1990 GXL

Surging idle are 400-900. Went to smog station and they could not time it because of the idle, so it failed. tried adjusting the Air Adjust Screw but when i jumper the initial coupler, it just idle even lower and does the same surge/bounce. Also, when i adjust the Air Adjust Screw it does nothing. Neither raises nor lowers the idle. Call Mazda and got a APPT. next week but is there anything I could do? my questions...

1. Why does't the Air Adjust Screw Do anything when i turn it.

2. Counter Clockwise = let's air in? Clockwise= Stops air coming in?

3. Could this be the TPS? don't want to touch something that might not even be the problem

4. Can anyone link me to a FULL write up? I be searching but the thread always gets derailed into something else with bits of info on each thread.

thanks for the read.

 

have you checked (and i mean thoroughly) for vacuum leaks? that should be first on the list.

when you're you don't have a leak, check other stuff. have a look at this link: https://www.rx7club.com/2nd-gen-arch...oblems-334730/

 

(Edit: I accidentally commented this on your post instead of mine, probably mis clicked a related post, but I hope this helps.)

Hey! I had the same issue. For context I had all my emissions and BAC and solenoids removed when I bought the car. I tried everything, vac leak testing, tweaking idle speed and mixture. It got to the point where I checked timing and realized that it had messed up timing by several degrees. After fixing this, the car idled better but 500-600 rpm. I of course tried the idle air screw (initial set coupler jumpered) but after a certain amount of turns it would be 600 rpm at the absolute highest with no sort of change even though you'd hear more air.

I had a bunch of advice here on this forum and from others. And I conclude that THE fix was the BAC valve. I got one from a friend, connected it up, started up. Idled a little high, brought it down with idle air screw, now butter smooth 750 rpm. I couldn't be happier. It makes sense now that when you have a lot of emissions and such removed, there is not enough air at idle even with the screw full out. Adding the BAC seemingly gave just enough air for this now to be fixed!