My 1998 mazda 626 es 2.5L engine is running rough at idle and acceleration. I just replaced my valve cover gaskets and checked for vacuum leaks. I did run across a blue/yellow strip wire that looks to connect to the engine somewhere and leads back to the PRC solenoid. I have looked all over the Web and repair manual with no answer to where it plugs into on the engine. It looks as though it goes onto a post of sorts as its a round plug for a single wire. Any suggestions?

 

The blue/yellow wire goes to the PRC solenoid (pressure control solenoid valve) Fuel pressure regulator solenoid. According to the wiring diagram. There should be a vacuum hose coming from the fuel pressure regulator to the PRC and another vacuum hose going straight to intake vacuum. It should not set a code for one bank unless there is a vacuum leak on bank 1 intake runner.

 

Thanks, but I was asking about where that wire leads too from the prc solenoid. The wire end that's not connected is the far end from the prc solenoid.

 

The wiring diagram shows it going directly to the PCM. It does not show a connector as you describe. If the PRC was disconnected it would not give the symptoms you describe however.