Easy Wastegate
Easy Wastegate replaces the stock turbocharger model's wastegate control with two position maps you fill in yourself, so the wastegate follows what you ask for instead of what the factory model calculates.
Contents
What it does
On a stock Simos 18 the wastegate position is worked out by the turbocharger model from turbine and compressor data, then trimmed by a position controller. That model is calibrated around the factory turbocharger.
Easy Wastegate takes the position straight from a feedforward map instead. You give the ECU a wastegate position for every combination of engine speed and requested boost, and that is what it drives — which is what makes it usable on hardware the factory model knows nothing about.
SWG
SWG is a similar patch from switchleg. It takes wastegate position out of the stock turbocharger model in the same way, and it can be configured in the simos.app Tune Editor as well.
Whichever of the two you run, the stock turbo model section below applies — its limits stay live and still need raising.
The two maps
Wastegate Position Feedforward VVL 0
Used on the low valve lift profile.
Wastegate Position Feedforward VVL 1
Used on the high valve lift profile.
Used on the low valve lift profile.
Wastegate Position Feedforward VVL 1
Used on the high valve lift profile.
Both maps have to be filled in. The engine switches between the two lift profiles while driving, and a map left at its default will show up as a step change in boost behaviour at the switch point.
For ease of tuning you can make them both the same — put identical values in VVL 0 and VVL 1. That takes the lift switch out of the picture while you dial the boost curve in, and you can split the two maps later if the profiles turn out to need different positions.
Setting up the axes
X axis — engine speed, in rpm. Spread the points across the range your engine actually builds boost in.
Y axis — relative boost pressure, in hPa. Start at 1000 hPa and end slightly above your target boost, so the top row of the map is still inside the range you use.
Y axis — relative boost pressure, in hPa. Start at 1000 hPa and end slightly above your target boost, so the top row of the map is still inside the range you use.
Set the axes before filling in values. Changing an axis afterwards moves every cell it belongs to, and the work has to be redone.
Filling in the maps
The map values are wastegate position: 1 means closed and 0 means open.
As requested boost rises, the wastegate generally needs to close more, so values increase towards the top of the map. Start conservative — more open than you think you need — and work up while logging, rather than starting closed and chasing an overboost.
The stock turbo model no longer applies
Once Easy Wastegate or SWG is in use, wastegate position comes from the feedforward maps and the stock turbocharger model is no longer in the control path.
The compressor model maps no longer describe the turbocharger you have fitted. Under Turbocharger / Model - Compressor these are:
• Turbo Compressor Surge Line
• Turbocharger Compressor Surge Line Hysteresis Part Load
• Turbocharger Speed
• Air Temperature Increase Factor
• Compressor Efficiency
• Turbocharger Compressor Surge Line Hysteresis Part Load
• Turbocharger Speed
• Air Temperature Increase Factor
• Compressor Efficiency
Turbocharger speed and compressor outlet temperature are derived from those maps, so on different hardware the figures the ECU works with are simply wrong. The torque management thresholds that watch them will still intervene and cut boost, so raise them out of the way. Under Turbocharger / Torque Management:
• Turbocharger Speed to Start Torque Management
• Turbocharger Speed for Maximum Torque Management
• Compressor Outlet Temp to Start Torque Management
• Compressor Outlet Temp for Maximum Torque Management
• Turbocharger Speed for Maximum Torque Management
• Compressor Outlet Temp to Start Torque Management
• Compressor Outlet Temp for Maximum Torque Management
Turbo Max Pressure Ratio still applies. Leave it where it is — it remains a real limit, and it is not one of the values to raise.
Raising the four thresholds removes protections that were calibrated around the stock turbocharger. They are raised because the model behind them no longer matches your hardware, not because the underlying limits stopped mattering — the turbocharger still has a speed and a temperature ceiling, and after this nothing in the ECU is watching it for you.
Logging
Wastegate position is logged as a percentage in the simos.app iOS app. Log it together with requested and actual boost while you fill in the maps — it is the only way to see whether a cell is doing what you expected.
Other apps can log the same value by reading RAM address 0xd000f90c.
Flashing the patch
Adding or removing a patch requires a Full Flash. Changing map values afterwards is calibration only, so those go out as a CAL Flash — see CAL Flash and Full Flash.
Driving a pneumatic wastegate through an N75 valve rather than the factory actuator? See the WG N75 patch.