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Port Injection MRP Compensation

Practical Dyno Tuning

Discussion and questions related to the course Practical Dyno Tuning


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Hi

Just watched, re watched then watched again the Toyota 86 worked example especially the part where you talk about Manifold Pressure Relative Pressure Compensation.

I am attempting to tune my own Toyota 86 with a Rotrex supercharger strapped to it and am using an RomRaider/Openflash tablet combination.

The top axis is Manifold Pressure (psi relative sea level) with the ratio beneath.

What is the ratio even mean I cant really find anything online what are we trying to compensate. Also I assume i need to make my maximum top axis max boost (9psi gauge) at sea level so 9+14.7=23.7 and then scale it down to max vacuum -28.23 nice and smoothly?

This table is simply a background compensation for the fuel delivery based on manifold pressure. Essentially it's working on the principle that as the air density increases we need to increase the fuel delivery to maintain a consistent AFR. In stock form the ECU is only scaled to atmospheric pressure since the engine is N/A. If you don't modify this table as described you will end up with the engine leaning out as you transition into positive pressure. With the sprintex SC kits we run using the MAF so even though we exceed the maximum reading of the MAP sensor this actually isn't an issue and hence we don't need to scale this table to match our maximum boost. If you're exceeding the flow capability of the MAF and you're switching to SD then you'll need to fit a larger MAP sensor and scale this table accordingly.