I know, this is a complex question, and probably only the engineers who developed the engine can give me a precise answer, but I'll ask anyway:

In AJ33S 4.2 S/C engines (without VVT), does the ECU take into account the amount of recirculated exhaust gas from the EGR valve when calculating the air-fuel mixture?

I mean, the EGR system recirculates exhaust gases into the intake, replacing part of the fresh air. As a result, the amount of oxygen reaching the engine is lower, so the fuel quantity should be adjusted (reduced) to maintain an optimal air-fuel ratio.
Is the Denso ECU capable of compensating for this oxygen reduction caused by the EGR and adjusting the fuel accordingly?
Theoretically, it should be, but I actually hope the system is too outdated to do so. Because if the ECU does account for the EGR, physically bypassing it could be a bad idea, and an electronic intervention might be necessary - which is very difficult and certainly expensive on our cars.

On the other hand, if the EGR system isn't factored in by the ECU, disabling it should be much easier.

I'm open to any ideas!

 

I have a 2002 S-Type R and I blanked off the EGR valve (but not disconnected the valve itself). This means it activates but flows no air. The ECU can detect this and throws on the MIL light, so the ECU does detect the impact of the extra gasses from the EGR and notices when it's not there.

 

"does the ECU take into account the amount of recirculated exhaust gas from the EGR valve when calculating the air-fuel mixture?"

Yes in both the map and with the O2 sensor

 

"blanked off the EGR valve (but not disconnected the valve itself). This means it activates but flows no air. The ECU can detect this and throws on the MIL light, so the ECU does detect the impact of the extra gasses from the EGR and notices when it's not there"

The intake air flow sensor will see a reduction in flow when the EGR opens. Generally, it just compares that to the EGR position sensor map.