C5 2.0 136 Turbo Issues ?

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With several hundred miles under the belt now, it seems pretty clear to me that the facelift C5 2.0 136 I have recently acquired likely has a turbo issue. Acceleration from low rpm is definitely producing smoke. Having got the Lexia working, I have read the turbo pressure and at low rpm actually got a value less than the recorded atmospheric pressure, rising above it as revs increased. I have looked, but not found any test figures for the turbo ----- does anyone have the figures for a known healthy turbo, please ?. Do the vanes stick ? If so, can they be unstuck ? Similarly, does the actuating solenoid give trouble ? I don't have any fault code to indicate the solenoid is defective, but wondered if perhaps it may gradually cease to operate correctly over its entire physical travel ? I am really in the dark with this, so any thoughts or data will be really helpful.

Thanks, Mike.

PS. Done some digging and came across this ---- http://uk-mkivs.net/topic/34834-vnt-tdi ... -problems/" onclick="window.open(this.href);return false;

I know it's the wrong make of car, but as a good guide to potential issues, thought it was really well laid out.

[h2ocooler]

Check the vacuum that controls the turbo, very common problem is the diaphragm for the swirl valves fails and then there is not enough vacuum for the turbo so it will over pressurise.
Find the swirl valve (not sure where it is on yours) and see if it moves when the engine is started and revved, if not blank the vac pipe to it and see how it runs.

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Check the vacuum that controls the turbo, very common problem is the diaphragm for the swirl valves fails and then there is not enough vacuum for the turbo so it will over pressurise.
Find the swirl valve (not sure where it is on yours) and see if it moves when the engine is started and revved, if not blank the vac pipe to it and see how it runs.

Thanks for the info. I presume when you refer to the swirl valves, you mean the variable bits in the turbo and the actuator bolted to it ?

I have found the repair section for the turbo in the Citroen manual and removal for repair looks to be serious bad news, including subframe removal. Anyone found yet whether there are any worthwhile shortcuts ? Is it feasible to change the actuator in situ ? I have felt the actuating rod for the variable vanes and it does move, although fairly stiffly. I put this down to the possibility that the actuator is sprung ?

I also fail to see why over pressure would produce smoke at low rpm ? What I would really like to find are the figures I should be seeing on the Lexia. As it is, at tickover it shows the turbo boost as 1 bar; rev to about 2000 rpm and it sinks to approx 930 - 950 mb.; go to 3000 + rpm and it peaks at app. 1088 mb.

Is there a data page buried somewhere in the repair section of the Citroen manual that has specifications ?

I have also blanked the EGR. I don't see how this would contribute to any problems, but am quite willing to hear otherwise, if it does.

Mike.

[h2ocooler]

No the swirl valves are in the inlet manifold, these 16 valve engines shut off one inlet port to get better power low down then open it around 2500 rpm, it is operated by vacuum and shares its supply with the turbo, if the diaphragm has failed the turbo actuator does not have enough the control the boost.
It might not be the Turbo causing the problems but the swirl valve not working, It SHOULD be located on the end of the cylinder head somewhere with a rod going to a leaver on the manifold, if you search for swirl valve on these forums there will be loads of info on it.

Not sure on the PSA engines but a lot of cars now monitor the MAF and expect to see a drop in flow when the EGR opens, if not it can throw up a fault (my Mercedes was like that)

[KP]

Those figures look low to me. I would take the turbo off and dismantle it and clean the housing and the variable nozzles on it with some intake cleaner or oven cleaner to get the worst of the stuff off them as they could be ceased into a poor position as the turbo should build boost very quickly and then they adjust to keep it at that boost level thru the Rev range.

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Thanks for the info.

I can see these swirl valves listed on the parts list for a 2.2, but can't seem to find a reference to them for the 2.0 136. Am I missing something ? While trawling the parts list, I notice the air inlet appears to have two paths; one via the intercooler and one bypassing it. In the repair section, there is talk of the hot air and cold air intake and respective electrovalves; in the parts listing, they just seem to refer to the 'air doser'. There also appears on the parts list some kind of assembly at the bottom end of the turbo output piping -- the turbo output runs to it and it seems to form part of the air circuit to the manifold. Any offers on its purpose ?

