Why is standard ECU better after being reprogrammed ?
There are many reasons to stay with the standard ECU:
- Specification: The ECU is extremely fast and has a very powerful processor.
- Development: Your car manufacturer invest millions of $$ in software calibration and we all can benefit from this. We only need to work on approximately 3% of the data contained in the ECU. This way we retain all of the difficult and time consuming mapping such as transients, warm up, cold start, overrun.
We can then concentrate on remapping outside the parameters set at the conservative setting issued at the factory. Aftermarket replacement ECU's cannot ever hope to compete with the speed, power and complexity of the standard unit, this is why the ability to re-map in the way we can renders these units and add-on signal modifiers obsolete.
- Functionality: All functions of the standard ECU remain. Features such as diagnostic trouble codes, ECU control of the climate system, vehicle immobiliser and fault code memory. None of these functions are available with replacement programmable ECU's and with the add-on signal modifiers which cut into the vehicle wiring, they can actually add a fault due to the ECU seeing the wrong signals.
- Security: Programming is performed via the diagnostic socket of the car. No hardware or wires are added or removed from the ECU. The standard factory diagnostic unit will report the ECU as being normal and unaltered.
- See the aftermarket ECU comparison for more information.
|Original 'Unisia JECS' ECU||Possum Link ECU||DasTek Unichip|
|ECU Type||Complete ECU||Complete ECU||PiggyBack ECU|
|Fitting||Plug and play. Change in 3 minutes.||Plug and play. Change in 3 minutes||Requires cutting of loom wiring.|
|Appearance||ECU fits car as standard. No signs of modification.||Replacement PCB - board differs in appearance, though fits in the original casing.||Additional cigarette packet sized unit|
|Reprogrammable||Yes, by Subaru or EcuTek dealer.||Yes. With Link handset or laptop software by dealer or owner.||Yes. By Unichip Dealer Only.|
|Compatibility with Subaru Diagnostic Tools||Full compatibility and accuracy||Not Compatible||Compatible, though diagnostic tools will read inaccurate values from the ECU, since the piggyback module modifies the I/O signals of the ECU.|
|Reports diagnostic trouble codes when engine parameters go out of safe limits||Yes||No||Yes|
|Mapping effort required to get good idle, cold start & aircon function||None - ECU does this as standard. Only modify what is required.||Provided with a default map that will start and run the car.||None - Piggyback only modifies what is required, leaving what is already ok intact.|
|Air Flow Metering Method||Mass Air Flow||Density-RPM principle using MAP sensor||Mass Air Flow|
|Closed Loop Lambda Control||Yes||Yes||Yes|
|Closed Loop Knock Correction||Yes||Yes||Yes|
|Charcoal Cannister Purge Control (Emissions)||Yes||Yes||Yes|
|Air-con aware Idle Control||Yes||Yes (including cooling fan)||Yes|
|Fuel and Ignition Map Resolution (RPM x Load)||16x16 (256 zones)||10x20 (200 zones)||17x12 (204 zones)|
|Load Scaling Maps||Yes||Choice of two default maps held within ECU||No|
|RPM Scaling Maps||Yes - RPM Intervals may be individually specified||No - Fixed 500 RPM intervals||No - Fixed 500 RPM intervals|
|Boost Control||Yes. Closed loop control by duty cycle, boost pressure and atmospheric compensation maps.||Yes. Closed loop by algorithm.||Optional Extra, available as an additional module.|
|Boost Map Resolution||8x8 (64 zones), 2 maps||16x1 (16 zones) for target boost values.|
|Wastegate Map Resolution||8x8 (64 zones), 2 maps plus configurable turbo dynamics control||N/A|
|Rev Limit Adjustment||Yes||Yes||No|
|Soft (Smooth) Rev Limiting||Yes||Yes||Yes|
|Speed Limit Adjustment||Yes||Yes||No|