Xsara II 2.0 HDI 90 limp mode

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Rhothgar
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

It’s an interesting point about whether the position should reach 100%.

I suppose it should be the latency and resolution in Lexia probably doesn’t allow this. I can check mine at some point and see if it does.

Personally, having access to an oscilloscope makes life much easier as I can capture things a DMM even fails to catch

A careful inspection of the TPS, as if any component, is necessary to see if it throws up any clues.

I don’t know if it can be stripped for instance.

As my father always used to say, “If it ain't broke, don’t fix it!”

If you’ve not already gone out. I would erase your faults, re-read, see what appears and re-erase. Read when you return too.
Last edited by Rhothgar on 18 Jun 2021, 11:24, edited 1 time in total.
dave_xsara
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

Got a reprieve, so car hasn't been out. I'll reset and go again. Problem is it has only happened on a very few occasions - I think all but one time I've posted on here.
Rhothgar
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

Yes I get that.

Thinking about it, it appears to only have happened when you’ve been on a motorway ie your throttle position has been near to its full potential.

It might be an idea to think about rigging up a temporary digital display in the car wired to the relevant pins on the TPS so you can see live data whilst driving. You’d only need to glimpse at it when the issue occurs to see what approx. voltage is at the time the issue occurs.

I wonder if there is some kind of OBD device which can record what’s happening.

I know we have some cheapo ones in stock but not sure what information they give. It depends on the app you link it to. Look up ELM327.

I’d bet there is an app out there that will allow you to customise visible parameters.

You’d maybe want throttle position, voltage of and speed of vehicle.

Lexia will take snapshots but it would mean to having it running then press relevant key when issue occurs to get a snapshot
dave_xsara
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

Got the call to help out in the end. What fault code would this trigger:
:roll:
IMG_20210327_172250.jpg
dave_xsara
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

Would that elm327 work with the citroen data? To run lexia I'd need to have the laptop permanently wired in which would be a hassle?
Rhothgar
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

dave_xsara wrote:
27 Mar 2021, 19:26
Would that elm327 work with the citroen data? To run lexia I'd need to have the laptop permanently wired in which would be a hassle?
Yes. An ELM327 model works with OBD I believe and certainly OBDII.

The crux of using that is finding an app which can give you the information you need to focus on with a suitably configurable screen so you can only see the few parameters you need on your phone screen to reduce the risk of anything untoward happening when you have to glimpse at the data when the fault happens. Perhaps you already have a phone bracket that you have positioned near to your line of vision in the car.

I am, of course, assuming you have a smart phone.

To rig up your Lexia isn't too difficult though I suppose you would need a 12V - 240V converter, your laptop and your Lexia interface.

You could take the fuse box door off so that's not in your way when you get in and out of the car leaving the Lexia diagnostic tool plugged in. Tape the wire to the u/s of dash under the steering so it is above your legs and then drape it over to the passenger side seat where you can keep your laptop whilst going on the run.

If you wanted to rig up a simple DMM display, you would need a cheap LED voltage display and something like this on your wires:-

https://www.ebay.co.uk/itm/2x-Safety-Te ... SwKVBgO0IU

and some banana plugs and wires coming back into the cabin to connect to the LED Voltage Display.

It's a bit Heath Robinson but could be the way to easily understand what happens to the voltage when things go awry.

To rule out your wiring, you need to load test all the relevant components really with a bulb preferably with the ECU disconnected and test between ECU plug and component to ensure wiring does not have high resistance. Checking continuity is hit and miss because the wire could be oxidised internally and you'll hit one copper core which is OK and get a good reading. Continuity does not necessarily prove a wire is good under load.

I am by no means an expert. Far from it. I taught myself diagnostics last year when the Xantia wouldn't start and it was a roller coaster of a ride.

Once you rule out your wiring (because it is so poor on Citroen) you can then focus on the components but I, in the end, resorted to borrowing a very expensive Picotech oscilloscope from my business which I have not yet returned. It's a great piece of kit but learning to understand what you are looking for is an investment in time.

Here was my living nightmare:-

viewtopic.php?t=64586&start=30

Got it started eventually then it died again 6 months later, then I had the fuel pressure regulator problems. I even got to checking for issues with the transponder because I kept going further and further down the rabbit hole.

There are some great pearls of wisdom in this post by Wheeler, Givemeabreak, RichardW and others:-

Here:-
viewtopic.php?t=66117&start=14

and here:-
viewtopic.php?t=66117&start=22

and no doubt in other posts on that thread.

This forum has a lot of experienced and helpful people but advice can only take you so far. It is almost impossible to diagnose something remotely unless it is one of the many common issues.

Anyway, got that resolved only for it to go back to it and find it had died 4 weeks ago (been standing since the last episode as I daren't drive it) when I was about to get it on the road for its MOT. All resolved now.

One other thing worth doing which will need doing at some point possibly if you don't lose the will to live with it is possibly the fusebox solder joints. It doesn't happen to every vehicle but it's worth knowing about:-

I have xantia_v6 to thank for this. When I got into the car and it wouldn't start again I truly was at my lowest ebb with it.

viewtopic.php?t=67714

The takeaway from all these ramblings is a loadtester is a worthwhile investment. I've still not got one. Cheapest is like £50 but you really need to understand how to test with them else you risk potentially blowing up your ECU. Wheelers suggests a 12V 21W bulb in one of the threads above.