Must admit I find it incredibly frustrating that I can't find a page anywhere that has an overall description of exactly how the fuel / air system is supposed to work, compounded by the fact that they appear to use different terms of reference between the parts list and the repair manual.

My 110 Xantia gets more attractive looking by the day !

Mike.

[Monkeyfeet]

Swirl valves on the 2.2 only. AFAIK
Intercooler is bypassed when it's running a cleaning cycle for the FAP / DPF, helping to get max heat in the filter.
Not sure about pressure readings, can't work out those strange readings.
I've got the EGR blanked too, only difference I noticed was slightly smoother running, and a stop to the smoke when booting it exiting roundabouts. (Might have had a sticking EGR inthe first place though)
Double checked all the usual stuff first? Easily missed hose, intercooler, etc leaks?
I think you're on the right lines checking the turbo itself last, they do look a pain to get at.

[hamster99]

I'd be surprised if the variable geometry vanes in the turbo are sticking.

I replaced the turbo on my C5 last October and it's run fine for the past 23k miles. If I get a chance over the weekend I will hook it up to the lexia and see what pressure readings I am getting so you can at least see how it compares to yours.

Rob

[Jovani]

If you have available Lexia, watching live data engine in Air. inlet circuit, you can see the parameters Turbo pressure seting and Turbo pressure. Under normal operating turbo values ​​move 1:1. The reaction of variable geometry can follow through Turbo position setting and Turbo posittion copy, they are also move 1:1. Best these values ​​to be monitored in test driving. if you have a difference between Turbo pressure seting and Turbo pressuremore than 100mbar or delay the correct pressure , the exhaust will smoke black smoke

[Jovani]

Did some screenshots of the graphics work the turbo - clearly visible late reaching the required pressure:

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Jovani --

Many thanks for your post. Really appreciate that and will be out to have a look at mine again hopefully over the weekend. Maybe I haven't revved mine hard enough, but I haven't seen figures anywhere near the higher values shown on your readings.

Peter ---- long time no speak -- hadn't we used to exchange the odd bit of banter on the XM forum ?

Mike.

[Jovani]

To avoid mistakes, boost pressure is shown as the sum of atmospheric pressure and the pressure of the turbo blow ie if atm. pressure 937mbar + 500mbar turbo, the graph will 1437mbar. Maximum pressure I've seen a real boost pressure 1300mbar (2300mbar on graphic). And up to 1800 bar fuel.

[Peter.N.]

Hi Mike

Likewise, my memory never has been very good but I do remember that user name. Still have an XM estate although its on SORN at the moment, hoping to resurect it one day. Running a C5 and 406 at the moment. How are you doing?

Peter

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Jovani --- thanks for the clarification. Will be back when I have had another go with the Lexia.

Peter -- well, my last on the road XM went about three years ago and up 'til getting this C5 I've had a couple of 110 Xantia estates. Well impressed with the build of the late Xantia; markedly better than this C5 I have, in a number of areas, although access to quite a few things looks a lot better on the C5. I did ponder getting a Jag X type estate, but the cramped cabin and lack of proper suspension were deciders. Given they too use a version of the PSA diesel (I think ?), interesting that they have chain cam drive rather than belts. While I've been getting through the Cits for varying reasons, my trusty works Defender has just kept going and I.m starting to think some bits of the UK motor industry were quietly making some better kit than we were led to believe.

Mike.

[Peter.N.]

Hi Mike

I have looked at the reliability of others, especially diesel engines and have come to the conclusion that PSA make the best ones. My 406 is just coming up to 230k and the C5 to 200k and they both have the original clutches and DMFs - and head gaskets!

I actually prefer the 406 to drive, much sharper handling than the C5 but the C5 wins on comfort and space - so I keep one of each. They will both do 60mpg+ driven gently but I used to get well over 50mpg from the XM on long journeys. I have been retired for 10 years but still seem to be managing 15k per year.

The Ford engines while based on the PSA are not exactly the same, they require all sorts of programming when changing bits that the others don't. I too considered an X type but as you found to little space and to difficult to work on.

Peter