Idles but won't rev unless on boost. Diesel Xantia 1.9TD SX

[skysurfer1]

I've had my Xantia for over 6 years and done 95,000 of the 160,000 miles on it. Generally it's been little trouble but the day before Christmas eve it developed a problem and had to be towed home.

It's a 1997 Citroen Xantia 1.9TD SX (Turbo Diesel) with keypad imobiliser:

It will start (rather reluctantly) and idle (750rpm - it was normally 1000rpm) but the revs hardly change at all when the throttle arm moves on the injector pump, remaining at a slow idle even at full throttle.
(No unusual noise, quite smooth running).

If the injector pump detects turbo boost pressure then it will pick up and rev fairly normally, responding to the throttle arm on the pump.
Obviously there is no boost at idle, but it can be initiated in several ways:
1) Using ether (Easy-Start aerosol) to get the revs up over 2000 rpm.
2) Rolling the car down a hill and releasing the clutch in gear to get the revs up over 2000 rpm.
3) Connect a tube to the atmospheric pressure vent on the underside of the injector pump boost sensing diaphragm. Suck very hard on the tube with the engine running. After about 30 seconds the revs will build to over 2000 rpm and there is then no need to suck the tube.

So long as the revs are kept up then it will run indefinately and will respond to the throttle. I have driven the car over 10 miles like this. I don't think it has as much max power as it should. If climbing a hill the revs can be held as low as 1700rpm without dying back to idle but if there is no load on the engine then it will die back to idle if the revs are ever allowed to fall below 2000rpm.

It doesn't actually require turbo boost to run, it just needs the injector pump to think there is boost! I've run it with the inlet manifold disconnected from the intercooler ducting and squirted Easy Start into the manifold to get the revs up. Once over 2000rpm it can be reved on the throttle and no more Easy Start spray is needed.

When this fault developed I had run very low on diesel and it felt as though it was loosing power for the last half mile before filling up with diesel.
It was still low on power after filling up. The idle was slower than normal and the throttle response was not normal. (Needed to press pedal further before it would rev). I kept the revs fairly high for the next mile before parking at the shop we were going to. When I came out of the shop and started the engine it would only idle and did not rev in response to the throttle...

On getting the car towed home, I changed the fuel filter. It didn't appear to be particularly blocked and there wasn't much residue in the filter container.
There was no water in the filter container. I could easily pump fuel into the filter chamber with the primer bulb before I put the lid on it with the new filter. I slackened the union at the injector pump inlet and could pump fuel free of air from it with the primer bulb. With the engine running I cracked the pipe connections at 2 of the injectors (1 at a time - couldn't get to the other 2). The revs dropped and the idle slightly rough and fuel leaked out for each one. With the engine stopped but the ignition on and the keypad code entered I slackened the injector diesel return union and could pump air free fuel from there with the primer bulb.

After looking at diagrams and descriptions of how the boost sensing works, I removed the dust cap from the top of the boost sensor diaphragm and adjusted the screw down by 3 turns. This made no difference. I then removed the 4 torx screws and removed the top of the boost sensor and its diaphragm along with the shaft with the offset cone on the end. The pin that rides on the cone was not visible, but it did pop into the central hole when the throttle was opened. I put a pen down the hole as a stop to prevent the pin from being pushed through too far and falling into the central hole where the cone should be. With this mod the revs now pick up from idle without any further trickery!
Even with this temporary modification I can't continously HOLD the revs anywhere between 800 and 1600rpm although it idles ok at about 800 and I can rev it anywhere up to about 4800 and hold at any constant revs I want at 1600rpm or greater!

Is it definately the injector pump? Is there anything else I can dismantle/check with the pump on the engine?
Could it be the cam belt slipped? (This has happened before on this car and it ran ok then but it had more "diesel" noise than usual and the engine warning light was on. After running for some days it probably slipped another tooth and it would not start). I guess there could be different simptoms depending on which pulley slips on the cambelt. (Crankshaft/Injector/Camshaft). I've never managed to find the timing hole in the bell housing/flywheel on this engine. Is it just above the starter motor? The cam belt has about 40,000 on it.

