Xantia V6 fuel consumption readout ?

[Mandrake]

Hi all,

I know that no Xantia came with a fuel consumption computer but that several Peugeots with the same engines came with them such that they could be retrofitted to a Xantia.

Does anyone know if the ES9J4 in the V6 supported outputs for a fuel consumption computer and whether that was used in a Peugeot 406 V6 ? If so what does the display look like and would it be hard to retrofit ?

Just thinking pie in the sky again...

[addo]

Do you really want to cry that much?

A D8 406 V6 trip computer should work fine - might be worth looking to see if they have a "1625" in the circuit which is (in earlier cars) an interface between 1620 and the trip computer.

[Chris570]

well it exists on the s2 xm with the es9 engine so the ecu can certainly do it

[Mandrake]

How do these fuel consumption meters work anyway ? Does the engine ECU calculate fuel usage purely on injection times, making the assumption that the injectors are all working fine to known properties and that the fuel pressure is properly regulated ? Or are they a bit smarter ?

(Fuel rail pressure, battery voltage, injector cleanliness all affect quantity of injected fuel for a given injection time - the ECU knows the battery voltage but can only presume the fuel rail pressure and healthy injector function)

[taffy]

http://www.frenchcarforum.co.uk/forum/v ... p?p=165616" onclick="window.open(this.href);return false;
im looking for pauls now

[taffy]

http://www.frenchcarforum.co.uk/forum/v ... =39257&sta" onclick="window.open(this.href);return false;

[xantia_v6]

I fitted one to my last Mk1 V6. The ECU certainly supports it, but there is no wire to the pin on the ECU.
Most of the necessary connections are found on the back of the instrument panel, but the ECU wire needs to be run to the ECU.

I used a 406 D8 display, an XM display would probably work, but the range calculation would be less accurate as the XM has a bigger tank. The 406 display has much faster updates of instantaneous consumption than the XM.

On a mk2 Xantia, you could fit a mk1 indicator switch and use the extra horn button to control the trip computer function.

The fuel consumption is just calculated from injector pulse width, but seems to be surprisingly accurate in most cases.

[addo]

I'd think if you are keeping the same rail pressure and number of cylinders plus injector capacity, it shouldn't lose any accuracy from one car to another.

[xantia_v6]

The ECU takes injector size, flow rate and number of cylinders into account and provides a pulse equivalent to millilitres of fuel used, so the same computer can be used regardless of engine type. The trip computer has the fuel tank size hard-coded for estimating remaining range.

Injector flow rates have to be pretty well matched to get good emissions performance, and fuel consumption is driven by the average, so the trip computer should get more accurate with more cylinders. Rail pressure Relative to manifold is an assumed variable.