Quote:
Originally Posted by blackrosenova400
I always wondered, how do those fuel cut defenders lie to the computer without any ill efects?
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On cars like a Toyota Supra or MR2, they have a MAP sensor and a MAF. The MAF is used for primary fueling, ignition timing, load cal, etc. The MAP sensor is just used for stuff like reading boost and checking to see if EGR is working, so devices like the HKS FCD just clamp the max voltage going from the sensor to the ECU at a voltage right below fuel cut would hit. The MAF still reads and adds fueling.
On a car like an SRT that uses the MAP sensor for everything, if you clamp it at say 13psi to avoid hitting 15psi fuel cut, then it will start leaning out when it goes above the clamped voltage/boost level.
On a DSM that only has a MAS for eveything, it will start leaning out above whatever airflow they clamp the signal to the ECU at. It's a hack... Most people used to get around fuel cut on DSMs by putting in too big of injectors and lowering the reported airflow to the ECU via a piggyback like the SAFC. There is no reason you need 550s with a T25, 14B or 16G on your typical pump gas gas, except to be able to fool the ECU away from fuel cut.
So there can be ill effects.