C5 110bhp Diesel Turbo Problem

Rawce · Unread post by **Rawce** » 07 May 2012, 19:04

Hello,

I'm always worried to start off a new topic with a first post, but I've done a search in a couple of the forums and couldn't find anything specific to my problem (other than the Xantia turbo outlet pipe noted here http://www.frenchcarforum.co.uk/forum/v ... =3&t=36569" onclick="window.open(this.href);return false;). Apologies if my search hasn't been thorough enough.

I have a C5 2.0l 110bhp diesel, ex-fleet that was handed down to us when the in-laws repatriated to Spain 18 months ago. It's on 97k and after the crankshaft pulley went in October (£250) and the MOT/cambelt in Feb (£450), the car's started to get rather expensive on me (the in-laws never had a problem with it, typical but we did get it for free).

About 6 weeks ago, I noticed that the turbo seemed to be suffering from a rather long lag. It would kick in, but it would take longer than ususal, and normally only kick in when the revs were so high you'd need to change gear anyway. This has gradually gotten worse, to the point where the turbo doesn't seem to kick in at all. I'm really hoping it's just pulling a vacuum or a solenoid's gone. The turbo never made any death whine and there's no cloud of smoke/pistons coming from the exhaust, so I don't think the turbo itself has gone. Until yesterday, there was no engine warning light...

Yesterday, I got back from holiday and drove from Heathrow to Bath with no turbo at all. It'll get to 70, but you can't go above that on the flat and uphill can be a struggle to maintain. On the M25 I heard a noise which sounded like the undertray scraping on the floor, pulled over and indeed the undertray had come free at the front and was flapping. I'm ebaying for some replacement plugs/fittings to resecure it. However, as I didn't have any tie wraps, I bungeed the tray up so it touched the bumper to get me home. Almost immediately after doing this the engine warning light came on (amber). I pulled over again, but saw nothing obvious so I doubt hanging the bungee off the battery/leccy gizmo box covers and round the air inlet pipe would do anything. The bungee was rubbing on the radiator, but not enough to burn through or do anything. Therefore, I'm assuming the warning light came on because the turbo (or, I'm hoping, the ability to provide boost) has finally stopped working.

Therefore, I'm looking for help on answering the following questions:

Do the symptoms sound like a split pipe or a solenoid?

How many pipes am I looking for; inlet, outlet and a small vacuum hose as mentioned in the post linked above?

Is there anyway of diagnosing the solenoid?

Is the warning light related to a gracefully declining turbo giving up the ghost?

Should I just take it to my local garage to get it properly diagnosed?

As mentioned above, I'm loathe to spend more money than necessary now the bills are getting as high as the car's worth. I always used to sort cars out myself (unless it was electrical - that dark magic is best left to the shamans if you ask me) but a lack of garage/off street parking has limited that to all but the basics.

Any help would be greatly appreciated before I throw in the towel and dust off the debit card.

Cheers,

Ross.

Unread post by **CitroJim** » 07 May 2012, 19:15

Ross, a perfect first post and welcome

If al the pipes are good and the intercooler is intact, signified by it being dry and not covered in oil at its base, then the next obvious candidate is the MAF sensor. They die quietly with much of the symptoms you describe.

There's no quick checks to be done to diagnose it but some say if you disconnect the MAF sensor (the fat tube just after the airbox with an electrical connector on it) and the car runs better then the MAF is suspect.

Better much to find a member who lives locally to you who has a Lexia Diagnostic kit, there's a list in the Supersticky area of this forum, and have a diagnostic run. That'll pin-point the area of the trouble and can test things like the turbo and EGR electrovalves.

A Lexia takes all the guesswork out of it...

Unread post by **citroenxm** » 07 May 2012, 19:30

Id me more inclinde to point my finger at the Vaccuum electro valve gone faulty!! They sit by the passenger strut top on the bulk head. Theres two vacuum valves - One controls the waste gate, the other EGR exhaust valve.

The vaccum NEEDS to be applied to the Waste gate to CLOSE it up... If theres no vaccum on it, the wastegate stays open and hence no boost!

I had this on a Xantia with the same engine.. and it was one of these valves. Theres no real way to test them, but you could, which is what I did, swap the EGR one with the turbo one.. They do the same job.

Thats what Id do first. MAKE sure all vac pipes go back exactly the same way on each valve. The basic operation is a constant vaccum is present, this closes the waste gate. Then while driving the ECU monitors the turbo pressure via the pressure sensor on the intercooler.. When the Max set value is reached, the ECU switch's the Electro Vac Valve and the vaccum is released from the waste gate and it opens...

The magement light WONT come on because its not sensing an OVER boost, so theres no danger.

