Hello, I just bought a 1988 Mazda RX-7 Convertable, I love the thing, But the problem is has is the emission, it keeps Failing, at first it was the HC. so I replaced the Spark Plugs, New Spark Plug Wires, brand new Cat Converter, and Oil change and Oil Filter. I used the "Garanteed to pass" as instructed. Went to another place cause the guy who did it last time wanted to fail me because i changed the Check Valve cause the old one was broken, and he didnt accept the Universal one i got from pepboys. So I went to annother Smog test area. and the results came out diffrent, but not so well. I dont know what the Problem is now, or dont know what i can do to fix it. if anyone in here is able to help, i would really appreciate it.


For 15mph /1626rpm:

HC Max 121, Meas 587

CO Max .76, Meas 2.43
//
//
For 25mph/2695rpm:

HC Max 96, Meas 93


CO Max .65, Meas 0.03

 

It sounds like the ECU did go into closed loop when doing the 25mph, and you passed that part.

To me, it sounds like the airpump isn't pumping air to the exhaust ports via the Air Control Valve when at lower speeds (15mph). The airpump, pumps air via the air control valve to the exhaust ports at idle and lower speeds (some other times also).

The airpump pumps air to the exhaust ports (located prior to the 02 sensor FYI), to lean out the mixture coming out of the engine. Usually the mixture coming out of the engine is in the 13 afr range. By mixing air with that exhaust coming out, the end result is a mixture closer to 14.7 afr prior to getting to the catalytic converter. A catalytic converter is at it optimum when the exhaust coming into it is closer to 14.7 afr than say 13.0 afr.

So go to the online FSM for your car and check out the air control valve and the solenoids(relief and switching), that control it. Fuel and Emissions Section.