My V8 is apparently over fueling, on short distances i am doing 2km per litre, open road 4,5km /l, has anyone installed any aftermarket fuel management systems?

 

1/4 gallon per 1.2 miles. You have bigger problems than engine management. Even when the check engine light is on for a management problem (O2 sensor, MAF issue) its till goes to a set of pre-programmed parameters and you still get decent fuel economy, but its not that bad.

What year is your truck? Is your check engine light on? Have you stayed on top of your services, engine air filters?, how many miles or Km does your truck have? Have you checked to see if you have a hanging caliper?

The company that works with Turner Engineering does ECU flashing for
Economy, Power, etc. That being said, that also depends on your vehicle condition. see link below

http://www.tornadosystems.com/produc...8-thor-engine/
no affiliation btw.

 

5km/L works out to about 11-12 mpg, which is on the low end of normal for highway running. 2km/L is under 5mpg which is atrocious. You have something going on that an ECU flash isn't going to fix.
Try scanning for pending ODB codes to see if any sensors might be malfunctioning.

 

morning, its a 2001 with what i think is 260000 km, but service books were never kept up to date, i bought around 7 months agao and serviced the vehicle right away, also done the heads gaskets 4 months ago because one bank was leaking, power is also low!

 

Your said you did headgaskets 4 months ago. A couple of members have had issues with re-installing older injectors. Could be flooding the motor. The only problem with that theory is if it was flooding the engine, you would know bc it would run horribly....

That being said, you still haven't said if the check engine light is on or if you have any codes.

 

It seams my dash lights are not working, well some of them so I dont know! I am taking it in today to a specialist where they will be checking all the above and see where we come out! I will keep informed once I have an answer, they say the need 3 days>>Thanks