Paul

Rawce · Unread post by **Rawce** » 07 May 2012, 19:54

Hah, I always thought those diagnostic tools would be hulking, ruggedised Windows 98 laptops costing thousands. Maybe I should have a chat with the chap from Warminster. Thanks for the suggestion.

First I'll have a proper rummage through the pipes and check for anything obvious - visible cracks and oil. Would getting my wife to rev the engine help identify any sucking noises a cracked pipe might create?

I might take a couple of pics and hoy them up here to help make sure I'm looking at the right pipes and valves.

Thanks all.

Rawce · Unread post by **Rawce** » 07 May 2012, 19:57

Paul, any probs with the EGR system if I put the duff wastegate one on it or would it just not recirculate the exhaust?

Unread post by **CitroJim** » 07 May 2012, 19:58

Good thinking Paul

I misread the OPs post and thought he'd checked all the pipes and thus I was looking for something else to account for the problem....

Mind on other things...

Rawce wrote:Hah, I always thought those diagnostic tools would be hulking, ruggedised Windows 98 laptops costing thousands. Maybe I should have a chat with the chap from Warminster. Thanks for the suggestion.

They used to be but now they are available at quite reasonable cost as Chinese Copies of the genuine thing. We call them Chixias. They run quite sweetly on any XP laptop.

Unread post by **citroenxm** » 07 May 2012, 20:02

It shouldnt do. Doesnt do on the Xantias. Theres no electrical connection to the EGR just the vaccum pipe... Rev the engine. The throttle is behind the air cleaner output pipe... I think.. You should see the intercooler pipe expand.

These valves DO NOT show up as a fault either.. If you have a Lexia session, you can go into "Live Parameter Readings" and this physically shows you what the ECU sees, in that what boost your getting. My bet is STILL instatant on the Vaccume Electronic valve, above the servo..

Rawce · Unread post by **Rawce** » 07 May 2012, 20:02

I've only had a cursory glance at the pipes for anything obvious (split, hanging off, not there, on fire, etc.) but not a thorough rummage. I shall do that first then see how I go. Cheers for the suggestions though all.

Rawce · Unread post by **Rawce** » 07 May 2012, 20:12

Are they a faff to change other than lining the pipes up properly? Are they costly from a dealer or will a scrappy one do for another 50k miles?

Gibbo2286 · Unread post by **Gibbo2286** » 08 May 2012, 09:14

If you want to do a quick check of the MAF sensor pop it off and have a look down the tube, you should see what looks like two light bulb filaments, they get green corrosion on them and usually fail when one of the filaments drops out.

Chris570 · Unread post by **Chris570** » 08 May 2012, 09:37

citroenxm wrote:It shouldnt do. Doesnt do on the Xantias. Theres no electrical connection to the EGR just the vaccum pipe... Rev the engine. The throttle is behind the air cleaner output pipe... I think.. You should see the intercooler pipe expand.

These valves DO NOT show up as a fault either.. If you have a Lexia session, you can go into "Live Parameter Readings" and this physically shows you what the ECU sees, in that what boost your getting. My bet is STILL instatant on the Vaccume Electronic valve, above the servo..

I'm wondering if we have more xantia s2 fun and games here.

I've had the control valve show as a fault twice now on my HDi, i've just cleared the codes and gone on as normal (20k later she's still happy)

I've also had the EML on because of the turbo boost being too LOW when i had a split intercooler to intake hose.

I think maybe different S/W versions maybe at the route of this.

Sorry to contradict you but just want to make sure nothing is ruled out here as I have seen these on my own engine

Rawce · Unread post by **Rawce** » 08 May 2012, 20:49

Cheers for the suggestions all. I'll be taking photos tomorrow night and have a good check of all the obvious pipes.

Rawce · Unread post by **Rawce** » 10 May 2012, 21:24

Had a look at the obvious pipes (into and out of the inter cooler) but tbh I'm not sure what others I should be checking. I guess the best bet is for me to bite the bullet and stump up at the local garage. I don't have the facilities or knowledge to really be getting involved in too much anymore.

Once I've remortgaged a kidney to pay for it, I'll let you know the outcome in case it's of use to others.

Cheers,

Ross.

Rawce · Unread post by **Rawce** » 14 May 2012, 22:50

Garage Update.

Codes point to the MAF, so a new one is being fitted. Also, there was water in the air filter so they're drilling a drain hole and replacing the filter.

Hopefully that'll cure it!

Rawce · Unread post by **Rawce** » 16 May 2012, 19:05

MAF and air filter both changed and power is restored. Hopefully a good run to Bristol Airport to pick up the Sister in Law will help blow away any sooty cobwebs. Hopefully this is of some use to someone in the future!

Cheers for all your help,

Ross.

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