Citroen XM Forum

MTXM wrote: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.

I wasn't aware of any after market bits on the car? There's the dump valve on the turbo as standard and then there's a boost controller mounted just under the scuttle - this was faulty when i started out and was replaced by a new one) but I didn't see any other dump valve?

By the way, one thing I didn't look at was the anti knock sensor (there might be TWO of these). The one at the front of the engine under the inlet manifold was looking cracked but no fault codes came up for it. It has a green plug under the manifold.

If you want Mark you can have the LED diagnostic reader I made. It's ideal for moving things along and any fault code can be cleared. Unless you just want to make your own - it's pretty simple.

The Idle stepper motor on the car is brand new but there's a second unit in the box of bits I brought that might be worth refitting for a test.

With all the bits off to change the sensor you could have removed the new crank sensor to check it was clean. I checked it and it had a bit of metal clinging to the end that no doubt caused iffy readings. But it's a pig to reach with the coilpack and such in place.

As I recall you showed a picture of an additional chip on the ecu circuit board Graeme and I removed the dump valve that was definitely not a standard item. Regards, Mathew T.

personally, I think it's time to take this car to a tuning specialist with a Rolling Road to get live data.

I suspect the mixture is lean and this becomes apparent when the engine is cold.

Dean wrote:..................... 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

Generally it does run fine, starts fine, when it cuts out starts straight up, definitely no misfire under load etc, just a slight stutter felt now and again, Graeme mentioned an occasional high idle in his thread but i've never experienced this, the slight idle fluctuation isn't all the time only when the motor first reaches operating temperature then idle is steady after driving a few miles.

My car definitely has the brown double relay (checked earlier) code on it is 240101, date stamped 92 so it's original, may be worth trying, will also see about getting the fuel pressure checked too.

Failing that may need to look for specialist help.

Looking through the net the cutting out/rough cold running does seem to be a problem with some 2.0 TCT cars, found a few cases of Xantia Activas with the problem too.

Just remembered a wee while ago to take a pic of the Amber lights, decided to peel off the film on the indicators as it looked a bit too much with the dipped beam lenses done.

Look's quite distinctive, as if an XM isn't distinctive enough as it is

You are going to be surprised at how much the film reduces light output.

Dieselman wrote:You are going to be surprised at how much the film reduces light output.

Probably, light nights are here anyway, can always take it off for the winter

That looks ace Mark.

It's true the yellow reduces visibility but it increases contrast so you can see obstacles, pedestrians etc easier on unlit back roads.

But you might want to remove the second inner lens of the lights to increase output

Here's how the CX looked with the selective yellow bulb caps

It really is a matter of basic physics...

Objects out on the road and pavements will come in all colours - red...yellow...green...blue...violet.
Blue is a pretty common clothing colour (denim, etc).

An object appears a certain colour only because it throws back (reflects) light of a particular wavelength. Other wavelengths (colours) are absorbed. A blue object appears blue ONLY if the light hitting it contains blue. Light a blue object in red, and it will reflect nothing: it will appear black/invisible.

White light is a mixture of Red, Green and Blue light - the primary colours. W=R+G+B.
Yellow light is what you get when you strip out the Blue (only the Red and Green get through). Y=R+G.
So, if you illuminate a blue object with yellow light, it will tend towards invisibilty.

Moral 1: If you want to see pedestrians wearing jeans, don't go for yellow lights.
Moral 2: If you want to see everything around, in best available detail, go for "full spectrum" lighting - i.e. White.

The only conceivable use for yellow lighting would be in thick fog, where light of shorter wavelengths (blue light) scatters more than long wavelength (red light), thus creating scatter and lighting haze. Red light punches through mist better than blue, which tends to scatter. That's why the daytime sky appears blue, and sunsets red.

If you must have yellow lighting, for safety's sake keep the tint pale (straw, not amber).
By using a coloured coating or film, remember that you are SUBTRACTING from your lighting, not adding to it!
Fashionable blue-tinted (5000K+) bulbs, and HID, come into this category, too, I'm afraid.