Hi All,
New to the forum but previous owner of 4 XM's.
I've just bought my first CX, a 1985 EFI Familiale.
It runs well but starts badly and idles roughly. Basically, although it's injected, at acts on start up like it needs choke, so I have to pump the pedal a bit and it takes about 15 secs or so to settle down.
Even then, when it's idling it falters a little, and the revs move up and down a bit. Tweaking the idle screw raises the revs but doesn't cure the fluctuation.
I've checked the big air intake concertina hose at the front for splits and can't find any. Does anybody know where I can find a photo of the other air hoses so I can check them for splits? I've also heard about a cold start valve at the back of the engine bay which may need looking at?
Any suggestions gratefully received.
Citroen CX rough idle
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citronut
- Posts: 10937
- Joined: 29 Apr 2005, 00:46
- x 94
Re: Citroen CX rough idle
its been qIute a while since i delved under the bonnet of a CX,
but the auxiliary air supply device should be a cylidrical unit with two rubber hose's,
were are you located
but the auxiliary air supply device should be a cylidrical unit with two rubber hose's,
were are you located
Regards, malcolm.
current ride a BX 1.7 TZD estate
1986 MK1 BX 1.9na D Auto(in Mothman Andy's stable )
layed up roppy 1.9TD XANT estate, now gone to meet her maker
purple and lilac metalic 2CV(VIOLET)registered to her in doors
1972 DS special been layed up aprox 31 years
current ride a BX 1.7 TZD estate
1986 MK1 BX 1.9na D Auto(in Mothman Andy's stable )
layed up roppy 1.9TD XANT estate, now gone to meet her maker
purple and lilac metalic 2CV(VIOLET)registered to her in doors
1972 DS special been layed up aprox 31 years
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Citroening
- Posts: 2511
- Joined: 26 Feb 2010, 20:19
- x 19
Re: Citroen CX rough idle
Welcome to CX ownership! Any chance of some pics please...! 
Is the main intake plenum plastic?
A small pinprick hole in this can cause idling problems whereby the plenum collapses - a modification is to replace the plastic plenum with a metal one.
We had similar characterisitcs from a CX 25 Pallas IE Auto (same engine) and a replacement plenum fixed it and normal starting/running was resumed.
What exactly would you like pictures of? I'm struggling to dig some out of the 2.5 non-turbo engine at the moment as most I have got are of the Turbo'd cars...
Is the main intake plenum plastic?
A small pinprick hole in this can cause idling problems whereby the plenum collapses - a modification is to replace the plastic plenum with a metal one.
We had similar characterisitcs from a CX 25 Pallas IE Auto (same engine) and a replacement plenum fixed it and normal starting/running was resumed.
What exactly would you like pictures of? I'm struggling to dig some out of the 2.5 non-turbo engine at the moment as most I have got are of the Turbo'd cars...
Franklin
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anucat
- Posts: 20
- Joined: 10 Sep 2013, 11:18
Re: Citroen CX rough idle
Thanks for your responses, guys.
By plenum do you mean the short fat concertina hose that sits behind the front offside headlight? if so it's black plastic. I've tried wiggling it while the engine's running but it made no difference. The next step is to remove it and examine it I guess.
The more I think about it I'm not sure the cold start valve is to blame as once the engine has heated up it would have no role would it? Why would a cold start valve affect idle at running temperature?
No photos as yet but will take some, in particular the engine bay. I think I need some help identifying the hoses I need to check.
I'm in South London, by the way.
Matt
By plenum do you mean the short fat concertina hose that sits behind the front offside headlight? if so it's black plastic. I've tried wiggling it while the engine's running but it made no difference. The next step is to remove it and examine it I guess.
The more I think about it I'm not sure the cold start valve is to blame as once the engine has heated up it would have no role would it? Why would a cold start valve affect idle at running temperature?
No photos as yet but will take some, in particular the engine bay. I think I need some help identifying the hoses I need to check.
I'm in South London, by the way.
Matt
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Citroening
- Posts: 2511
- Joined: 26 Feb 2010, 20:19
- x 19
Re: Citroen CX rough idle
Not a problem, Matt.
Here's a picture of that 1985 CX 25 Pallas IE under the bonnet - not an ideal shot but that's what I've found at the moment...
As you can see the main intake pipe has indeed got the concertina pipe which can sometimes split.
The larger plastic item to the right (plenum) can sometimes collapse and cause idling issues.
Does yours look "full" like the one above? Sometimes they can completely collapse in.
If you can post pictures then we can see if there's anything immediately obvious that could be causing an issue...
Here's a picture of that 1985 CX 25 Pallas IE under the bonnet - not an ideal shot but that's what I've found at the moment...
As you can see the main intake pipe has indeed got the concertina pipe which can sometimes split.
The larger plastic item to the right (plenum) can sometimes collapse and cause idling issues.
