Secondary Injectors not working
 

Hi, new to the Club. I recently bought a 91 RX7 Very non turbo. Secondary injectors not engaging at 3800rpms. Acceleration dulls out completely around 5000rpms in every gear. Replaced ECU and still no changes. Is this a potential fuel pump or filter issue? Is there a solenoid resistor that may need replacing? I'm Stumped. Any suggestions would be appreciated. Thank you.:scratch:

Pull codes.
RX7 FD and Series 5 Error Codes

Likely a grounding issue w/the main engine ground which connects to the ECU grounds.

Have a guy that is going to pull codes for me next week. Great info on the ground. We will start there and work our way around. Thanks.

Ran wire from single green connector to ground on battery. Engine light not flashing. Just turns off. Any suggestions or does that simply mean there are no error codes?

Likely no error codes. If you wanted to test the error checking system then unplug the boost/pressure sensor as an example followed by checking for codes.

The resistor under the air filter box. Is that an injector resistor or fuel pump resistor? Getting conflicting info.

The S5 would not have a resistor box for the injectors (limited to early S4's). The relay you have is fuel related.

Thanks Satch, next step is to take the injectors out themselves and see if the coils are still good. I'll continue to try and get to the bottom of this.

You can add grounds to the grounds at the ECU. You could also unplug the TPS and remove the vacuum hose from the pressure sensor and you can trick the secondary injectors into firing above 3800 rpm w/the car in neutral. You can test the secondary injector wires at the ECU (2 of them) to see if they are pulsing a ground when they are supposed to be working. An LED light connected to a source of voltage and the other wire to one of the secondary injectors ECU pins and w/the engine rpm above 3800 the light should flash/flicker to indicate the ECU is at least doing its job.

Been awhile. But just in case you wanted to know, I finally got to the bottom of the problem! Catalytic converter and exhaust. I took off the CC and she screamed alive. Going to be putting on headers and performance exhaust in the next few weeks. Thanks for all the help!!