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Throttle lift off lamda

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When throttle liftoff lamda gets rich and i cant understand why? We are worried that the turbo is getting hot from the an burned fuel. Is this a problem? Can Engine overrun function fix this?

Have attached two pictures.

GPR-DI M142

Attached Files

I would say your engine efficiency table is not tuned in the 35 kPa, 3000-5000 RPM area. If you want to cut off the fuel, you should enable Engine Overrun Mode to disable all injection when the RPMs are high and the throttle is closed.

Hi Jonathan,

As David has suggested, enabling the Engine Overrun Mode will assist by turning off the Fuel Injection in an overrun condition. In the case that you are showing here, I wouldn't be too concerned about heating the turbo as there isn't any load on the engine and the volume of exhaust mass running through the engine and exhaust system will also very low. The extra fuel going through from the excess fuelling will also assist in cooling the system.

The reason that it looks as rich as it does is that you have the throttle closed leading to a small air mass entering the engine, but the fuel injectors are supplying a greater mass of fuel then is needed to hit the Fuel Mixture Aim based off of the Efficiency table. The overall quantity of fuel being delivered is quite low.