Could it be something electrical? This injector pump has a throttle pot on the top of the throttle shaft. There is a sense wire on one of the 4 injectors.
There are 4 wires going into the end of the pump. (I think this is to do with the keypad imobiliser).

The injector pump is Bosch 0 460 494 427 / R 601-2 / XUD BP 02

Thanks for any ideas!

[Peter.N.]

Sorry - Posted in error

[KevMayer]

Did you actually run out of diesel ? I believe the lack of diesel can damage a pump. It seems like yours has suffered some kind of set back which may be due to the lack of diesel lubrication inside the pump. It sounds like something has gone faulty around the governor/linkages which control the position of the ring around the injection shaft.

I used to have a 1.9 td Xantia and I changed my diesel pump in the end. I managed to buy a second hand one off ebay for 15 quid. So, if it is your pump thats faulty, which it sounds very likely, then it shouldn't cost too much to swap the pump. I did it myself. All i needed was a dial gauge to set up the timing and it seemed pretty easy.

The ecu on these pumps controls a solenoid under the pump which controls pump injection timing. It uses inputs from the throttle position potentiometer and the wiring from the injector which has a lift sensor. This gives feedback to the ecu to tell it what the timing angle is.

The timing hole in the flywheel is accessed from underneath the starter motor. When I did my pump swap I couldn't find it so I took my starter motor off. It's obvious where it is once you've done this. A 6mm drill or allen key will fit a treat. I used an allen key.

Cheers.. Kev

[jeremy]

I agree it does sound like the injection pump BUT that the cambelt has slipped before makes me wonder what caused that as its not a normal occurrence.

Firstly I'd check the timing - and it sounds as though you have the necessary kit. The flywheel hole is not easy to find - its tucked down behind the starter. When I did my BX I had a kit with a nicely bent piece of 8mm bar - which I could not get in. I measured it at 8.03 mm - and could only get a 7.5mm drill through the hole! I actually used a junior hacksaw frame as recommended by someone on here which was just about perfect. It is slightly slack but as the only adjustment on the belt is the tensioner which is on the trailing side the slack would not affect the timing as the slack is much less than 1 tooth on the belt.

The additional fuel device responds to inlet manifold pressure not engine revs - so its perfectly possible to run the thing at max revs but not under load - and have no extra fuel delivered. In fact the fuel shuts off altogether on a trailing throttle.

I am assuming that NO air is getting into the injection pump.

You make no mention of smoke - does that mean than none is ever emitted? If this is so its unusual and significant.

[skysurfer1]

Thanks for the info on locating the timing hole. I was a bit nervous about poking about behind the starter motor as I hadn't removed the battery as I don't know the radio code

Kev -
It didn't fully run out of diesel. It was still running when I stopped the engine to re-fill with diesel and it started ok after filling up. It did feel like it was running out though and I put about 71litres in! (Previous max fill up was 67 litres).

I'm thinking that the lever that presses against end of the govenor may have bent. Particularly if the lever was worn by the rotating tip of the govenor without fuel to lubricate it. I'm suprised it is this delicate as I ran my Nissan van out of diesel 3 times with no damage (300 miles max range an broken fuel guage )

The best price I've got so far is 72GBP for a pump, which isn't too bad. I'm holding back from buying it as I'm not sure about the imobiliser that is under a shear bolt protected metal cover that hides the stop solinoid. I think the imobiliser keypad code may be held in the pump. So if I buy a second hand pump I would need to know the keypad code for it. Did your car have the keypad imobiliser?

Is it possible I could get away with a digital vernier guage to set the timing rather than a dial guage?


Jeremy -
When the cam belt slipped (about 4 years ago) it was because I had allowed the auxillary belt to get in very poor condition and half of the auxillary belt shredded itself with some of it getting under the cam belt cover at the crankshaft pulleys causing the cambelt to jump a tooth.
If they hardly ever slip without this sort of incident then it probably hasn't slipped. Obviously I'll be a bit more suspicious if there is something wrong with cambelt condition or tension when I take a look at it.

