Xantia HDi noise under acceleration

[Synth1983]

Sorry, another question I'm afraid!

My new Xantia makes a bit of a rattle under acceleration then once over 3k it stops. I've read various things ranging from it just being something the HDi does, through to worn injectors. My old Xantia HDi didn't do this at all which makes me wonder whether it could be the latter. I'm guessing replacing injectors is an expensive affair and not really one I would like to contemplate on a relatively cheap car. On the other hand the noise is bugging me a bit and ideally I'd like it sorted. Any suggestions most welcomed!

[charentejohn]

I asked a similar question and these were the replies http://www.frenchcarforum.co.uk/forum/v ... =3&t=38278" onclick="window.open(this.href);return false;

Sounds like injectors if it cuts out after 3200rpm as mine does. Maybe just a good high strength (double dose ?) of injector cleaner will help.
Mine is noisy under heavy acceleration until it reaches working temp then can only just be heard. I did use one lot of Forte injector cleaner though and that did help a bit. Any branded one should do, I usually use tha amount meant for a full tank and put it in a half full tank. Then when near empty I fill up and add another dose.

[CitroSwede]

To 99% is one or several injectors at fault.
The engine cuts the pre-injection off at 3,200rpm, which is when the 3rd piston on the HP pump is activated.
If an injector is bad, the pre-injection phase which is supposed to be the 40ms pulse/ 1cubic mm, will become much bigger and is "pinked" in the combustion chamber, not "showered", if you understand what i mean. The only solution is probably to listen which incectors that clatters, and change them.

A good description from a user on the peugeot forum:
"The ecu uses pilot or pre - injection from 2k rpm to 3.2k rpm, then turns it off. What goes wrong is the worn injector allows fuel from the pressure chamber to leak up to the control chamber and hold the solenoid valve open too long or make it shut slowly, which makes the supposed tiny (1ml) pilot injection turn into a full blown spray - which is obviously wrong in timing terms,
as it forces strong pre-ignition and an early combustion bang (clatter) in the affected cylinder, and hence you are hearing the cylinder not the injector itself. It is "pinking" heavily, which to a TDI / HDI just means the timing is advanced on that one cylinder due to the leaking injector.

A leakback test then shows which injectors are not admitting full pressure to the nozzle but leaking back into the control chamber and hence out to the leakback pipe."

This info originates directly from the manufacturer, Bosch.