Does yours look "full" like the one above? Sometimes they can completely collapse in.
If you can post pictures then we can see if there's anything immediately obvious that could be causing an issue...
Franklin
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anucat
- Posts: 20
- Joined: 10 Sep 2013, 11:18
Re: Citroen CX rough idle
Brilliant, thanks so much. I shall check the plenum and take some pix this weekend.
Apart from the idling/start issue the car's a cracker. Waxoyled everywhere, only a little bit of rust, ride smooth (though the back kicks up a little over speed bumps). The seller told me it used to belong to a funeral director in Scotland (used for ferrying mourners not coffins!)
Apart from the idling/start issue the car's a cracker. Waxoyled everywhere, only a little bit of rust, ride smooth (though the back kicks up a little over speed bumps). The seller told me it used to belong to a funeral director in Scotland (used for ferrying mourners not coffins!)
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anucat
- Posts: 20
- Joined: 10 Sep 2013, 11:18
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anucat
- Posts: 20
- Joined: 10 Sep 2013, 11:18
Re: Citroen CX rough idle
As you can see, plenum is fine. Other air hoses seem ok but I haven't removed them to check.
Car started this morning without me pumping the gas pedal but it faltered quite a bit for the first 30 secs and the revs still waver a bit. I wonder if its dirty injectors as it was SORN'd for a year before I bought it.
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Car started this morning without me pumping the gas pedal but it faltered quite a bit for the first 30 secs and the revs still waver a bit. I wonder if its dirty injectors as it was SORN'd for a year before I bought it.
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addo
- Sara Watson's Stalker
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Citroening
- Posts: 2511
- Joined: 26 Feb 2010, 20:19
- x 19
Re: Citroen CX rough idle
Indeed that plenum looks a-ok. More pics of the rest of the car are welcome...
Neil with CGAT might have some ideas, so hopefully he'll see this thread...
Re injectors, I've heard of people getting them ultrasonically cleaned and they've been very pleased with the results...
Neil with CGAT might have some ideas, so hopefully he'll see this thread...
Re injectors, I've heard of people getting them ultrasonically cleaned and they've been very pleased with the results...
Franklin
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anucat
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Cyprian
- (Donor 2021)
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Re: Citroen CX rough idle
Nice looking car. Best of luck with it.
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Diabolical
- Posts: 243
- Joined: 27 Feb 2009, 20:08
Re: Citroen CX rough idle
I have a CX25 TRi and has always been like that I have tried just about everything and not cured it, incidentally year ago I bought a 25 Prestige same engine gearbox exactly the same with starting OK after 20 secs so I don't bother about it now.
However if you do find a cure would love to know.
David
However if you do find a cure would love to know.
David
06 C5 2.0L HDi Exclusive Estate 20020k and rising. 
1987 Citroen CX Prestige. De Corps Brun Maya - cuir blond tabac, très chic
08 Jaguar X-Type 3.0V6 Sovereign Estate - Green (HGZ) - Leather Ivory seats.
citroencx.co.uk
1987 Citroen CX Prestige. De Corps Brun Maya - cuir blond tabac, très chic
08 Jaguar X-Type 3.0V6 Sovereign Estate - Green (HGZ) - Leather Ivory seats.
citroencx.co.uk
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CGATCX25GTITURBO
- Posts: 292
- Joined: 21 Nov 2010, 10:58
- x 15
Re: Citroen CX rough idle
How do the plugs look?
leads and coils
valve clearances
temp sensor on back of head (near the idle screw)
has someone played with the the butterfly stop on the throttle body?
head gasket blowing between cylinders
leads and coils
valve clearances
temp sensor on back of head (near the idle screw)
has someone played with the the butterfly stop on the throttle body?
head gasket blowing between cylinders
Neil aka CGAT
1986 CX25 GTI TURBO 1 SERIES 2 'CGAT'
1998 XANTIA 19TD ESTATE
1987 BX19 GTI 8V
2012 Citroen DS3
1997 600 Bandit
2000 ZX12R from new
1989 CX GTI Turbo 62k miles in a barn since 2001, project started 2023.
1986 CX25 GTI TURBO 1 SERIES 2 'CGAT'
1998 XANTIA 19TD ESTATE
1987 BX19 GTI 8V
2012 Citroen DS3
1997 600 Bandit
2000 ZX12R from new
1989 CX GTI Turbo 62k miles in a barn since 2001, project started 2023.
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anucat
- Posts: 20
- Joined: 10 Sep 2013, 11:18
Re: Citroen CX rough idle
Looks like it could be any number of things then. Reckon I'll live with it.
Interesting it seems to be a feature of (at least 3) 2.5l injected (non-turbo?) cx's
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Interesting it seems to be a feature of (at least 3) 2.5l injected (non-turbo?) cx's
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