Ok I was looking in my service manuals and its talking about for the S4 non turbo that the ECU reads a mileage switch that after 20k miles it turns on? What is this for? What does this do?

 

I've never actually looked into it, but I'm assuming it's to void your federal ECU warranty. There is supposed to be a 5 year, xxx mile warranty on your emmission components.

 

No, after twenty thousand miles it turn OFF. One thing it effects is the Port Air Solenoid on the ACV. That valve is turned ON for the first twenty thousand miles. It ports a small amount of airpump air into the.......exaust ports, anytime the engine is running...til twenty thousand miles. It's an emission thing. There might be other things that are effected under twenty thousand miles, but they are not transparent when looking at the fsm.

Oh....it gets energized again at one hundred thousand miles and turns off at one hundred twenty thousand miles. Part of a poor design I suppose OR someone thought that the RX-7 would never make a hundred thousand miles (humor).

NOTE: Don't mistake a voltage drop for signs of something not being powered up. Been there, done that myself. The showing of 12v after twenty thousand miles is a sign that the ECU is no more putting a ground on the solenoid, therefore no voltage drop down below say 1.5 volts.

 

Very good Hailers

I say we get the word out to the rx community that the port air solenoid needs to be disconnected (taking the connector apart out on the engine, then tie-wrapping the ends up out of the way would be an easy way) BEFORE the car hits its next "100,000" mile increment. It does far more harm than good at this point in the car's life, as evidenced by all the "meltdowns" going on at that solenoid. Burning wiring, arcs & sparks, and blown fuses (and ECUs) are not good

 

is this only an S4 thing or is it an S5 thing too?