Fit a fuel computer?

[GsiCav2000]

what is a fuel computer? what doe's it do? and can you put one into a 93 1.6 8v engine? thanks

[Envoy CDX]

Fuel computer measures the rate of fuel / speed / miles and works out your mpg or general fuel consumption. They can be fitted to most engines but generally require reprogramming.

[GsiCav2000]

will i need one from an other 8valve or will a gsi 16v work aswell?

[vauxtillidie]

you should get one from the same engine for it to be accurate but any will work just the readings will be out, also you may not be wired up for it pull out the clock and see if theres a yellow plug behind this is for the fuel computer this may be taped up to the loom elsewhere behind the glovebox maybe

[Robsey]

Ideally you should get one from an 8V engine without 4x4.

there are indeed 3 types of white memory module that is fitted in the back of the computer housing.

These are for: -
8 valve
16 valve and
4x4 vehicles.

As said above, it would need the memory re-programming to suit your engine, fuel system, wheel size and instrument (analogue needles or digital display) characteristics.

This used to be done by Tech 1 at Vauxhall...the predecessor to the current Tech 2 progamming system.

Will cost approx £60 + vat for a Tech 2 programming session from your dealer.

However if you live in the south east, there is a chap called IanT who will reprogram the module, but only at the club meets in the south east area.
He charges approx £20 for this.

[Mort]

Link to Ian Tills site http://www.abs-zero.com/Vauxhall_computers.htm

A trip computer from any Cav / Calibra can be fitted to your Cav (I believe that the Carlton / Senetor ones have different surrounds so I would avoid them), the memory module is removable from the computer and can be reprogrammed for your engine.

A few things to note :-

Finding the yellow plug in the dash is the most important first step, can be a bugger to find, but there was one in my '95 LS Cav. I found it after the glove box out so that I could have a proper look around.

If you are buying the fuel computer, make sure that you buy the switch that goes with it. These seem to be a lot rarer than the computers on ebay, and have been for some time.

Check the white connector block between the gear stick and handbreak to see if you have the loom for the switch (there should be wires comming out of the drivers side with nothing plugged into them). If it isn't there get the loom from your local scrappies and splice it in at the kerb side of the passenger footwell.

From there, it's all plug and play (other than drilling out the coin holder to fit the switch). All the diagrams that you need to do the wiring are on the various forums, but I can't find them at the moment. Search around and you'll spot them.


I did this to my Cav, one of the simplest and most fun mods you can do.

[Envoy CDX]

As Robsey said, if you have an 8v engine get a fuel computer from an 8v cav / calbra.
Everything I've read states you can't write a 16v chip with 8v data and vice versa (don't know why) But even Vauxhall have different part numbers for the chips.

However, what carlton FC's are good for are the 8v fuel computers simply swap the chip over to a 16v cav fc and bobs your uncle (assuming you get it reprogrammed for the right gear ratio and rolling radius).

[Gaz]

Picture of under the handbrake cover.

If your wired for a trip computer it will have a plug in the far right where this one is empty

[humbucker]

i have a v6 cavalier and the trip computer requires a convertor to register the correct readings (6 cylinders instead of 4) although as luck would have it i bought a 3.0 senator trip computer by mistake so it might work anyway?! will have to plug it in and see.

as for the fascia being different on different model trip computers, you can remove one, say from the carlton/senator, and replace it with the one off of your cav. the fuel computer unit itself is the same size across all models.

[Envoy CDX]

only if its a v6 senetor Dan. V6 computers are found mainly in Calibra's that I've noticed.

[Robsey]

It will probably work, but if it does...

It will need the memory module reprogramming to the parameters of your car, rather than the V6 Senator

Vauxhall Tech 1 job I believe

[humbucker]

ah thanks for the heads up. as luck would have it i think i've managed to get hold of a trip computer already calibrated for a v6 cav / cally so the senator one can be used as a spare. i'll be able to run the 'proper' one and then test the senator one to see how 'out' it is...