I don't think it's air getting in. The behaviour is entirely repeatable and doesn't vary in any way. Nothing changes if I pump the primer bulb while on idle or when trying to rev the engine.

Smoke level is fairly normal. (i.e. not much smoke) There was a noticable black soot mark on the driveway when I had run it for a long time without moving the car.


I'd like to hear any other comments on this fault please.

Alan.

[skysurfer1]

..

[lolingram]

I used to have a 1.9 td Xantia and I changed my diesel pump in the end. I managed to buy a second hand one off ebay for 15 quid. So, if it is your pump thats faulty, which it sounds very likely, then it shouldn't cost too much to swap the pump. I did it myself. All i needed was a dial gauge to set up the timing and it seemed pretty easy.

The ecu on these pumps controls a solenoid under the pump which controls pump injection timing. It uses inputs from the throttle position potentiometer and the wiring from the injector which has a lift sensor. This gives feedback to the ecu to tell it what the timing angle is.

_________________________

I have a 1997 1.9 XUD TD Xantia (with ECU) which seems to not give full grunt anymore (although the turbo pressure is OK - the flexi pipes swell when the throttle is opened up), what effect on power could a malfunctioning ECU/Throttle sensor/Timing solenoid have - anything really significant powerwise?

Thanks in advance for any thoughts.

[lolingram]

I used to have a 1.9 td Xantia and I changed my diesel pump in the end. I managed to buy a second hand one off ebay for 15 quid. So, if it is your pump thats faulty, which it sounds very likely, then it shouldn't cost too much to swap the pump. I did it myself. All i needed was a dial gauge to set up the timing and it seemed pretty easy.

The ecu on these pumps controls a solenoid under the pump which controls pump injection timing. It uses inputs from the throttle position potentiometer and the wiring from the injector which has a lift sensor. This gives feedback to the ecu to tell it what the timing angle is.

_________________________

I have a 1997 1.9 XUD TD Xantia (with ECU) which seems to not give full grunt anymore (although the turbo pressure is OK - the flexi pipes swell when the throttle is opened up), what effect on power could a malfunctioning ECU/Throttle sensor/Timing solenoid have - anything really significant powerwise?

Thanks in advance for any thoughts.

[lolingram]

I used to have a 1.9 td Xantia and I changed my diesel pump in the end. I managed to buy a second hand one off ebay for 15 quid. So, if it is your pump thats faulty, which it sounds very likely, then it shouldn't cost too much to swap the pump. I did it myself. All i needed was a dial gauge to set up the timing and it seemed pretty easy.

The ecu on these pumps controls a solenoid under the pump which controls pump injection timing. It uses inputs from the throttle position potentiometer and the wiring from the injector which has a lift sensor. This gives feedback to the ecu to tell it what the timing angle is.

_________________________

I have a 1997 1.9 XUD TD Xantia (with ECU) which seems to not give full grunt anymore (although the turbo pressure is OK - the flexi pipes swell when the throttle is opened up), what effect on power could a malfunctioning ECU/Throttle sensor/Timing solenoid have - anything really significant powerwise?

Thanks in advance for any thoughts.

[lolingram]

I used to have a 1.9 td Xantia and I changed my diesel pump in the end. I managed to buy a second hand one off ebay for 15 quid. So, if it is your pump thats faulty, which it sounds very likely, then it shouldn't cost too much to swap the pump. I did it myself. All i needed was a dial gauge to set up the timing and it seemed pretty easy.

The ecu on these pumps controls a solenoid under the pump which controls pump injection timing. It uses inputs from the throttle position potentiometer and the wiring from the injector which has a lift sensor. This gives feedback to the ecu to tell it what the timing angle is.

_________________________

I have a 1997 1.9 XUD TD Xantia (with ECU) which seems to not give full grunt anymore (although the turbo pressure is OK - the flexi pipes swell when the throttle is opened up), what effect on power could a malfunctioning ECU/Throttle sensor/Timing solenoid have - anything really significant powerwise?

