Xsara II 2.0 HDI 90 limp mode

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RichardW
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Re: Xsara II 2.0 HDI 90 limp mode

Post by RichardW »

Can you use Diagbox rather than Lexia? You will (probably) get more info!
Clear the faults - does anything come back immediately?
My guess would be it's the TPS fault that is causing limp. Check on live data that the two signals are the same - this car might have a remote TPS with a cable pull rather than one on the pedal, a unit swap shouldn't be too dear if this is indicated which will confirm fault with the unit or the wiring...
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

My other observation now that I have looked through some of the Lexia screenshots is that the Diesel Pressure Signal is potentially misleading.

I note that on the P0190 Diesel Pressure Signal code that the Open Cycle Ratio is very high, 97.3%. It is unlikely it should be that high unless the car is under very high load and accelerating.

At idle, it is normally around 16-18%. Basically the fuel pressure regulator is told by the ECU when to open and close and it produces a square waveform on an oscilloscope (on, off, on, off, on, off) and the periodisation of that on/off cycle is what gives the percentage open cycle ratio.

Of course, it is told to open and close on the basis of the information coming from the fuel pressure sensor so the two are inextricably linked. It opens if there is insufficient pressure in the fuel rail and closes when it is sufficient. If a fault develops, then and it stays closed for longer than it should the car will cut out as the pressure in the fuel rail drops below the approx. 300 bar differential value.

Now. I am not sure where the pedal signal comes into this but if that is dropping out, then the ECU will be told that there is no load and it will no doubt just simply factor this into the equation of a variety of factors ie how long to keep the injectors open for and hence how much fuel is required which is where the MAF comes in.

I think you can safely rule out the MAF sensor for the purposes of what you are looking for at the moment because that is more likely to affect smoothness of acceleration and whether it is hesitant. It wouldn't cause the vehicle to cut out.

It seems more like your car is just shutting off.

My advice until you get this sorted is stay in the inside lane of any motorway you cannot avoid travelling on.

Where are you based as a matter of interest?
dave_xsara
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

I recently changed the HP regulator to correct hunting at idle.
Will need to see about using Diagbox - Have only every used Lexia.
MAF was recently replaced and wiring check and confirmed as okay.
The only faults that come back are those which I've been told are known ghost faults.
Clutch has been changed, not sure about a connection for wiring, will need to ask mechanic or check

TPS? - Throttle Position Sensor?
Last edited by dave_xsara on 24 Mar 2021, 00:48, edited 1 time in total.
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

Thanks for the replies. I'll see about getting diagbox on it tomorrow to see what comes up.
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

RichardW wrote:
22 Mar 2021, 15:05
Can you use Diagbox rather than Lexia? You will (probably) get more info!
Diagbox give me option of Lexia or ScanTool.
the only faults that come back I've been told are phantom faults.
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

Also noticed recently that the car is idling at around 1100-1200rpm, instead of around 800rpm as normal.
Car isn't driven as much as normal with Covid, so I'm not sure if this returns to a low level after engine has warmed up.
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

dave_xsara wrote:
26 Mar 2021, 13:11
Also noticed recently that the car is idling at around 1100-1200rpm, instead of around 800rpm as normal.
Car isn't driven as much as normal with Covid, so I'm not sure if this returns to a low level after engine has warmed up.
Did you read my posts?
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

Rhothgar wrote:
26 Mar 2021, 13:24
dave_xsara wrote:
26 Mar 2021, 13:11
Also noticed recently that the car is idling at around 1100-1200rpm, instead of around 800rpm as normal.
Car isn't driven as much as normal with Covid, so I'm not sure if this returns to a low level after engine has warmed up.
Did you read my posts?
Yes, I've loaned out my multimeter so waiting it to be returned. This behaviour has been happening for a long time. The high idle itself is only a recent phenomenon - I missed the part about 1200rpm being emergency mode.
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

dave_xsara wrote:
26 Mar 2021, 13:33
Rhothgar wrote:
26 Mar 2021, 13:24
dave_xsara wrote:
26 Mar 2021, 13:11
Also noticed recently that the car is idling at around 1100-1200rpm, instead of around 800rpm as normal.
Car isn't driven as much as normal with Covid, so I'm not sure if this returns to a low level after engine has warmed up.
Did you read my posts?
Yes, I've loaned out my multimeter so waiting it to be returned. This behaviour has been happening for a long time. The high idle itself is only a recent phenomenon - I missed the part about 1200rpm being emergency mode.
Well make sure you read it carefully because having thought about this a bit more the problem does appear to stem from the throttle position sensor.

