Citroen XM Forum

I have been using LED bulbs in a number of different applications for a while now.
Not found anything that gives enough power to use as a headlamp or fog lamp bulb yet.
Have also found the two standard LED colours present problems in my trials.
I found both colours are far to white, even cool white had virtually no yellow tinge.
COB LED's are the most powerful currently available as these are manufactured directly onto a metal heat sink.
That gives the closest possible positioning of the LED devices.
That limitation means that multiple LED's cannot be point source with current technology unless lensing is used.
I have found in practice that the output from LED floodlights is about half that claimed.
So to replace a 110W halogen needed a 20W or 30W LED light, not the 10W recommended.
Still cutting power used by a factor of 4 is well worth it in most applications.

John

Got my new temp sensor fitted tonight

Access wasn't great, had to remove the Turbo intercooler pipe, coil pack (removed in the pic), and the slacken off the air filter to Turbo pipe, you can see the brown and blue sensors in this pic, green ECU sensor is underneath these, got it out with a 19mm socket and 1/2 drive ratchet, unplugged the blue and brown sensors to improve access and save damaging the plugs.



Thankfully the dealer supplied the right sensor and it screwed in fine.

Found the brown wire to the sensor a bit crusty with the insulation cracking off (age, heat from the Turbo)



Soldered in a new section of wire.



Heatshrink then insulated with some spiral binding.



It's all built back up now, hopefully this has cured the running issue, will find out in the morning when i take it for a drive

Felt like i was on a roll so stripped the headlights down to tint the dip beam lenses.



Decided to use the yellow paint on these as i thought the stick on film wouldn't cope with the heat, battery went flat in the camera so didn't get any more pics but it's turned out not bad, quite like the look. (will post daylight pics tomorrow)

Managed to ruin one of the headlight reflector front inserts trying to clean it



What i thought was dirt was sone of the silver coating worn off, i just made it far worse , have removed both for now till i decide what to do to restore them.

Well, just had it out for a short drive and it's exactly the same , so not the coolant temp sensor then

Just read a thread on the french car forum, an XM TCT with pretty much the same running problem, depressingly the guy has tried just about everything, even another ECU, suggestions pointed to the Double Injection Relay, anyone any experience of this ?, does anyone have a spare i could try ?, it's found under the piggyback ECU cover infront of the main ECU box.

Big brown thing marked Bitron 240109

It supplies power to the fuel pump, injectors and ECU so pretty crucial.

I am sure ive got one (big brown relay) but to be honest this wont be the issue, a relay is a switch as you know, it will either be on or off, usually the result of one failing is cutting out not rough running and jerky drive with cutting out on the over run.
Your symtoms are only when engine is cold is that correct? with engine stalling out on a trailing throttle or cutting out on reaplication of throttle?
If so it could be a fueling issue, i would think fuel pressure issue which is easy to check if you have a pressure gauge to cut in line with the fuel rail feed, the thing in line with the fuel feed is the damper, the one on the return is the pressure regulator. Make sure the vac/boost line from the throttle body to pressure regulator isnt leaking and let me know if you would like the di relay to try.

I have had a couple of 2.0i engines suffer with complete loss of power followed by stalling and inability to rev the engine (basically a coas to the side of the road popping and farting then cutting out with lots of cranking to attain a very weak start where the engine will run on two for a few seconds before bursting back into life, at first an ignition amp cured this but it turned out to be a bad yellow wire on the big engine to fuse box loom where the plugs are under the lhm tank, very common issue with the big square plugs.

D

D

Cheers Dean, you are probably right, the Relay would either be working or not.

Running problem is only when cold apart from a slight stumble now and again when hot, particularly when driving up a long incline, uneven idle when first heated up but that goes after driving for a while, fault is very much dependant on ambient temperature.

Vac line from pressure regulator is fine, may be worth checking fuel pressure but wouldn't there be more significant problems when the engine is hot ?, apart from the slight stumble the engine pulls fine, Turbo boosts up ok.

This is what the other guy posted on his thread, quite depressed when i seen this list (though Graeme has done pretty much all of this already), the poster below has fitted a new fuel pump and pressure regulator and checked the wiring under the LHM tank, the thread was back in 2012 with no conclusion.


[QUOTE]
Recently replaced:

Intake Air Temperature Sensor
Coolant Temperature Sensor
Oxygen Sensor (Lambda Sond)
Fuel Pump
Fuel Filter
Fuel Pressure Regulator
Coil
Sparkle plugs
Plug leads
Ignition module
TDC sensor
Anti Knock Sensor
Air Filter
TPS
Crankcase breather valve

This has been checked/done:

Idle stepper cleaned
Boost pressure control valve checked - OK
Evaporation valve to the charcoal filter tested - OK
Mass points in the engine compartment cleaned left and right and on the engine block.
All underbonnet connectors cleaned with contact cleaner, including the one underneath the hydraulic reservoir.
New fuse 30A
A different ECU showed no improvement, however, it was from a used vehicle.
A compression test of the engine in cold state yielded 11, 12, 10.5, 11 bar, in the warm state 11, 12, 8.5 11 bar.
So the second cylinder has a bit of a compression loss when warm.
Engine oil and coolant look good. No bubbles in the coolant, cylinder head gasket seems to be fine.
[QUOTE]

As the ecu seems to have been tinkered with I would replace that before doing anything else and another unit should be fairly easily obtained. There was also a dump valve fitted on the breather pipe against the bulkhead on the driver side when I bought the car. Regards, Matthew T.

Be very careful about the type of double injection relay.
There are a whole range of them with different pin combinations for different cars.
The 2.5TD for example uses a 240104.
As well as the number on the case there is usually the wiring diagram marked as well.
In addition to the two relays a number of car specific circuit links are included in the relay case.
One of my 2.5's came with the wrong double injection relay fitted.
This by fluke bypasses the keypad immobiliser so I have left well alone.

Check first on here which relay is fitted to similar XM's and compare that with yours.

John

I dont think the ECU is at fault here tbh, its worth a try but buying and replacing random parts isnt the solution, at a guess i would say the ecu mod has just altered ignition timing slightly and maybe deletion of the 12.5psi boost ceiling, maybe.
Low fuel pressure will give cutting out or stalling with sluggish restart or not and missing or hesistation on big throttle openings or high boost situations. Its worth just chucking a guage on the fuel rail, look for increase fuel pressure with snap wot and when disconnecting the vac line, probably be 10-15psi? about the same reduction in pressure on a trailing throttle or momentary dip in pressure when throttle snapped shut, whatever it does you shouldnt see any dip in fuel pressure when reving the engine.

I would be convinced that with rough running and missing under load its a weak mixture, a fueling issue in short, either because of a direct issue with fuel supply or mixture control.

D

Its a damn shame its not newer as you could get a lexia on it and compare graphs of fuel trim, O2 and maf which would point you in the right direction as if it was fuel you would be able to see it lean out on the O2 live data at WOT.

D

..................... Just read back through a bit, if its running fine but just cutting out, i would say something has an electricity leak, contact cleaner wont do a thing as its just solvent for grease and grime removal but it could be the double inj relay although i thought they were only fitted to keypad equiped cars. If the idle is high or fluctuating which i think it was with this car? its almost 100% a Vac leak somewhere.

Good Luck with it.

D