ProScan is a combination of software and
hardware that transforms any modern laptop or PC into a powerful, yet
easy-to-use, OBD-II
analysis tool for all vehicles manufactured since 1996.
ProScan can be used to determine why your
Check Engine light is on, and then you can turn it off, saving yourself an
expensive trip to the dealer! ProScan can be used to monitor real-time
sensor data such as oxygen sensors, fuel trims, mass airflow rate, ignition
timing, and much more. This information proves invaluable when attempting
to tune a vehicle. Additionally, ProScan includes performance analysis
tools that measure track performance and horsepower and torque curves!
The most reliable way to dyno a vehicle is on a
chassis dynamometer. It can theoretically be estimated fairly
accurately using vehicle weight and acceleration data, but there
are so many variables that reliability is an issue.
The most reliable method within ProScan is to verify your
vehicle's transmission ratio and axle ratio and calculate the
following ratio for the gear you will use in your dyno pulls:
Kilometers Per Hour / Engine RPM
You can then input this value into the vehicle manager settings.
The drive ratio calculator will attempt to calculate this value
for you, but if you have an automatic transmission, the
calculator is not as reliable.
As long as you can keep your car in the same gear during the
pull, ProScan can reliably determine vehicle speed (in
kilometers per hour) directly from engine speed (rpm).
You will need to be on level ground. If you are accelerating
downhill, your car will accelerate quicker and ProScan will
think your car has more power than it truly does.
You will need to avoid wheelspin. ProScan can not determine when
your vehicle is spinning. If you spin your wheels, ProScan will
think you are going faster than you really are and show a lot
more power.
It is possible to get good results with ProScan's dyno feature,
but with road acceleration, there are a LOT of variables that
come into play. (Drag, wheelspin, slope, etc.) Therefore, you
should always perform your dyno pulls during similar weather and
on the same stretch of road. Don't take the numbers to heart,
but rather compare the results and come to a conclusion.
All acceleration-based dyno tools, including the
popular G-Tech, suffer from the same limitations.
One feature that is frequently requested is a
means of monitoring fuel consumption. I am looking to implement
such a feature in the near future, but the task isn't as simple
as many may think.
The long term and short term fuel trims cannot be used to
calculate fuel consumption. Your vehicle's computer has an
internal table of values that are used to determine how much
fuel should be injected based on other sensor readings. One of
the most important sensors used to determine fueling is the Mass
Air Flow sensor. This sensor tells the computer how much air is
entering the engine. The computer looks at this value along with
other sensor values such as air temperature, engine RPMs, etc
and calculates the estimated fuel required (via lookup table).
Now this is where the fuel trims come into play. Your vehicle
has oxygen sensors in the exhaust which roughly determine the
air/fuel ratio. The O2 sensors provide feedback to the vehicle's
computer and let the computer know how good of a job it is doing
at maintaining a proper air/fuel ratio. If the fueling
information pulled from it's internal table is resulting in a
rich air/fuel ratio (too much gas), it will update the fuel
trims to reduce the amount of fuel requested by the computer.
The actual amount of fuel injected is equal to the amount
recommended in the computer's internal table adjusted by the
short and long term fuel trims.
The long term fuel trim value is based on the average deviation
from ideal air/fuel ratio over a longer time. The short term
fuel trim is based on a much shorter time.
As you can now see, fuel consumption cannot be determined from
the fuel trims, or any other single sensor value. In all
honesty, it can't be calculated accurately using any method,
unless you install a flow meter to your fuel line. However, it
is possible to estimate fuel consumption using calculations
based on multiple sensor readings, and I intend to implement
such a feature in the near future.
Fuel injection is a rather complicated process, but I hope that
this helps you better understand the process. There are many
books and online articles dealing with fuel injection if you are
interested in learning more.
ProScan will still work with
a USB to serial adapter cable. If you need a USB to serial
adapter, you can add one to your ProScan order for a lot cheaper
than you can buy one locally.
