Digital Fuel Adjustment System
The Digital Fuel Adjustment System by Punk Performance
In this guide we will cover some of the basic details of the DFAS Performance chip or full name Digital Fuel Adjustment System
What will you need?
A multimeter, heat shrink, solder and soldering iron. All available from Punk Performance or your local electronics store.
You will also need an EFI vehicle that uses a Voltage out putting MAF/MAP or hotwire type Air-flow meter.
What types of vehicles will the DFAS suit?
The DFAS will work on all voltage out putting Air-flow meters, Map sensors, Hotwire or Vane types sensors.
As well as being able to intercept the Oxygen sensor signal, it can basically be used to map any volatge signal on the vehicle such as Throttle Position sensor etc.
The DFAS will not work well on frequency type MAP sensor as it is a voltage mapping system.
Overcome boost cuts
Tune and Modify air/fuel for power and economy
Allow air-flow meter or injector swaps
Change closed loop running characteristics
No Laptop required
The Digital Fuel Adjustment System is unlike any other commercially available interceptors
on the market.
It is affordable in cost and very easy to fit and tune. It offers fantastic drivability and it is no exaggeration to say the release of the Digital Fuel Adjustment System (DFAS) is set to revolutionize the electronic performance
industry. With over two years in development by the best electronic minds in the world, numerous of prototypes and hundreds of hours spent testing and tuning on an enormous variety of vehicles, The DFAS is immense with
capabilities! Do not be fooled by its apparent simplicity (four wires to connect). In use the DFAS has left many experts out there speechless after driving a vehicle equipped with the Digital Fuel Adjustment System!
The DFAS can be used in a number of different ways- more commonly it is used to intercept the Air-flow meters signal. In many vehicles, the air/fuel ratios are not set for maximum power. Normally the manufacture sets up the vehicle to run very rich mixtures at high loads to provide a measure of safety if the car is held at a sustained full throttle for an hour or two. So instead of an air/fuel ratio of (say) 12.5:1 at full throttle/high load, the standard Electronic Control Unit (ECU) will provide a much richer air/fuel ratio of 10.5:1. In most modified cars running the standard electronic management, the air fuel ratios can be even richer! If these mixtures can be leaned out, power will improve. So what does all this have to do with intercepting your air-flow meter? Well the ECU decides how much fuel to inject into the engine primarily on the basis of the airflow meters signal. When the engine is consuming a lot of air, the air-flow meters output voltage will be at the high end of its range. This means that if an air-flow meters output signal varies from 1V at idle to 4V at peak power, the signal output in the 3V to 4V range will need to be changed to lean out high end mixtures. Specifically, to lean out the top end mixtures, these voltages need to be slightly reduced.
The DFAS can make these sorts of tuning changes with ease, reducing or
increasing just those voltages that need to be altered while leaving the
rest of the signal untouched.
Changing Full Load Air/Fuel Ratios
A typical use for DFAS will be to adjust full-load mixtures by modifying the output of the Air-flow meter. In RUN mode, the display can be used to work out which load points need to be changed. For example, at low loads (e.g. Idle), the minimum
load point displayed might be 30. In cruising conditions, the loads points around 50 might be shown, while at wide open throttle at high revs, load points in the 100-120 range might come up on the display. In this case, it’s the latter area where changes will need to be made. In other words, if you have an assistant watching an Air/Fuel ratio mater and the LCD Controller, It will soon become obvious at which load points changes need to be made. if you have the DFAS connected in Coarse mode, don’t change the output voltage in large steps, as the air/fuel ratio might then dangerously lean. Instead, start off by making small reductions or increases until you get a feel for sensitivity of the system to changes. As described above, keep the voltage changes at adjoining load points smooth so that there’s no sudden jump in values that could cause the engine to stutter. Then it’s simply a case of adjusting the voltage levels up or down at the different load points until the desired
air/fuel ratios are achieved. If it is well-tuned, the DFAS gives absolutely factory drivability- and tuning is very easy.
Overcoming a turbo boost cut
If the vehicle cuts fuel and/or ignition on the basis of the signal received from a MAP sensor or Air-flow meter, the DFAS can be used to limit the sensor’s output voltage so that the ECU never sees a high enough level to trigger the boost cut.
The load point at which the ECU cuts fuel can be read in real time by monitoring the input in RUN mode. The load points above this point can then be reduced just enough so the cut no longer occurs. Note that depending on the vehicle, the air/fuel ratio may also be changed by this process – it’s wise to check the air/fuel ratios before and after implementing this modification.
If larger injectors are fitted, the DFAS can be used to reduce the output of the Air-flow meter so that the correct mixtures are retained. In order that the ECU can still stay working roughly within its normal operating envelope, such an injector change shouldn’t be radical, otherwise idle stability may suffer and the car may also not drive very well. Larger injectors require changed values at all load points which are accessed and this tuning is best carried out on a dyno with a good air/fuel ratio meter.
Changing Air-flow meters
An air-flow meter electronically compatible but slightly lager can be fitted and then the DFAS used to recalibrate its output. As with injector swaps, in order that the ECU stay working roughly within its normal operating envelope, such a change shouldn’t be radical. Again all load points accessed by the engine are going to require mapping and this can be done roughly with a good air fuel ratio meter, but is best achieved on a dynometer.
Changing Oxygen Sensor Signals
The DFAS can be configured for the 0-1V signals commonly outputted by the oxygen sensors. The resolution remains at 128 load points and the tuning calibration at 127 adjustments up or down, giving extremely fine tuning. The DFAS can be used to alter closed loop mixtures (in the same manner as for Air-flow meter signal modification). Although because of the sudden step in the oxygen sensor voltage as mixtures pass through stoichiometric, some experimentation will be needed to get the right results.
Extensive testing on the DFAS on a wide variety of vehicles showed that it has extremely effective tuning control over air/fuel ratios, together with very easy tuning and simply
brilliant drivability it is the best value for money out there.