Thanks in advance for any thoughts.

[lolingram]

I have a 1997 1.9 XUD TD Xantia (with ECU) which seems to not give full grunt anymore (although the turbo pressure is OK - the flexi pipes swell when the throttle is opened up), what effect on power could a malfunctioning ECU/Throttle sensor/Timing solenoid have - anything really significant powerwise?

Sorry for the multiple posts - I was given a 'send error' each time!

[KevMayer]

My previous pump did have an imobiliser + throttle pos sensor etc.

The pump I fitted was a previous model of Bosch which was just mechanical. No imobiliser or throttle position sensor. It was just what I wanted. It had automatic timing adjustment (vane pump diesel pressure pushing against a spring to push the roller ring. just speed dependant). I looked for it deliberately because I'd had a history of poor performance and was convinced it was faulty pump timing control.

Once I fitted the old pump it gave me better performance and slightly better economy. It ran better than ever.

Then what did I do. I traded the car in for a C5. What a waste of time eh ??

Back to the topic. To time the pump you remove the end cap in the middle of the 4 injector connections. you then need something which is sensitive and will swing backwards and forwards as the pump shaft goes in and out as you turn the crank shaft. A dial gauge is ideal because it auto returns under gentle spring tension. I don't know if you'd get the same performance from a digital vernier.

I still have my old Bosch pump. I took a few things off it to enable me to fit the older pump but nothing major and it could be made up with bits from your pump. I also know what the imobiliser code was (4544).

Are you anywhere near Staffordshire ? You can have it for nothing.

edit:- Just remebered. The problem with the Bosch pump was a faulty throttle position sensor. I checked it with a multimeter and it had a dead band. The pump itself was great and always started first time.

[jeremy]

This fault is curious and unusual.

Forgive me if some of what I write is very obvious.

Diesels run ofn the principle of free air - which basically means that the engine speed is purely dependant on the quantity of fuel injected. Yours idles slowly and will do little more unless it is tricked with the boost additional fuel device. When it runs there is no particular smoking problem

Faults could be:
Mechanical - ie valves or something - would have less power on one cylinder - so engine would have a beat - and would tend to produce smoke - probably white. Head gasket failure on one would produce a beat - and pressure in the cooling etc. - Break between 2 cylinders - basically won't run - will start with extreme difficulty and run at high revs only (happened to me)

Timing - generally odd sounding - and smoke.

Interestingly I think diesel pumps start on full delivery and the governing mechanism shuts them down. The extra fuel device is something that simply allows the pump to deliver excess fuel in the right circumstances (ie when there is boost)

So it looks as though the pump isn't delivering enough fuel - and that basically the governing mechanism has stuck or become damaged. The pumping bit would seem OK as it can deliver fuel - and the injectors would seem OK as well.

This is unusual as injection pumps are well engineered and capable of truly enormous mileages. Running a little dry doesn't normally seem to damage them as there probably is sufficient fuel remaining to lubricate it.

I'm not sure where the stop solenoid fits into this but imagine it opens a port in the system somewhere which causes the governor to shut on a Roto-diesel and may have a more mechanical operation on a Bosch.

The Roto-Diesel uses fuel pressure to control its governor - which means that if it gets air in it the engine will runaway - as the governor defaults to full power. The Bosch governor is mechanical.

[jgra1]

hi sorry I haven't had time to read all of the postings..

I have a Immobiliser style pump for a 1.9 TD..(with the throttle potentiometer)

I am in Sussex.. can post?
John G

[skysurfer1]

Are you anywhere near Staffordshire ? You can have it for nothing.

Kev,
Now you've really got my attention See my PM/Email.

Interesting that you say your Xantia was lacking in power. So is (was) mine compared with one I've driven that's a year older and has no electronics on the injector pump. I'd always assumed it was the catalytic converter that mine has (1997/P) which isn't on the older Xantia (N) or that the turbo boost pressure is low or the intercooler partially blocked. (Unlikely as the injector pump senses boost pressure before the intercooler, so I'm sure it would inject too much fuel during boost if the intercooler was restricted, making an obvious amount of exhaust soot).

