Fast idle...what is this?

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caeclyd
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Fast idle...what is this?

Post by caeclyd »

I am trying to find out how to reduce the speed of my fast idle. At the moment it is 1000 when hot. I have had a look at the haynes manual and it is as clear as mud.
There is some mention on this site of a cable from my thermostatic housing ? There isn't one.
It is a 98 Xantia estate 1.9td.
The only thing that seems to reduce the idle speed is this (image)
Image
It is not connected to the thermostat. On the pump side the cable is connected to a lever/cam . When I push the arm down the revs drop by about 100 rpm . Is this the fast idle adjustment?
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fastandfurryous
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Post by fastandfurryous »

This is a vacuum capsule. The wax capsule in the thermostat housing was discontinued at some point around 1996-7 ish, and the replacement system uses vacuum to control the hot/cold fast/slow idle. More than that, I don't know, as I've yet to work on one. It does sound like you may need o make some adjustment (possibly to the ferrule you have in the 'photo) as 1000rpm is too fast. Idle should be about 750-800rpm for non-AC or 800-850 with AC.
citronut
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Post by citronut »

if cable is to tight it will hold revs up,try loosening nut in you pic and screw adjuster in to left of your pic regards malcolm
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Post by RichG »

Caeclyd (is that your real name?),
On your model, like mine, the fast idle is controlled by a solenoid valve. The disc on the right hand side of your photo is a vacuum chamber. On the right hand side of the cam shaft is a vacuum pump (large alloy casing). From the bottom of this is a rubber pipe which goes to a tee pice. Each side of this tee goes to a solenoid valve mounted on the LHM tank support braket. The valves are similar however the connectors are different colours. The Blue one is the fst idle and the Green one is the EGR (Exhaust Gas Recirculation) valve. Check that all the pipes are in place and that they are not split at the ends. Any air leak will cause the fast idle not to work. The Fast Idle valve is prone to failure and is not cheap to replace.
If you take the valves off the car you can check their operation by applying 12v to the terminals and they should 'click'. Mine did this but then failed after about 5 minutes of being energised. The de-energised state is fast idle.
Hope this helps
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caeclyd
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Post by caeclyd »

"Caeclyd (is that your real name?),"
No it's Rory[:D]
Thanks for all the advice. I will return for another look in between showers !
citronut
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Post by citronut »

are there pipes coming of the unit in pic or or is ths just a rubber bufer on the cable,i would have thought if there was any vacum units in throtle system it would be the fly by wire throtle not cable opperated please correct me if im wrong regards malcolm
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Post by caeclyd »

Ok, I have had a play. Pipes are OK and I have adjusted the cable so it is slack. It made no difference to the hot idle speed.
What I have done is adjusted the fast idle on the Bosch injector unit. (this was the cam at the other end of the cable.) The rpm setting is now 950 still a bit high.
I guess i will have to remove the fast idle valve and give it a test.
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Post by RichG »

Rory,
If you find that the fast idle valve is kaput but the EGR valve is OK then it is possible to reverse their functions. The blue and green plugs are identical except for the lugs on the side. It is possible to shave the lugs in the sockets on the valves to enable the blue plug to fit the green valve and visa versa.
When I tested my new valves (I bought one of each) the resistance appeared to be identical, about 27 ohm, although the fast idle valve is more expensive than the EGR one (EGR £18.55 + vat, Fast Idle £29.15 + vat in Sept last year).
Disclaimer:
1) I cannot guarantee that the valves are the same and that you will not damage something if you wire them incorrectly.
2) This will disable the EGR system which may damage the environment.
Reagrds
Richard
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Post by Chrispy »

That's funny...my hot idle is also too high and this cable vacuum thingy also makes no difference. I've messed around with it something rotten....I'd be interested to see a fix on this!
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fastandfurryous
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Post by fastandfurryous »

In which case you now need to adjust the idle stops at the pump end of the cable. Is it a bosch or a Lucas pump? There are some adjusters for both the fast and the slow idle.
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Post by paranoid »

I have had to change the blue solenoid on both my xantia's 97 and 98 TD's
Solenoids connect to a bracket thats held on to the LHM tank, they pack up after a few years and the dealer usually has them in stock as it's common.
Only a 10 minute job to change (2 rivets to drill out and replace with screws)
Follow the tube from the pump it goes up to the bulkhead area by Lhm tank
Test by sticking a 12volt feed up it, It should click
(All this was learn't from the forum the first time it happened and its worked twice)
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davek-uk
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Post by davek-uk »

I was less generous. I have simply placed a pipe from the vacume pump direct to the fast idle diaphram. My engine is happy to start on slow idle throughout the year. Helped, I guess, by the slow idle being a bit too high.
How the hell do you get to the slow idle adjustment? It's way down the back of my Bosch pump...
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Post by Kowalski »

I had to replace a relay on my '97 too, but the dealer didn't have it in stock, in fact not one of the three Citroen dealers that I'd call local had one and it had to be ordered in specially. I didn't replace the rivets with screws, I bought a pop riveter which hasn't done a whole lot of riveting since....
I had a second fault with the vacuum system where the hose that goes to the EGR valve hardened and split at the end. I simply cut the hardened / split end off the hose and pushed it back onto where it came off, obviously there is a limit to the number of times you can get away with doing this because the hose will get too short...
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fastandfurryous
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Post by fastandfurryous »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by davek-uk</i>

I was less generous. I have simply placed a pipe from the vacume pump direct to the fast idle diaphram. My engine is happy to start on slow idle throughout the year. Helped, I guess, by the slow idle being a bit too high.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Almost every XUD engine I've ever had (and that's a lot... over 30) has been like this, as the early wax-capsule unit fails. Never seems to be a problem.
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">How the hell do you get to the slow idle adjustment? It's way down the back of my Bosch pump...<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
You employ a 12-year-old with very small hands to do it [:D] Or, as I did, take the intercooler off. You can happily run the engine at idle with the intercooler off, just don't rev it.
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