synergie still with running problems!

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
petherwins
Posts: 16
Joined: 30 Jan 2008, 00:22
Location: cornwall
My Cars:

synergie still with running problems!

Post by petherwins »

Hi Jim,not sure if this is the right way of doing things on this forum so hope you dont mind me sending you a PM
I've still got running problems with my synergie.
As I said in my last post tested intercooler and back in,fitted new fuel filter and still the same.Today I put a pressure guage on small pipe from turbo pipe (which goes to top of pump) no reading on tickover,approx .45 bar at 4000ish revs.Also took it out for a spin with this pipe blanked and it seemed to make no difference? Also checked needle lift and got a reading of approx 100 ohms,disconnected it while running and it made no difference!
Do you have any ideas I could check next and is the unit on top of pump something that can be taken apart or checked in some way.
As I said above hope you dont mind me asking you but was well impressed with your previous reply even though the detail on pump was a bit over my head! thanks and hope to hear from you soon,regards Alan
petherwins
Posts: 16
Joined: 30 Jan 2008, 00:22
Location: cornwall
My Cars:

Post by petherwins »

Cheers again Jim,I will test under load tomorrow,hopefully run a length of pipe inside and take it for a spin to see what pressure I get.
I'm sure the guage is not calibrated so reading will be more or less.thanks Alan
User avatar
CitroJim
A very naughty boy
Posts: 49526
Joined: 30 Apr 2005, 23:33
Location: Paggers
My Cars: Bluebell the AX, Polly the C3 Picasso, Pix the Nissan Pixo, Propel the duathlon bike, TCR Pro the road bike and Fuji the TT bike...
x 6160
Contact:

Post by CitroJim »

This is a continuation of this thread. Alan originally PM'd me and I asked that it be posted as it's an intersting problem worthy of being shared.

To recap, Alan's 1.9TD engine is faltering at full throttle/full load.

Alan,

Thanks for posting this. I said I've been thinking and I have :wink:

The fact that disconnecting the pipe between the turbo hose and the top of the pump (boost sense) makes no difference would appear to suggest there's a problem generating boost. .045bar of boost at 400rpm seems a tad on the low side to me but full boost will only be developed when the engine is uder load at 4000rpm and not off-load. That said, it is wort checking the rest of the turbo hosing, especially that on the hot side of the turbo for air leaks. A leak anywhere can have a dramatic effect. Another possibility is that your turbo waste gate is stuck partially open or is opening too soon. One thing to check here is that the rubber pipe to the waste gate actuator is intact and not perished. they frequently do, right on the conection to the actuator and again this will spoil boot generation. Access is not easy though.

Another possibility is that of a partially blocked exhaust. That will both cause low boost (too much back-pressure) and a lack of performance at high revs/load. The kost likely candidate is the cat. A cat is not a legal requirement on a diesel in the UK and it can be bypassed to useful performance and economy effect. There may be a bypass pipe available for your car or a friendly exhaust man may be willing to erm, make a small modification to your cat to erm, de-cat it. The back-box has been known to be a cause of restriction as well although if this is the snag, the cat is the most likely.

It is odd that disconnecting the needle lift sensor makes no difference. It normally makes a 1.9TD run really roughly. I'd also try disconnecting the TDC sensor (brown connector under the airbox) and see if this makes a difference. Boths ensors are essential for the ECU to ne able to calculate timing for the pump and if they are in error the pump failsafes to a fully retarded condition (usually) although sometimes they go the other way and the engine knocks.

If it still makes no sense, it'll be essential to have Lexia Diagnostics performed to ensure the ECU timing instructions are being carried out faithfully by the pump. On a Lexia you can see the set ECU timing figure and the actual pump timing next to it. If these don't track each other faithfully, there is either a sensor problem or an internal pump fault. If there is a sensor fault, this will be recorded in the ECU. Timing on a diesel is highly critical and it only needs to be a bit out to really kill off performance. If the TDC or Needle lift sensor isare both duff, the tacho will stop working. So a good test is to disconnect each in turn and seeing if the tacho stops working at all and/or the engine management light flashes on.

The unit on top of the pump is the load sensor and is nothing more than a potentiometer that measures the throttle position. By knowing how far the throttle is open for a given rpm and road speed, the ECU can work out engine load and select an appropraite timing vale for setting on the pump. The sensor can be checked with an ohmmeter although I never have actually. They're normally 100% reliable and a Lexia will soon tell you if they're iffy anyway.

