Ecu's And Relays

Only a hundred? ...........well you did say you had to trim your collection down a bit Andrew.........


The non starting 2.0 turbo..................

Start the car from cold, no problem. Drives ok and will go as far and as fast as I want, just like normal.
Turn the engine off. Restart it. It runs for a few seconds, then fades away.......almost like the fuel supply has stopped, and it's using up the fuel that's left in the pipes ...........but I'm no expert.
Keep turning the engine over but nothing happens.........it's dead (it turns over ok, no starter or battery problems).
Leave the car for a few hours to cool down completely. Now it starts ok, just like before.
Like I said, I'm really no expert but from what little experience I have I'd say its fuel starvation.......however, when I called the AA out to it, the man said there was no spark at the plugs and no power at the injectors. His diagnosis......."most likely the crank sensor"...............so I fitted a new one, it made no difference.

I spoke to a Citroen XM specialist in Blackburn......he suggested the fuel pump..........but that doesn't make sense, why would it run ok (even when hot) untill I turn the engine off, then refuse to start again, and I can hear the pump running when the ignition is turned on.

As the problem seems almost certainly heat related, I suspect a temperature sensor, but I can't find one.......niether can anyone else.
Also, the whole fuel and ignition system doesn't seem to follow any logical path.........everything seems to effect/control everything else.

I took the car to a local auto electrician, he had one of those hand held diagnostic gadgets that plugs in under the steering column, but he said the car wouldn't communicate with his equipment (well it is French).

The mechanics who have seen the car just scratch their heads and look baffled (I don't blame them, I feel the same, it's just a mass of pipes), it's not like a normal engine.

I've worked on fuel injection systems before, I used to be able to open a Vauxhall bonnet and identify all the fuel injection components at little more than a glance (airflow sensor, throttle valve switch, temperature sensor, etc) pretty straight forward, but this one........? There's nothing I recognise........just pipes.......and more pipes.............and there's no information available on this engine.....it's like it never existed, apparently Citroen only produced diesels and V6's.

After a bad experience with an Opel 'money pit' Senator CD a few years ago I vowed I'd never do it again.
Normally if I get a problem like this, I'll just get rid and find another car. I've been fairly patient with this one (it is a nice car......when it works).......but time (and my patience) is running out.

I didn't pay much for the car, and if I sell a few parts then weigh in what's left I can get back what I've spent on it (perhaps even make a small profit........a first for me).

So I'm reluctant to leave it sitting in the corner of a workshop waiting for the mechanic to decide whether he wants an arm or a leg (or both), with the possibility of having to give up additional limbs for any work that needs doing (there's always something) to get it through the MOT.
And they won't MOT it first because of the starting problem.
And of course, no MOT means no road tax, so the DVLA will be sending the boys round before long to take the situation out of my hands (and take some of my cash), so time is running out.

I had expected that I would eventually canibalise the 2.1td for the good of the 2.0 turbo (the petrol car is in much better condition than the diesel), but now it looks like they may both be donating their organs to other XM's.

Do you ever get those days when you wish you'd bought a Mondeo?.........or a Vectra?.........or a Focus?........or a Passat?........or anything that's not a Citroen................................

Paul.

ps.......I'm not the only one with this problem..............

http://club-xm.com/forum/index.php?showtopic=652

I contacted alan to see if he got the problem sorted.........his car has been sitting in his garage the last two years gathering dust................

I'm not expert (especially with electricks) but hope that chucking a few thoughts into the
mix from past experiences with Xm's may help you work around this problem.

The temperature sensors are on the back face of the head at the gearbox end just down
below the electronic distributor you've pictured with the knackered TORX head bolts.
There are 2 or 3 and it may well be the loom isn't very clever on the multi plugs to them
not the sensors themselves.

Initially I thought fuel issues would be the fuel pump from the tank and I've had problems
with these on Xm's and Xantiae and if I had one spare I'd plug it in to rule it out but as you
do state the spark is missing too it does point to a central source like the ECU isn't prepared
to energise the injectors or spark anything as there's no signal which in a roundabout way
does come back to the flywheel sensor. Are you ABSOLUTELY CERTAIN the sensor is a
known good working one or one off a scrapper in a yard; that may have been the reason
it was in the yard!!

I had a flywheel problem a few years back with a CX GTi Turbo that wouldn't start after an
engine out clutch fitted job. Turned out I'd somehow knocked a slug on the flywheel that is
the actual post the sensor reads when the engine turns so the ECU thought the engine was
standing still. Had to take the fully completed engine bay back apart all over again and the
engine back out!!

When all said and done, it points to a poor connection in the engine bay that's actually
breaking up when the engine gets' hot and we all know that Xm's are good on this score.

Whilst I'm supposed to be working and have just rattled this off quickly, one final thought
for now would be the supplementary air feed valve - the gizmo attached to the side of the
battery box - these have caused me real grief in the past on an 8v 2.0i as the single
needle jet gets' lazy with it's opening of the jet and I could gently tap it and the car will
run properly until the next start!

All the best,
Andrew

This post has been edited by Andmcit on July 18, 2008 09:44 am

Thanks for the suggestions Andrew.

The crank sensor was new from GSF, I've no way of checking it.

The little black rectangular thing bolted to the cyl. block, under the distributor was pointed out by someone else as a possible temp. sensor. I unbolted it but found that theres no connector, it appears to be an integral part of the wiring loom, I'd have to snip the wires to replace it. I haven't found any others, I'll have to have another look.

As for the fuel pump, there is a five pin connector on it, I've no idea what the five wires do, I only expected two wires, three at the most. But if the pump is faulty then the car will probably have to go anyway, I've been told a replacement is around £250.