One other thing to check if you can borrow one is swap out the brown double relay by the ECU. It could be starting to fail perhaps. Unlikely from the codes but if you can borrow a known good one from somewhere, why wouldn't you try it?
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

Okay - do you know the pin numbers for the TPS?
I know that there will be +5V, Gnd, and the output - what is the 4th pin?
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

dave_xsara wrote:
26 Mar 2021, 15:25
Okay - do you know the pin numbers for the TPS?
I know that there will be +5V, Gnd, and the output - what is the 4th pin?
Yes. Pin 4 (Green wire) is earth via ECU Pin 22
Pin 3 Voltage (Green)
Pin 2 S2 (Signal?) (Pink)
Pin 1 S1 (Signal?) (Green)

Now assuming it's wired the same as a Xantia X2 then the following is true:-

Pin 3 TPS, Pin 3 Fuel Pressure Sensor and Pin 1 Intercooler Induction Pressure Sensor are all linked via Splice E113A which is located in the loom 20MOT which is somewhere between yellow connector IC60 (see photo) and the TPS. The splice consists of 4 green wires.

The switched earths for TPS, FPS and Induction Pressure are linked via Splice E141.
Location of IC60 which is the one that can be affected by clutch change.  Recommended repair is to detach each side and solder (source: Citroen)
Location of IC60 which is the one that can be affected by clutch change. Recommended repair is to detach each side and solder (source: Citroen)
Attachments
Location of induction air pressure sensor
Location of induction air pressure sensor
Location of Fuel Pressure Sensor on Xantia X2 (Under FPR - it's a fuel filter out job!)
Location of Fuel Pressure Sensor on Xantia X2 (Under FPR - it's a fuel filter out job!)
Approximate location of E141
Approximate location of E141
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

Rhothgar wrote:
26 Mar 2021, 17:40
dave_xsara wrote:
26 Mar 2021, 15:25
Okay - do you know the pin numbers for the TPS?
I know that there will be +5V, Gnd, and the output - what is the 4th pin?
Yes. Pin 4 (Green wire) is earth via ECU Pin 22
Pin 3 Voltage (Green)
Pin 2 S2 (Signal?) (Pink)
Pin 1 S1 (Signal?) (Green)

Now assuming it's wired the same as a Xantia X2 then the following is true:-

Pin 3 TPS, Pin 3 Fuel Pressure Sensor and Pin 1 Intercooler Induction Pressure Sensor are all linked via Splice E113A which is located in the loom 20MOT which is somewhere between yellow connector IC60 (see photo) and the TPS. The splice consists of 4 green wires.

The switched earths for TPS, FPS and Induction Pressure are linked via Splice E141.

For the induction pressure sensor fault to be registered, (P0234) Major Fault, you need a difference of 200mb at idle between the inlet pressure sensor and the atmospheric pressure sensor and you would receive "inlet pressure sensor coherence" message. Although you are not currently receiving such a fault, you will see 900mb for the atmospheric pressure in Lexia if it is not operational and this would also cause emergency mode. Interestingly, it is all part of the linked wiring.

It's a 3 pin connection. Ignition On. 4.8 - 5.15V betweeb Pins 1 and 2.

At 1 bar (1000mb) you should see 2.3V between Pins 2 and 3 on this component increasing as the pressure increases.

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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

Handily enough it was marked up on the sensor and block connector.
I've only managed to do the static tests.

With component connected:-
Pins 3 - 4 should show between 4.8 - 5.15V.
Correct: 5.01V
Pins 2 - 3 Linear variation of the voltage from the "throttle released" position to the throttle pedal full down" position: 0.28 - 1.6V. TBC


With connector disconnected:-
Pins 2 - 4 you should see infinite Ohms.
Correct
Pins 2 - 3 Ditto. Correct


I'll do the others later.
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

dave_xsara wrote:
26 Mar 2021, 18:31
Handily enough it was marked up on the sensor and block connector.
I've only managed to do the static tests.

With component connected:-
Pins 3 - 4 should show between 4.8 - 5.15V.
Correct: 5.01V
Pins 2 - 3 Linear variation of the voltage from the "throttle released" position to the throttle pedal full down" position: 0.28 - 1.6V. TBC


With connector disconnected:-
Pins 2 - 4 you should see infinite Ohms.
Correct
Pins 2 - 3 Ditto. Correct


I'll do the others later.
Remember you have an intermittent fault so you should, by rights, be working the wiring to see if the reading drops or do a load testing on the wire to confirm resistance under load.
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

Was a bit more of a hassle than I expected - I couldn't back probe the connections as they were sealed - so I had to push pins through the wires to get a connection. Glued them afterwards to protect them.

Pins 2 - 3 Linear variation of the voltage from the "throttle released" position to the throttle pedal full down" position: 0.28 - 1.6V
  • Idle: 0.22V
  • Full Throttle: 1.46V
  • Transitions up and down smoothly - even when wiggling the wires into the back of the connector.
Would a better test be to tap gently on the TPS in order to see if I can make the unit short?

Using Lexia the throttle position went between 0% and 83%. Should this not be 100%?
Also Lexia reported that Accelerator Hard Stop 2 was always pressed. What is this?


Need to use car tomorrow so will have to check other things over weekend.