Hope that helps Alan. Let us know how it goes please as it's rather an interesting problem.
Jim

Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
petherwins
Posts: 16
Joined: 30 Jan 2008, 00:22
Location: cornwall
My Cars:

Post by petherwins »

Thanks once again Jim,
did a test today under load and getting approx 1bar maximum.
There is no cat .
checked actuator,there's only a short rubber pipe (50mm long) seems ok.
Got me thinking when you said about needle lift and tdc sensor could retard pump timing,how does that work? Only when I removed gearbox the tdc sensor wire was cut off! The replacement box I fitted (which seems like months ago now)allready had this sensor fitted so I used this one.
So previously it was not working,would this retard pump timing and remain like this even though sensor is now working?With this in my mindl
Looking at pump flange this morning and somebody has scribed a mark which dosent line up with factory mark on pump.
As I'm not sleeping too well with all this in my head I thought I would try mmoving pump timing!
chopped and welded a spanner to get to lower nut (only to find it was loose) moved pump clockwise by about 2mm looking from near side.
took out for another test and seems to have vastly improved!!!
not sure if this is the answer?
ps.just remembered I also ran without needle lift connected and it made no difference atall,cheers Alan
petherwins
Posts: 16
Joined: 30 Jan 2008, 00:22
Location: cornwall
My Cars:

Post by petherwins »

After thinking a bit more on the above,my thoughts are,
Maybe in its previous life the TDC sensor packed up and with a air leak on intercooler somebody decided to adjust pump timing.
Its running well now without holding back(allthough not any quicker),just not sure if pump timing is correct?Is there any way of knowing without specialist equipment?
thanks in advance,Alan
User avatar
CitroJim
A very naughty boy
Posts: 49526
Joined: 30 Apr 2005, 23:33
Location: Paggers
My Cars: Bluebell the AX, Polly the C3 Picasso, Pix the Nissan Pixo, Propel the duathlon bike, TCR Pro the road bike and Fuji the TT bike...
x 6160
Contact:

Post by CitroJim »

Ahhh, a little more of the jigsaw falls into place Alan :D

Sounds like a bodger has been at work. As I say, if the timing sensor signals are missing or corrupt, the ECU will failsafe the pump to a fully retarded timing condition.

The TDC sensor being chopped suggests that the ECU has gone into failsafe and to compensate for the grossly retarded timing, said bodger has adjusted the pump timing :twisted: :twisted:

Problem with doing this is you then have no automatic advance with engine speed/load and the timing will be optimum nowhere.

Does your K (Engine Management) light ever come on as under sensor failure it should. It should also come on when the ignition is first switched on and then extinguish as soon as the engine starts.

I'd not be surprised if the same bodger has either removed the bulb or chopped the wire and connected to another light that comes on and then goes off when the engine starts :twisted:

He may also have disconnected the blue plug on the pump controlling the timing servo.

The pump will need to be repositioned and the timing fidelity checked with a Lexia as I described earlier. There is a complex procedure for setting the pump to the correct initial position to ensure the full timing swing is available. If you are lucky, you should be able to see old washer marks to show where it was originally.

Sounds like there may still be issues with the ECU though. It may have died. Again, a Lexia is essential to diagnose this. Luckily, they're quite readily available in scrapyars relatively cheaply and are not keyed to any immobiliser that may be fitted.

Hope that makes sense Alan....
Jim

Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
petherwins
Posts: 16
Joined: 30 Jan 2008, 00:22
Location: cornwall
My Cars:

Post by petherwins »

Not seen any managment light,will check that out.
Not heard of LEXIA before,my nephew has access to SNAP ON SOLARIS,BOSCH KTS520 AND PPS,would any of these do the same job?
User avatar
CitroJim
A very naughty boy
Posts: 49526
Joined: 30 Apr 2005, 23:33
Location: Paggers
My Cars: Bluebell the AX, Polly the C3 Picasso, Pix the Nissan Pixo, Propel the duathlon bike, TCR Pro the road bike and Fuji the TT bike...
x 6160
Contact:

Post by CitroJim »

The Lexia is the pukka Citroen diagnostic tool Alan and likely, knowing Citroen, it's the only tool that will do a full diagnostic on the ECU.

I'm not sure about the one you've mentioned. Worth a go but don't be surprised if they just sit and sulk when confronted by a Citroen...
Jim

Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
Post Reply