Xantia 1.9TD 1997, Does any one know what this is?

masood_ilyas · Post by **masood_ilyas** » 04 Apr 2011, 21:00

At the end of a tiring Cambelt change I manage to snap a feed from a sensor to the Bosch pump. Does any one know what the purpose of this green sensor is.

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Would this disturbed feed give rise to tractor like noise, or have I missed a tooth on the belt. Fearing worst I have not taken it for a spin yet, though it starts on first kick!
Do AL4s have any timing reference hole for the crankshaft, I could not find one, it being an autobox assumed no flywheel so had to lock the starter ring on the gear box instead. Things were simpler on MK1, this MK2 does not even have an inspection hole on cylinder1 to check for TDC. How does one lock the cam,crank and pump accurately.

Any advice would be greatfully received. thanks

red_dwarfers · Post by **red_dwarfers** » 04 Apr 2011, 21:49

Interesting, there is a green plug around that area coming from one of the two middle injectors, removing this does give the engine a proper tractor noise.
What with it going towards the back of the engine and having that odd end on it I'm thinking an electrovalve has been misplaced as they have ends like that but are usually found at the back of the engine bay next to the cam vacuum pump.
Don't quote me on any of that mind!

citroenxm · Post by **citroenxm** » 04 Apr 2011, 23:13

With u not locking the crank id say u were a tooth out... There is a locking hole on the auto flywheel plate... Yes its not a flywheel. But it is lockable still... Im sure...

As for the valve it looks like its in line with the boost sensor pipe to the top of the pump from the intercooler pipe.. Can u get a more zoomed out picture showing more area??

Paul

citronut · Post by **citronut** » 05 Apr 2011, 07:58

surely the answer would be make a temparary repair to see if it stops the John Dear sound,

regards malcolm

masood_ilyas · Post by **masood_ilyas** » 05 Apr 2011, 18:47

I will Malcolm once it stops raining and blowing.

Here is a zoomed out picture showing indeed that one pipe goes from turbo circuit to the back of this valve and the front if it wern't broken to the fuel pump.

Thanks

Xaccers · Post by **Xaccers** » 05 Apr 2011, 19:30

That's the boost/fuel compensator line or whatever it's called, as the pressure increases with the turbo kicking in, it makes the pump supply more fuel.
For some reason you have an electrovalve in it, which would delay the fuel compensation by preventing boost pressure getting to the diaphram inside the UFO on top of the pipe.
I'm wondering if it's to try and save the autobox from destruction by reducing the acceleration the engine can produce.

Post by **CitroJim** » 05 Apr 2011, 19:43

Xac wrote: I'm wondering if it's to try and save the autobox from destruction by reducing the acceleration the engine can produce.

Yes, that'll be the most likely explanation. Too much torque will shorten the life of the 'box and the electrovalve will act as a sort of boost modulator.

The auto nust have a different ECU. I can have a look at the wiring diagrams for the auto and see if I can find out anything further.

Bypass it completely and see what happens...

citroenxm · Post by **citroenxm** » 05 Apr 2011, 20:06

Well from that then i can tell you two things....

A it will be having no effect on the tractor noise. That is defenatly a tooth on the belt.. Promise you...

B having it disconnected as said above will give you no over fueling as above and slowwwwww accelleration...

It was fitted to an S Plate td auto estate i had in once... So i also suspect its a protector for the auto box... It will be related to a kickdown operation... These remember jim are the al4 box... Not autoadaptive...

Paul

Post by **CitroJim** » 05 Apr 2011, 20:40

Ahh, yes it could be kickdown related. The 4HP20 retards the ignition a little at times to ensure a smooth change and bleeding boost on a TD would achieve much the same thing; a small reduction in power to ensure a smooth change.

citroenxm wrote:These remember jim are the al4 box... Not autoadaptive...

Yes it is, the AL4 is an electronic auto-adaptive... It's not that much different to the 4HP20 in the electronics department.

masood_ilyas · Post by **masood_ilyas** » 06 Apr 2011, 20:12

Citroenxm, Paul you were right, its egg on my face it was indeed a tooth out. I managed to get it right once I went back to my marks I made on the starter ring at the start of this job.
I managed to find the timing hole near the starter but was surprised to find that there were 4 holes on the plate behind where the lockin pin could have gone and most perplexing none of them matched TDC, French idea of a joke I suspect.

As for the turbo boost feed, I have by passed it for the moment so that the electrovalve could be glued back. I dare not leave it in bypassed mode for long given the comments above for the AL4's ability to handle large torques.

Once again very greatful for the all help and advice.

Masood ILYAS