VR V8 Calais Fuel Inst not working??

[dropthaclutch]

Hi there, I have recently purchased a VR V8 calais and the fuel inst, fuel usage and dist to empty functions in the trip computer don't seem to be working. With any amount of fuel in the tank the dist to empty reads about 1100kms but that's wishful thinking! Also the fuel usage reads 0.18 ish l/100kms which is also not very v8 like and is definitely using more fuel than that.

Just wondering what controls this, I'm guessing it is a sensor somewhere maybe on the fuel rail to tell you how much fuel you are using?? No idea really, just a guess.

I have a friend with a vn v8 calais and his trip functions work fine so if anyone knows where the sensor is please let me know and I can swap parts from his car to mine until it works again and then I can visit the wreckers for the faulty part knowing it's going to solve the problem. Just need to know where to start!!

Cheers in advance.

[The1]

have you checked cals? it should be 625, hold set on each function

[scvs6]

Has the car been converted to gas? Because with my VS, if it's been running on gas for 100kms and not petrol then the fuel usage goes down and dist until empty goes up. Because the computer doesn't realise the car is running on lpg.

[dropthaclutch]

Yea I have checked the calibration, everything is set correctly. No it doesn't run on LPG and never has. Any other ideas anyone?

[88GreenVN]

Run the cluster in Diag mode see if it says "error" in the main screen. Should scrol though 3 screens - the last lights up all segments..

[dropthaclutch]

Yea I have done that as well, everything works fine, all lights light up, just the fuel consumption numbers hardly change. Fuel used ranges from 0.18 - 0.23 ish and fuel inst is at 0 always and dist to empty will range from about 680 - 1100kms or so no matter how much gas is in the tank. Don't think it is a problem with the trip computer itself but I could be wrong. Cheers.

[88GreenVN]

Yea I have done that as well, everything works fine, all lights light up, just the fuel consumption numbers hardly change. Fuel used ranges from 0.18 - 0.23 ish and fuel inst is at 0 always and dist to empty will range from about 680 - 1100kms or so no matter how much gas is in the tank. Don't think it is a problem with the trip computer itself but I could be wrong. Cheers.

It most probably will be 1 of 3 things. 1) the continuity between the ECU and cluster including the cluster PCB and connectors (yellow black wire). 2) fulty trip compter in the cluster. 3) faulty ECO or memcal/tune.

Fitting a test cluster is one thing to try. You could also try a replacement ECU/memcal.

[dropthaclutch]

Ok cheers, will have to look into it. So is it the trip computer that controls the readouts? how/where does it get a signal to say how much fuel is being used etc? Or is it all to do with calibration in the computer that changes fuel used readouts with how many revs the engine is doing and the levels read from the 02 sensor in the exhaust? Really curious to find out how this system works, Cheers.

[The1]

there's base rate calcs in the memcal then injector timing would help calculate your fuel readings.

[aceventura]

The trip computer gets the information directly from the ECU. You manipulate what the trip computer reads out by changing the calibration numbers - It has no influence on what is going on under the hood.

[Cheap6]

Yep, ^ and ^^. The trip computer integrates (in the mathematical sense i.e. sums) the time that the injectors are opened for. With values for the fuel flow rate of the injectors: opening time X flow rate equals fuel consumed. With the input from the speed sensor then the fuel consumption rate per distance travelled can be calculated.

[dropthaclutch]

That all makes sense cheers for that!