for the Bosch system, the siemens system it comes complete with the rail.