MZR DISI 2.3l Turbo Load Targeting Logic Explained

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Steve @ VersaTune
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MZR DISI 2.3l Turbo Load Targeting Logic Explained

Post by Steve @ VersaTune »

Over the years, I've answered quite a few questions on how exactly the Mazda MZR DISI 2.3l Turbo load targeting logic works. So, I thought I'd take some time to put together a clear diagram showing the load targeting logic. For those used to simpler but less consistent boost targeting, this may be helpful when converting to a load based tune.

The process starts with the accelerator pedal position (APP) input. APP and the current gear are the only input that the driver controls. The ECU looks at RPM, current gear, boost air temperature (BAT), and barometer (Baro) and does table lookups to find load limits for each input. It then compares all of the limits against the requested load from the APP requested load lookup table and returns the lowest value of them all.

Next, the ECU applies load reduction if necessary to prevent overboosting when shifting up or down. The inputs for this lookup are current RPM, previous RPM, and current gear. The output of this lookup is a multiplier value. The multiplier is applied to the initial requested load output from the previous step resulting in a new requested load value.

Next, the ECU looks at the current injector duty cycle (IDC), operating load, and mass airflow sensor (MAF) volts. If any of these values are above allowed limits, the ECU reduces the requested load until they are below the limit. The output of this process is the requested load that is sent to the boost control solenoid duty cycle (BCS DC) calculation code.

That same requested load value is then sent to an air density compensation calculation. This calculation looks at inlet air temperature (IAT) and baro to adjust the requested load for the drive by wire (DBW) throttle table lookup.

These various compensation calculations after the initial requested load lookup explain why you sometimes see BCS DC and DBW values in your logs that are different from what you expect based on the APP input.

The diagram below should help :)


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mituc
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Re: MZR DISI 2.3l Turbo Load Targeting Logic Explained

Post by mituc »

Awesome diagram! Can you waste two more hours of your precious time and post a similar diagram for how the timing works? It would be helpful for a lot of people who do not understand why they don't reach certain timing values and then run into knock problems...
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
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Re: MZR DISI 2.3l Turbo Load Targeting Logic Explained

Post by Project_cx7 »

Can you repost the diagram?
2007 Mazda CX-7. Manley H-beam rods, Wiseco 88 mm pistons, King racing bearings, balance the crankshaft, bosch 3 bar map sensor, removed VTCS and egr, JB OCC, JB 3.5 inch intake, FMIC, Forge v1 BPV, BNR S3 turbo, 3 inch catless DP.
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Ugnius @ VersaTune
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Re: MZR DISI 2.3l Turbo Load Targeting Logic Explained

Post by Ugnius @ VersaTune »

Sorry, some files got deleted during the website upgrade. Should be fixed now.
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