Xantia cold start mystery.......

paranoid · Post by **paranoid** » 09 May 2004, 15:21

Can one please explain what should be happening with the cold start on my td xantia please,
How do I know when the c/start cable is U/s, Tickover stays the same all the time hot or cold (1000 rpm), But with the engine hot and I adjust the cable near to the diaphram thing! the tickover lowers (850 rpm) till it started again then goes up 1000 revs again , with the cable dissconnected there is very little resistance at the diaphram just a puffing noise like theres a hole somewhere.
The lever at the pump seems to be at the stop all the time apart from when I adjust at the screw and locknut at the other end of the cable.
Please help someone i'm confused......[:)]

Dave Burns · Post by **Dave Burns** » 09 May 2004, 16:37

Check the electrovalve (blue one) for operation by shoving 12 volts up it and blowing through it, nothing should get through with no voltage applied and it should be open when voltage is present.
If thats ok, check the rubber pipework for cracks and the like, especialy the pipes going to the EGR valve and is electrovalve (green one), a leak in any of these pipes will cause both vacuum circuits to fail.
The cable needs to be pulled by the vacuum diaphragm to lower the idle speed (so adjust the cable while vacuum is applied), this will happen during idleing when the engine has reached a certain temperature.
When the engine is revved the valve should close and the diaphragm will release its pull on the cable, this will also happen when the aircon is switched on during idleing.
Not that the electrovalves when off are closed to the supply vacuum side, but the supplied side opens to atmosphere to vent the vacuum, so don't get the pipes the wrong way round.
Dave

paranoid · Post by **paranoid** » 09 May 2004, 17:01

Nothing happens at the diaphram ever, when its revved, Hot or cold, just when I move the cable by hand, there is a little puff of air coming out from somewhere on the diaphram (rocker cover side) but something must be happening somewhere because the revs go back up to 1000 revs next time its started and stay there, even more confused !!
I thought changing the cable would fix it.....looks complicated now DOH

paranoid · Post by **paranoid** » 09 May 2004, 17:20

The plot thickens............
I have just delved deeper into the problem, there is a pipe from the top of the blue valve that is just hanging loose behind the engine, the end is cracked and it looks like it was once connected to something, any idea where it goes ?

paranoid · Post by **paranoid** » 09 May 2004, 22:13

Just put pipe straight to diaphram on end of cable, tickover came down correctly, so i presume its the blue valve, any ideas how much etc, no leaks as far as I could see.

Dave Burns · Post by **Dave Burns** » 09 May 2004, 23:25

Pipe from vacuum pump goes to a tee piece which splits the supply for the two electrovalve, and from there on to their respective diaphragms.
New valves are a gnats under £30 so you want to be sure its at fault.
They are not easily found in breakers yards either.
Dave

paranoid · Post by **paranoid** » 09 May 2004, 23:46

Is it ok to run with the pump pipe on the diaphram like I did this afternoon? I'm crap at electrics how do I make sure which ones gone, before the revs didn't change when I switched on the air con, so could that valve be the problem. theres definately no leaks anywhere now.

Dave Burns · Post by **Dave Burns** » 10 May 2004, 00:05

Yes its ok to run like that, the EGR wont work unless it can also be piped up to its valve, but that being off wont harm anything, just don't pipe the EGR up to be permenantly open like you have done with the idle though.
Take a pipe from the tee direct to the idle diaphragm and the other tee end to the EGR electrovalve, or just go direct from the pump to the idle diaphragm and ignore the EGR for now.
Get two pieces of wire (you may need an assistant) go from the battery with both wires and touch the spades on the valve, either way round it will work the same, if its good you will hear it click, if not you will hear nothing, be careful not to short the two wires together or to touch any part of the car with the positive wire.
If you have a meter the coil resistance is about 370 ohms if I remember correctly, so a much higher value means its shot.
Dave

paranoid · Post by **paranoid** » 10 May 2004, 00:15

Cheers dave.......Will test when I get a day off work, does the lever on the pump affect fuel consumption at all, because it hasn't been brilliant since I bought the car, (still a lot better than my last car though) I was just a bit worried about having it suck constantly.

paranoid · Post by **paranoid** » 12 May 2004, 00:29

just tested them, blue one definately gone, There are no pipes going into the bottom of the valves, this is right isn't it?

Kowalski · Post by **Kowalski** » 13 May 2004, 14:18

There should be no pipes into the bottom of the valves, since the valves need to be able to vent the vacuum to atmosphere.

paranoid · Post by **paranoid** » 13 May 2004, 19:57

Thanks, just got valve from peugeot dealer, took some finding but got there in the end[:D]

paranoid · Post by **paranoid** » 14 May 2004, 20:04

Everything working correct now, thanks people!!!
One other thing does anyone know what the lever on the pump adjusts because it seems to drive very slightly different now? not in a bad way just different?? would it affect timing or fuel that much.[^]

Dave Burns · Post by **Dave Burns** » 14 May 2004, 23:10

The lever advances the injection timing by about 2.5 degrees measured at the camshaft.
Dave