There are a few hardware updates available for the 30-1800 EMS, and AEM would like to ensure that all RX-7 owners are aware that these fixes exist. The following circuits may need to be updated in all existing 30-1800 EMS units:







Throttle Position Sensor

This is a relatively well-known issue among RX-7 users: the RX-7 TPS sends two signals to the EMS, but only one of them is linear from 0-100% throttle. This fix will allow the EMS to work properly without switching wires on the RX-7 harness. Without this fix, the EMS sees the "narrow-range" signal, which should be a constant 4.5V between 40-100% throttle.





Air Conditioning Input

Unlike most other vehicles, the RX-7 doesn't use a simple on/off switch to activate the air conditioning, so this pin needs to be connected to a 0-5V analog input. This fix will allow the EMS to work properly with the factory air conditioning system.





Vehicle Speed Sensor

Although the RX-7 uses a magnetic-type speed sensor, this sensor is not directly connected to the EMS. The EMS receives a hall-effect style signal from the speedometer/gauge cluster. This fix will allow the EMS to detect vehicle speed, which can be useful for datalogging and/or boost control functions.





Check Engine Lamp

The Mazda factory service manual is unclear as to which pin controls the Check Engine Lamp. After some double-checking, we found the correct pin. Like most other outputs on the AEM EMS, the Check Engine Lamp can be configured to illuminate depending on RPM, Engine Load (boost), Throttle Position, Coolant Temperature, Vehicle Speed, and Air/Fuel Ratio (when the EMS is supplied with a proper wideband O2 signal).









If you would like to receive these updates, please call Tech Support at 1-800-423-0046 for more information and instructions.