Can anyone tell me how to determine if the Idle Air Control Valve is working. In the manual on page f134 it states to disconnect the connector and rev the car to 4K then release throttle and verify the engine speed decrease roughly at 1500-1000rpm. What the hell does that mean? That the idle will decrease to those levels or is there something missing from the text? This is the antiafterburn control and I am trying to stop my car from backfiring when I decelerate. Does this valve even have a connection to the PFC

 

It is controled by the PFC if the PFC is programed to use it .If you have alot of modifications the PFC will not learn to control it . Pull the unit off and clean it , then put some current to the connections and see if the plunger mooves back and forth . The PFC has several settings for idle speed , no load ,electric load and air cond load .The pfc needs to learn each one ,see the PFC instrutions .

 

what you are describing sounds like the ISC. Are these two items the same? In the manual for the 93 they call it the ISC but in the 94 they call it the idle air control valve. I know my ISC is working as it adjusts my idle for lights, defroster, etc. Reading the manual I was under the impresion this valve is something else and is used to prevent afterburn.

 

I do not Know I have the 93 book but I will have to check the 94 book if I can find it .I will look asap .

 

iac isc same. aws is a diff animal.

 

Easy way to check is to turn on the lights to see if the idle raises. You can also change the idle speed in the settings menu. Just be careful not to change anything else if you are not familiar with pfc tuning. Also, some people cut connectors off the harness when removing emissions or sequential turbo control parts. The iac shares a power wire with the grey solenoid connector. Stupid Mazda ran the power to the solenoid, then back to the iac. If you cut that connector it will not work and must be rewired.The iac often gets gummed up because the pcv system dumps into the intake manifold nearby. You can take it off and clean it like David suggested, or swap in a known good one. With heavy mods of big enough ports the idle control works poorly.

 

If you want to try a used one i have one for sale. Worked perfectly fine on my car.

 

While all of the idle controls should be working properly, it seems to me what you are really looking for is to see if your dashpot is working properly (it is the thing that controls your engine returning "slowly" to idle such that you don't backfire). It is completely manual, no electronics involved. I forget the specs, but basically your throttle linkage should hit the dashpot at around 2500 rpm and slowly back it down to idle. I'm sure the specs are in the manual.