Idle speed too high

Chrispy · Post by **Chrispy** » 17 May 2005, 22:25

I've been searching through the archives on this but can;t seem to find a clear resolution for this...well, not one that makes sense anyway! My 99 TD Xantia idles at about 1000rpm all the time, hot and cold. Now with it being a late one with an armoured Bosch pump, I gather it has a different kind of idle control device to the old wax-stat one.
Now, there's a cable going from the back of the pump up to what looks like a vacuum device near the bulkhead. The cable for this is quite slack and makes no difference to the idle speed if it pull on it or not. My idle also does not vary with the air con on or off.
Is there a definitive fix for this? I'm almost tempted to adjust the screws on the back of the pump to force the idle down to the normal 850. Any ideas chaps?
Also, could they be in lamens terms please as I'm still learning when it comes to these things! [:D]
Cheers,
Chris.

zzf00l · Post by **zzf00l** » 17 May 2005, 23:01

Hmmm mine does exactly the same ..... 1.9td 1999

BrianM · Post by **BrianM** » 17 May 2005, 23:58

If you follow the pipe back from the vacuum unit you will see 2 solenoids riveted onto a unit that is in turn bolted onto the LHM tank stud. One is the fast idle the other is the EGR. I had the same problem on a 97 TD, the cable appears to be stretched, and the solenoids duff, (the solenoids can be tested with a 12V supply, you should hear them clicking, also check the air pipes from the vacuum pump and the solenoids), so adjusted the two screws on the back of the pump to bring down the idle. I think that with air con it may not be as simple for you though. I'm sure some of the others will clarify this.
Brian

derekjl57 · Post by **derekjl57** » 18 May 2005, 03:18

mine's the same - Xantia 97 TD.
I thought that it should normally idle at about 800, then if the AC is switched on, the solenoid pulls in, lets the vacuum in (or out?) which moves the cable to increase the idle speed to 1100. Only it doesn't. Idles at 1000 all the time....
Anders??? Help?

fastandfurryous · Post by **fastandfurryous** » 18 May 2005, 04:48

This is a fairly common problem.
I've had something like 30 XUD engines over the years, and hardly any of them have had working fast idle devices. (usually due to dead waxstats). The fast idle is supposed to work when the engine is cold, to bring the idle speed up a bit, countering the effects of cold oil etc. If you simply set the idle speed to about 800 RPM, the engine will cope just fine. The difference between cold idle and hot idle will be about 30-50 rpm, which is fairly insignificant.
Even the aircon being on doesn't make very much difference: My 405 1.9TD has a failed waxstat, so I've just disconnected it. The slowest it will idle is about 750 RPM which is when the engine is stone cold and the aircon on. The fastest it will idle is about 850, which is with a hot engine, aircon off. I can see the need for a fast idle device in ultra-cold weather, like sweeden, but in the UK's temperate climate, it's a bit un-necessary.

Post by **RichardW** » 18 May 2005, 12:53

I think the cold speed idle also slightly modifies the timing of the injection pump, so it should be working really. My 97 TD has a working wax stat type device, and air con. When the air con is switched on and the engin hot the idle dips to just below 800 rpm - and then it's noticeable that it needs a bit of throttle to get away, hence why Citroen probably upped the idle speed with A/C on on the later cars with the vacuum controlled devices. On the wax stat devices, the cable is taut when cold and slack when hot (or it should be!). The lever on the back of the pump moves to the right of the car for slow idle and to the left for fast idle. I imagine that the pump oepration will be the same on later cars. Try pushing the lever about to see if you can alter the idle speed. If it won't, then it's possible that someone has messed about with the screws to fix the idle speed. Note that there's not much movement - only 5mm or so - in the lever. If it's seized, or 'adjusted' then you need to get it working and reset the cold and fast idle speeds, then look at getting the vac solenoid working.

davek-uk · Post by **davek-uk** » 18 May 2005, 15:28

Do a search to get more info on this subject. It has been discussed before and at great depth.
Basically, a vacuum sucks the diaphragm on the pump activating the fast idle lever when the engine is up to temp and the aircon is off. It is common for the vacuum to fail (split pipe or failed solenoid) and if left for a long time the lever can jam with dirt etc. The vacuum pump supplies the vacuum and the fast idle solenoid controls how much vacuum gets to the diaphragm.
My engine is quite happy starting in normal idle (i.e. not fast idle) as it is set too high; as a result I have put a pipe direct from the vacuum pump to the diaphragm and cut out both solenoids.

