What's it do mister?

pete woods · Post by **pete woods** » 22 Aug 2003, 21:47

96 Xantia 1.9 td
On the injector body nearest the cambelt & between the leak off pipes there appears to be an electrical connection. What is it for?

wheeler · Post by **wheeler** » 22 Aug 2003, 22:27

on the semi electronic control diesels 1 of the injectors has a built in needle lift sensor,its just to let the ECU know when the injector is firing then it can work out the others using the TDC sensor.

pete woods · Post by **pete woods** » 23 Aug 2003, 04:04

Ah ha! Would a fault here effect starting & or lead to a higher tickover speed but otherwise normal running?

wheeler · Post by **wheeler** » 23 Aug 2003, 04:57

i doubt it would cause high tickover,but it could cause bad starting or cutting out,its actually more likely to be a dodgy connector (2pin) than the injector itself,if you think you are having problems with it try cutting out the connector & soldering the wires together (making sure you dont get them round the wrong way)

Dave Burns · Post by **Dave Burns** » 23 Aug 2003, 05:07

The flywheel sensor and the injector lift sensor provide the data required by the ECU for timing adjustment purposes, it can compare the actual point of delivery with the ideal setting in the software for any given engine speed, it can then adjust it accordingly.
Previous to this the injction timing advancement was purely mechanical, the faster the engine went the higher the fuel pressure inside the pump body bacame, this acted on a spring loaded piston that turned the roller ring as it moved.
Most of that system is still in place, but now the varying fuel pressure to operate the timing advance piston is controled by an electronic valve and no longer relies purely on engine speed, which was not ideal.
Any shift in the timing affects all the injectors as a whole, they are not adjusted individualy nor can they be since this is still in the main a mechanical system, the ECU on this engine has no control over any other function of the injection pump.
Unlikely that a fault here will cause bad starting and at the same time normal running once started, and you can disconnect the timing signal at the pump causing it to go to full advance, the engine does not speed up if this is done so that would seem to answer your second queery.
Dave