I made up a fly lead using an old Dyson vacuum lead. I can get all around the perimeter of the car with it and apply 12V from the battery wherever I like (after careful consideration).
dave_xsara
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

Thanks - I'll take a look through this in more detail.

Can I ask how you got the factory diagnosis manual? Doesn't seem much point in me having the Lexia without a way of debugging the faults.


Just read through your threads there - seems that you had a lot more problems than me with your car! Excellent diagnostic work.

I have just bought the cable probes - they seem so much better than piercing the cable with a pin and connecting on. Useful addition to the kit.

Next task now is to see how much damage the trailer has done to the rear of the car and remove the hitch setup and tidy it up. #-o
Rhothgar
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

dave_xsara wrote:
28 Mar 2021, 12:11
Thanks - I'll take a look through this in more detail.

Can I ask how you got the factory diagnosis manual? Doesn't seem much point in me having the Lexia without a way of debugging the faults.


Just read through your threads there - seems that you had a lot more problems than me with your car! Excellent diagnostic work.

I have just bought the cable probes - they seem so much better than piercing the cable with a pin and connecting on. Useful addition to the kit.

Next task now is to see how much damage the trailer has done to the rear of the car and remove the hitch setup and tidy it up. #-o
I bought a comprehensive set of factory manuals for Xantia X1 and X2 manuals.

If you look at the first thread you will see the diagrams for the injection - starting side of things. Marc kindly posted those because I am a donor although I do have those manuals.

It may be worth asking the question of Marc (givemeabreak) to see if he has relevant manuals for your car but I am pretty sure it will be almost identical in this regard. If he has though, it's definitely worth becoming a donor as it helps with site maintenance and all the associated costs.

Be interested to know which cable probes you purchased?

Good luck with the tow bar
Rhothgar
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

This is what you want.

Shame they are in German and a bit pricey but if you intend for the love affair with your vehicle to continue, I'd suggest keeping an eye open for a set like this.

Still might not be complete but you have to work that out for yourself whether they have everything you need or at least the most important bits.

They usually included RP no.s for the individual manuals to suit your vehicle.

https://www.ebay.co.uk/itm/Workshop-Man ... SwTWRf~HcI

Having said that, why not contact them and see if they will split out the wiring diagram manuals that cover your year. You never know, you might get lucky or just offering £30 or whatever it's worth to you for the 2 manuals. In those complete 1, 2, 3 Wiring Folders will probably be the 2 volumes you need. They're diagrams so not much needs translating. The various diagnostics manuals for the vehicle will be in the folders with the ECU connector icon on 5th from left.
dave_xsara
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

Car has been behaving it self again until the weekend when it went into limp mode again.
P0191 is the main one now.
It happened when car was accelerating out of a corner. Wondering if fuel sloshing in the tank again the pump would cause a faulty pump to intermittedly fail again.
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dave_xsara
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

Spoke with a friend who said this is likely to be the in-tank fuel pump.
So I done some checks on it last night using the live data on the Lexia. measure pressure and reference pressure never settled at 0 as per the guidance. Flicks between -2, 2 & 6 bar.

Measured fuel pressure is 298bar (range 290 - 310).
Difference between measured fuel pressure and reference fuel pressure flickers between -2 bar, 2 bar and 6 bar, with an odd reading of -6 bar. (At steady speed, this value should fall to zero).
Engine speed is steady 803prm.

So there is something causing a problem with the fuel pressure measurement. -2 / +2 does sounds like that the LP pump in the tank is having an effect?
Rhothgar
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

Worth checking BUT... and I'm no expert, if you have a problem with the in-tank pump, it would be unlikely to start.

The fuel pressure regulator is preset to an Open Cycle Ratio of 95% on ignition switch on until the fuel pressure sensor reaches the 300 bar and then it switches off. Once the engine starts, the regulator runs at generally around 17-18% OCR at idle to keep the pressure within limits.

I need to look at some of the videos I have taken but I don't think I would concerned by the differential pressure as it must be within limits when the engine is running correctly.

Interesting to note that it drops to 13.7% OCR at 2088rpm on yours though, I'd have thought it would open more because of the greater fuel demand.
Rhothgar
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

Mine idles at 835rpm with 16% OCR. On revving, the OCR increases, as I suspected, as the revs increase.

Your FPR current is low too. Why?

Here is a link to my OneDrive video taken once I had resolved the issue (which had previously involved swapping the low pressure pump out only to find that didn't resolve the issue).

https://1drv.ms/u/s!Ar8AkvzZJWl9zzVbdmnivCT-TK17
dave_xsara
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Re: Xsara II 2.0 HDI 90 limp mode

Post by dave_xsara »

I thought the OCR was okay between 12 & 18% from the Lexia help info.

Anyhow here are some shots of the live data:
Redmi 6061.jpg
Redmi 6062.jpg
Redmi 6063.jpg
Redmi 6064.jpg
Rhothgar
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Re: Xsara II 2.0 HDI 90 limp mode

Post by Rhothgar »

I’ve never seen mine drop below 16% at idle and my video shows it increasing when revved.

Yours drops so it cannot have been getting enough fuel when it failed. Does it hesitate around 2000rpm intermittently?