Last post on May 17, 2008 at 4:35 AM
You are in the Volvo XC90
What is this discussion about?
Volvo XC90, SUV
#4 of 6 RE: ECU Upgrade [kylechoffman]
May 16, 2008 (3:15 pm)
What year and engine is your XC90 that is getting only 15.5 mpg?
Over the first 10,000 miles my wife's 2007 XC90 3.2 has averaged 18.8 mpgUS using the pump volumes and trip odo readings (10,328 miles / 550.1 galUS), but we have had individual fillups as low as 13.0 mpg and 15.5 mpg.
The computer in her XC90 consistently gives an mpg value ~4.0% higher than the pump volumes. (So if the true value from pump volumes would be 20.0 mpg, the computer would give 20.8 mpg.) It is possible that in other examples the error could be the other way.
So "third parties" are downloading engine management programs into the ECUs of Volvos? Is this an official Volvo download? How does this work?
#6 of 6 RE: ECU Upgrade [kylechoffman]
May 17, 2008 (4:35 am)
Basic scientific and engineering principles assure that performance tuning of turbocharged engines can increase max available torque and power, but increasing efficiency (higher mpg) is an altogether different matter. I do not think that one can reasonably expect higher mpg after performance tuning.
The IPD site makes no claims about improved efficiency.
The other site states
[Q.] What about the fuel consumption after PPC tuning?
[A.] This depends on your driving habits. If you are using the extra power from the PPC upgrade you will use a lot more gas. If you are making more power you are going to be using more fuel. But during normal cruising fuel economy will usually be the same as stock or even improved. Optimized software in the ECU means that you will get more power and less fuel consumption in general.
There are two ways that mpg could be improved
(1) Improving the inherent efficiency of the engine, the so called brake specific fuel consumption or BSFC. There is no reason to think that performance tuning could do this.
(2) Change the fuel delivery program so that at lower power demand (i.e. light accelerator pressure) the tuner program delivers less fuel than the stock program, i.e. leans out the fuel-air mixture. This might have harmful consequences for the engine, such as higher exhaust gas temperatures.
Do these tuner manufacturers suggest that the highest octane fuel be used with their ECU programs?