Ok I have a 1986 rx7 N/A, it starts up okay but it doesn't want to idle and backfires every 20-30 seconds. The car has compression, but I noticed that I don't have one hose or vacumn line. I realized this when I saw ambassador_josh's picture from one of his earlier posts.



The hose that I am missing is highlighted in Red. Thank to ambassador_josh I can now maybe get a chance to solve this problem. I just wanted to know what the metal pipe is for and what does it do. The rubber hose that comes from the air filter is routed somewhere below the intake manifold in my car, but in the picture it is routed to that metal hose.

That is where the BAC valve pulls air from. The rubber hose on the near side of the metal line should go to the large plastic pipe coming from the AFM. As far as I know, this has to be hooked up for the engine to run well.

what is a BAC valve and where does it go

The BAC valve is on the drivers side of the uppermost section of the intake mani, i think its called the plenum. It allows extra air into the engine to compensate for higher load from the alt or AC etc. There is also a solenoid below the bac mounted on a bracket that I think is for the AWS. The metal line feeds this as well. I will try to find a pic of these two things. Hope this helps



Andy

Hey Rahim, this is what you're looking for. It's circled in white. You need this. Mine's bad, because anytime I turn on an accessory during idle, the idle drops.

BTW, anyone got any ideas on how i could clean up that TB? I realized as I snapped pics of my car, the fuckers filthy.

Wirewheel, maybe?



Another angle on the BAC. Also shows the other solenoid fed by the hardline.

I would remove it, protect the tps, brake clean the shat out of it, finesse it some with some scotchbrite, then you could do any number of things; polish, paint and clear, or just put the clean part back on.

First off I just wanted to thank all you guys for the help.

Second I wanted to tell ambassador_josh that I have that unit but I don't have the metal line that feed the Bac and AWS, but thank you very much for the pics od the parts.

Ok I just went outside to check my rx-7 and the hose( highlighted in red) that should goes from the AWS solenoid to the metal pipe is actually going to intake. ( the hose highlighted in blue.



Now to make the problem easier to understand. The hose that is highlighted in red is running to the intake that is highlighted in blue.



And the Bac valve that I have, has only one hose and not two like the one in the picture.

The AWS solenoid is just a valve so as long as the hoses arent leaking, they should be fine. The BAC valve has only one air hose going to it, the other two hoses are coolant lines going to the thermowax, so counting the aluminum block screwed on to the BAC, there should be three hoses, one for intake air, and two for coolant.



Check the for-sale section for the metal line, someone is bound to have one. Ill check around here too.

I'd like to donate this hefty kick in the balls to the mazda engineers who made this overly complicated.

Many people are quick to blame the Mazda engineers. Guess what? The engineers had to design cars to meet our smog requirements. That’s “our” as in you and me. How did it get to be “you and me”? We elect officials who decide which way the smog winds blow. Those among us who don’t vote? No comment.

BTW, that is the AWS solenoid you guys were referring to. If I remember correctly all that does is make the engine rev up to 3k rpm for the first 17 seconds when the engine is started. If you don't want that to happen you may simply remove it with no ill effects.

I live in OK, with no smog laws https://www.nopistons.com/forums/pub...IR

I hate you.