Can anyone help?? I have a 1987 RX7 with auto. When I turn on the A/C the rpm's drop. If I'm at a stop light the engine dies. I have a shop manual and cannot find anything about this. It seems to me that the BAC valve has something to do with raising the rpm's. Is that so??
Or is it a function of the cpu?? If anyone knows anything about this, please respond - it is really hot here (Las Vegas) !!!!

 

Yes that's true. Most likely your BAC is bad...

 

Try removing the BAC valve and cleaning it. Test the resistance also. If its out of spec replace it.

 

Lastly check the TPS (throttle position sensor) to verify it's working / calibrated correctly.

Have a good rotary mechanic do this if you're not sure. DO NOT!!!! take this to the mazda dealership.

 

I had the opposite problem before the TB mod. A/C off, idle was 200 rpm. A/C on, idle was perfect at 750 RPM. Damn overacheiving BAC! Pull off the BAC and use a can of brake cleaner all in it until the fluid comes out clean. Good luck!!

 

Read this article: http://www.teamfc3s.org/info/articles/idle.html

Read the part about the bac. This article, as far as the bac goes, is not dependent upon whether you have a NA or a Turbo.

One of two things is probable. One is that your bac signal is missing from the ECU. And the second most popular is that the idle of your car is not set correct. Go for the first and read the article at: http://www.teamfc3s.org/info/articles/idle.html

 

Well, the a/c does take a significant amount of power when it's turned on. You need to add a little more extra gas than you do with it off. I have the same problem - but adding more throttle (just a tad) really does wonders. There could be a problem, to my knowledge, I just think it's because the a/c eats up a bit of power, which is why most heavy duty modders here have taken their a/c out, etc....

 

Well of course A/C uses some extra hp.,that's why the BAC is supposed to open some when your A/C is turned on.If everything is set up and working you should see a 50-100rpm increase when you turn on your A/C.Follow Hailer's advice.

 

You shouldn’t need to, the ECU should instruct the BAC valve to do this for you. My engine has a smooth 750rpm idle; with the A/C, headlights, rear demister, interior fan, and windscreen wipers on it sits at 800rpm. The engine sounds loaded (coz it is!) but it’s still smooth.

 

my engine idles at 1200 no matter how much I try to udjust it doesnt change plus I've already set the TPS when I turn the A\C on it idles down to 750 800