Chrispy · Post by **Chrispy** » 23 May 2005, 00:27

Right, after having a bit of a play, there seems to be 2 things at fault. Firstly, the cable running from the vacuum actuator is waaay too slack. Even when fully adjusted out, it's still too slack to pull on the lever on the rear of the fuel pump. It would appear that the cable should only be slack when cold as when I manually pulled it, thus moving the lever over, the idle speed dropped to about 850rpm, then as soon as I let go it went straight back up to 1000. In which case that means that to have a low hot idle speed, the actuator vacuum jobby near the LHM tank must be on all the time, pulling the cable tight. It only let's go when cold or when needed such as under load i.e. Air con. This is a crazy design really and I'm not surprised it fails. Ideally the cable should be slack all the time when warm, only going tight when cold etc to increase the idle, not the other way around....typical French! They've got a few things to learn from their German neighbours.
Also, my vacuum unit isn't even pulling. It's in the outermost position when warm when in fact it should be in, pulling the cable tight and pulling on the lever, lowering the idle (that's also if the cable wasn't as slack as pi55).
So, as a fix, I screwed down the cold high idle screw so that the lever on the back was forced over to run on the hot setting all the time and wont move. Now, it'll sit at 850 all the time. Nice.
So now, unless i really find that I have to, I'm not going to replace the vacuum actuator/ relay, or the slack cable. We'll see how it goes.....

pete_wood_uk · Post by **pete_wood_uk** » 24 May 2005, 18:46

As a fellow-sufferer from this problem (who hasn't bothered to do anything about it), can I ask if the position of the lever on the back of the pump affects anything other than the idle speed? In other words, am I harming fuel consumption or anything else by ignoring the problem? (Other, obviously, than the trivial difference in fuel consumption between a 850rpm and a 950rpm idle)?
Thanks
Pete

Seamster15 · Post by **Seamster15** » 24 May 2005, 18:55

check this - http://www.andyspares.com/discussionfor ... Terms=idle

fastandfurryous · Post by **fastandfurryous** » 24 May 2005, 19:11

The lever on the back of a bosch injection pump alters idle speed only. It has no effect on timing.
The adjustment in timing is done by an alternate means. On early (very early) pumps there was another wax unit on the front of the pump. These fail too, and are again somewhat irrelevant. The later method works. It is a small bore pipe running to the bottom of the pump, where there is a pressure actuated mechanism (internally). I have been warned NEVER to drop an injection pump on this casing, as it will pinch the internal piston, and jam it, thus sticking it in the "engine off" position, and creating masses of smoke when running. This method works properly (and works off the fuel temperature).

richp · Post by **richp** » 29 May 2005, 17:34

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by BrianM

If you follow the pipe back from the vacuum unit you will see 2 solenoids riveted onto a unit that is in turn bolted onto the LHM tank stud. One is the fast idle the other is the EGR. I had the same problem on a 97 TD, the cable appears to be stretched, and the solenoids duff, (the solenoids can be tested with a 12V supply, you should hear them clicking, also check the air pipes from the vacuum pump and the solenoids), so adjusted the two screws on the back of the pump to bring down the idle. I think that with air con it may not be as simple for you though. I'm sure some of the others will clarify this.
Brian
<hr height="1" noshade id="quote"></blockquote id="quote">

richp · Post by **richp** » 29 May 2005, 17:41

i am also experiencing this problem i have messed about with the two
solnoids so often i cant remember what pipe goes where can any one help with a diagram of which pipe goes to which solenoid thankyou<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by BrianM

If you follow the pipe back from the vacuum unit you will see 2 solenoids riveted onto a unit that is in turn bolted onto the LHM tank stud. One is the fast idle the other is the EGR. I had the same problem on a 97 TD, the cable appears to be stretched, and the solenoids duff, (the solenoids can be tested with a 12V supply, you should hear them clicking, also check the air pipes from the vacuum pump and the solenoids), so adjusted the two screws on the back of the pump to bring down the idle. I think that with air con it may not be as simple for you though. I'm sure some of the others will clarify this.
Brian
<hr height="1" noshade id="quote"></blockquote id="quote">