Other possible sensors I've found are..........a barrel shaped thing behind the drivers side headlight, with two rubber tubes coming from it, and a small plastic thing with a two pin connector fixed under the scuttle with three black rubber tubes coming out of it (I know it's something to do with the engine because when I disconnected it with the engine running, the engine warning light came on, when reconnected the light went off).

BTW, the engine warning light stays on for a few seconds after the engine has started then goes off, it then comes on again after a few miles (or when the engine has warmed up).

I went out to start the car this morning and now it won't start at all, hot or cold.

It looks like my only option now is a mobile auto electrician (why didn't I think of that before).

Thanks again,

Paul.

Do you have homestart cover!? Now's your chance...

I'm sure I can find you a working SH fuel pump; it may need a wire resoldering for the fuel gauge!
An erratic pump could be the villain of the piece here...

The square block under the distributor is a suppressor to stop interference on the radio IIRC so not
something I'd worry about.

The temp sensors are well hidden buried down below everything about 2" in from the end of the
head; they are there but you need to look for them!

TTFN

Andrew

Andrew,

I don't have homestart, but they wouldn't come out to the same fault twice if I did.
Their view is that I should have got the fault fixed..........which I would do if I knew what it was.

The SH fuel pump might be very usefull, thanks, I'll see if I can find someone to look at this one first, I don't want to change it unless I'm sure it's faulty.

I should have guessed the temp sensors would be placed somewhere far down and out of sight, I wish I'd known when I changed the crank sensor.
If the sensors aren't too expensive it might be worth changing them anyway, I don't suppose it's possible to test them where they are.

Thanks again,

Paul.

Hi Paul.

Thinking this through, I believe the temp sensors would only really affect the efficiency of
the engine's running but not directly stop it running which appears to be your problem right
this moment. The energisation of the injectors and the sp[ark will be from the ECU so
you're bang on to get yourself one as an alternative to the original.

One more thing that springs to mind is the rather shaky start to my v6 24v's ownership
as it wouldn't start to drive off the trailer I'd just driven it on and towed a fair distance!
It sat for over a week not making any attempt to fire up with my panicking about
everything that was new and weird under the crammed bonnet.

I tried a lot of things including trying to read fault codes etc etc but finally nailed it to a
poor loom connection entering into the ECU box. I've subsequently disturbed it and had
the same scenario but careful systematic retightening of all connections with an immediate
try of the starter got it running again; I suspect a slight crimping on the main loom or
simple oxidation in a multiplug .

TTFN
Andrew

Hi Andrew,

Well I'm glad you told me that, I'll leave the temp sensors alone for now.

I'm keeping my fingers crossed that it is the ECU, but I'll be surprised if it is that simple.

Anyway, I'll be away for a few days, so hopefully, the ECU will have arrived by the time I get back, and I'll be able to give it a try.

Thanks again,

Paul.

The replacement ecu made no diference.
I have however discovered that the fuel pump isn't working now. perhaps there was an intermitent fault with it before.
The question now is how do I determine if it is a faulty pump or if the fault is elsewhere?
If I remove the pump, connect a power supply to it and it works, does that prove that it's ok and the fault lies elsewhere.
If so, what could cause the pump to stop working? Relay? Fuse? Sensor?
The Haynes manual electrical diagram shows the pump to have two electrical connections but mine has five, I don't want to start connecting live wires at random as I suspect the other connections are for the sender unit and I don't want to damage it.

Any suggestions appreciated,

Thanks,

Paul.

Paul

The BROWN double fuse as described earlyer in this post, thats on the front of the ECU boxes, IS the Fuel Pump controller and timer...

That could be the first suspect for lack of fuel pump being dead... did you get one with the bunch of ECU's and relays you just bought??

Rgds
paul

Thanks Paul,

Unfortunately that relay wasn't included.

Paul.

I think I may have a spare one for you to try!

PM your address and Ill get it off to you !

Paul

Well I finally got the car sorted (mainly thanks to Paul 'citroenxm' and Andrew 'Andmcit').................it turned out to be a knackered fuel pump.

The car went in for the MOT yesterday and after fitting a set of new windscreen wipers (oops, I forgot the check them), I was presented with a crisp new MOT certificate.

So now I can think about sorting out the little jobs that need doing.

First off, in my quest to better understand XM electrics, can anyone identify the relays on the main fusebox please.





Also, does anybody know which fuse or relay I need to replace to get the arm rest working again.

Thanks,

Paul.

Hi Minijet

Main fuse panel was varied during MK2 production so guide to relays really needs to be checked against model. You are going to have fun wiring that back in but taking it out makes the photo excellent.

A typical early Mk2 panel has the following:

1 - Relay 130 - Lights on audible warning
2 - Relay 170 - Flasher unit
3 - Relay 963 - Rear screen wiper timer
A - Spare
B - Relay 824 - Rear heated seats and/or sun roof relay
C - Spare
4 - Relay 820 - Heated rear screen relay
5 - Relay 848 - Engine running information relay
6 - Relay 962 - Windscreen wiper timer
7 - Relay 809 - Front windows relay
8 - Relay 874 - Sunroof supply relay
9 - Relay 806 - Front fog lights relay

In the list you will notice that the sun roof appears twice. This is not a mistake but the first rule of XM electrical fault finding. That is that every item has more than one supply, does not work if any supply is missing, upsets and crossfeeds other components so that you have little hope of clearing any faults without the right wiring diagram.

Regards

John

John.

That was going to be my next question.........which wire goes where? .......

Thanks,

Paul.

Hi Paul

For a bright spark like you I suggest you make all the connections multicoloured then sell the car quickly!

Regards

John