Citroen XM Forum

Bad spray pattern will give an incomplete burn which will send elevated levels of oxygen and Hc into exhaust, the O2 sensor will think its running rich and try to lean off, this usually gives rough idle and stutter on throttle application but yours does sound like intermittent idle control issues, poss your chipped ECU messing with the base ignition timing? Or the ECU's ability to throw a codefor out of tolerance mixture.

I see about the LEDs, is there a separate feed for switch illumination you could splice the resistor into? Rather than trying to squeeze it I to the switch itself.....

D

That's interesting Dean - if this car wasn't so good as munching money I'd just replace the injectors but it'll have to wait for a while. The existing set are no doubt the original factory set.

I'd really like to try a standard chip in the ECU as well (now that you remind me!)

No, the illumination for the switches is taken from a sort of 'common' feed and earth inside the switch. It's easy to adapt to on the standard switches but the one-touch switch is difficult as the original bulbs are hard wored to the switch. The reason there's a resistor in that location on the switch is that there's no room for it in the switch itself but there is a handy little gap along the edge above the terminals. The other good thing is that when the terminals are connected to the plug there's a good 1-2mm gap that allows the resister to be soldered onto the 12v feed terminal. I then just branched the connection on the other side of the resister to each eld of the switch with the +ve pin of each LED on the same side (there's a handy gap for the pins to poke through). The -ve pin of each LED I soldered it onto one little thin wire that I left after cutting off the old bulb.

I'll see about getting a few pictures up at some point.

All you need is for someone to send you an ecu
The injectors just need a good soak in something good for your health, like accetone , I fed mine with a tube of carb cleaner whilst flicking them with 6v, the filters were clean and in tact so never bothered with a service kit, there isn't much you can service anyway. 30 minutes to clean out all 4 including removal and re.........

D

Dean . . . Why a resistor is needed with an LED . . .

An LED is a diode (light emitting diode): it conducts current in one direction only, and emits light as it does so.
If wired the wrong way round, it will not light at all (no conduction).
If wired the right way round, and because its resistance in this direction is almost zero, it tries to carry a huge current from the supply - usually enough to blow it.

For correct operation, LEDs must be wired correct polarity (so they will light) and have the current running through them LIMITED to a safe level.
All LEDs have a specified FORWARD CURRENT, typically 20mA, but may be anywhere between 10 and 40mA.

To work out the correct series (current limiting) resistance for an LED, you simply apply Ohm's Law:
eg a 12v supply, to operate a 20mA LED:
R = V / I
R = 12 / 0.020
R = 600 ohms

A small chain of LEDs (up to 5 or 6 in practice) can be wired together, in series, and use the same current-limiting resistor as one.

Think of an LED as a piece of copper wire (or a fuse) that will only conduct current in one direction (but lights as it does so).
That's why the current must be limited by a resistor, to the safe working figure. [You wouldn't connect a piece of wire (or fuse) straight across a battery, would you?]

Most LEDs will operate from 2v and upwards (always with appropriate resistor).
LEDs are also manufactured to operate direct from voltages such as 5v and 12v. For these, the resistor is built into the item, so no need for an external one.

LEDs can operate from AC supplies (again, with limiting resistor). They just don't conduct when the current is momentarily reversed.

LEDs can be dimmed, simply by reducing the voltage supplied to them, or by increasing the series resistance. PWM dimming is also possible (don't ask).

Hope makes sense.

^what chris said!^

I could do with an ECU even if it's just to borrow to test and eliminate the chip as it is.

Let me know the ECU version number and I will send one out next week then, I can't remember what needs codes and what doesn't but if you need a code and its not 1111 etc you are welcome to canabalise it.

And thanks Chris that makes perfect sense, thanks!

D

Graeme, have you checked the injector O rings are sound. They compress with age and leak air into the manifold, causing a lean mixture.

Graeme has no keypad on the car Dean. With regards, Matthew T.

That's what worries my Matthew, all mine were keypad ECU's

D

Graeme, I followed a Dutch led conversion which Jaap sent me a link too. So really it was Jaaps fault I got in to LEDs!! Anyway, I put two bulbs in the one touch. You can wedge the bulbs into the contacts and they sit within the button right under the spots. Trouble is I ran out of white bulbs when I did the conversion and used 12v green bulbs from maplins. Which are like the headlights. Glow worms in jars.
So your way is very interesting. I have a spare one touch so I might experiment..... It's the one set of buttons that I didn't quite get right.