Did the Xantia where you fitted the older pump have a Cat? Did it pass an MOT (UK) exhaust emissions test after the new pump was fitted?

On my Xantia (1997/P) there is a vacuum pump on the end of the camshaft that links to two solenoid valves. The outlets of both of these are disconnected since before I owned the car. (Bought in 2000, 95,000 miles ago). One of these is for the cold idle speed advance. The other vacuum solenoid valve I thought was to control the mid range turbo boost but on re-reading Haynes, they say it is EGR (exhaust gas recirculation), although if it is I can't see where the exhaust gas is being introduced into the intake system.

I think having the high idle tube disconnected has left mine running at high idle all the time. (About 1000 rpm). A side effect of this being disconnected for 6 to 9 years is that I the high idle arm on the pump is now locked solid so I hope that isn't one of the parts you removed from your old pump is it Kev? However since the recent fault it is idling below 800rpm. (And the high idle arm is still seized solid).

It's interesting that the older pump gives both noticeably more power and slightly better economy - as you say it can only be that the timing was not right. You think the problem with the lack of power with your old pump was the throttle pot, but you didn't discover this until after you'd changed to the older pump so you never ran the original pump with the pot fixed - Is this correct?
I need to check my throttle pot as if mine is faulty too there won't be a good one between the two pumps!
With the old injector pump and its faulty throttle pot, was the power just not as good as you would like? (As mine has always been). Or was it well down? (Not really drivable).

Just so I'm sure my ECU will be compatible with your original pump - How many electrical connections are there on the pump? As far as I can see mine just has the 3 wires on the throttle pot and another 4 (I think) wires going under a black plastic cover on the outlet end of the pump. I thought these were just for the immobiliser/stop solenoid but are they also for the timing advance as well or are there connections going in somewhere that I haven’t found yet for that?
Do the numbers on your pump match mine? (See first post in this thread).

I have taken the pot off the top of my injector pump during my recent investigations and moved it independently of the throttle at idle and at high revs. There is barely any change in the way the engine runs if I hold the engine at particular revs and sweep the pot from end to end of its travel. From this I had assumed that it was just there to control the EGR (which has always had its vacuum tube disconnected anyway on my car).
Perhaps my pot is also faulty (probably not my only problem if it is) or it only effects things when the ECU detects that the engine is loaded. (i.e. the pot shows the ECU a high throttle setting but the crankshaft sensor or injector lift sensor shows the ECU that revs are being held low by the engine being loaded).

Jeremy,
Thanks for your general analyses of possible causes.
I need to run it again and check for cooling system pressurisation etc. before I start taking the pump off but it is running so smooth that I doubt any problem with valves or head gasket. It is difficult to start but I've put this down to lack of fuel. I use the glowplugs twice then turn it over and it fires with very little power so I have to keep the starter going for a few seconds until it is running well enough to keep going on its own. I think this is just that the governor is not working properly. It should be delivering lots of fuel until the engine is up to full idle speed but I don't think its doing this any more with this fault. It is also easy to stall the engine when driving which implies the governor isn't capable of increasing the fuel supply much at idle. However it does appear to govern correctly at max revs with no load.

The governor and governor springs are in a higher part of the pump than the pumping piston so perhaps the air accumulates here when running out of fuel. The high pressure pump, lower down still gets fuel and is keeping the engine running but the governor higher in the pump is running in air with no lubrication. I'm surprised that this is enough to damage the pump, particularly as I was driving slowly/gently at the time. Perhaps the pump had some previous weakness that made it susceptible. (I ran my Nissan van out of fuel 3 times, once at 60+ mph with no damage - The fuel gauge didn't work ).

As I understand it, on the Bosch the stop solenoid blocks the fuel passage to the high pressure piston rather than interacting with the throttle sleeve.


I'd still like to hear comments from anyone who has seen a problem like mine (see the first post in this thread) and has fixed it. Or even what they tried that didn't fix it might be some help too!

Alan (Probably changing an injector pump soon )