I'm talking about the sensor that bolts to the bracket that holds up the dynamic chamber on S4 NA (BAC side). I think its the intake air temp sensor and connects to the metal pipe going back to the intake pipe (BAC is also connected to this pipe). Its one of the few things I kept after doing emissions elim. I thought the ECU needed this sensor along with MAF and O2 to determine fuel? If I don't need it, great.

You're going to want to keep it, try running with it unplugged see how that works..

it should run ok without it, but you really do want it in there. its the same one for all the fc's, mpv, etc. n326-18-845?



mike

Ok, so Revvin, how do you guys have it hooked up on BigT's car? I don't see the tube in his pic but I can't tell.

I have a sneaking suspicion you are talking about the AWS solenoid, not the IAT sensor.



If it has a tube going to it, it's either the BACV or the AWS, at least if the tube is used for the transmission of air and is anywhere near the throttle body.

There is a long metal vacuum pipe that goes along back of DC next to BAC coolant line on S4 NA in stock form. This metal pipe connects to the underside of the rubber intake pipe and at the other end connects to the BACV and this sensor I'm talking about... I thought AWS was near the throttle body?

There is a long metal vacuum pipe that goes along back of DC next to BAC coolant line on S4 NA in stock form. This metal pipe connects to the underside of the rubber intake pipe and at the other end connects to the BACV and this sensor I'm talking about... I thought AWS was near the throttle body? [/quote]

The thing you are referring to is the AWS. It's a drum looking thing that connects to the tube you refer too, it uses this tube as a source of air so it can make the idle high @ cold start. The BACV also uses this tube for an air source.



The thing on the throttle body related to accelerated warmup BS is the thermowax, which mechanically opens the throttle @ cold start until it's wax is melted, this is the thing that gets coolant flowing through it. It also doubles as a vacuum solenoid for the double throttle vacuum actuator so the double throttle is closed until the thermowax melts if I remember correctly.



99% sure you're talking about the AWS solenoid https://www.nopistons.com/forums/pub...#>/biggrin.png Thats the fucker responsible for the high idle you can disable by starting in gear, it's the only electronically controlled part of that high idle @ cold start system. Why they didn't just use a BACV that can meet the demands of all this stuff and eliminate all the redundant junk, I don't know.... yay mazda.

So I can take out that nasty ****** metal tube? Where is the IATS then??

see the green wire in your picture going to a small white connector, the little thing that plugs into is the IAT sensor, this of course depends on wether my memory serves me right or not. Actually, holdon imma go in the garage and double check on this engine we pulled.



yep, thats it. It's a two wires connector, one of the wires is that green one, it's nestled in there threaded into the drivers side face of the dynamic chamber.





You see the black hose coming down off the hard tube you're saying runs along the back of the dynamic chamber? That hose leads up to the AWS. You can remove it if you want, it might make starting in winter a bit difficult without assistance via pedal though.

btw, nice clean engine bay https://www.nopistons.com/forums/pub...IR#>/bigok.gif

Yes you can remove those if you want, just have to raise you idle to around 1000rpms to compesnate for the electrical loads w/o the Bac.

The air intake temp sensor is right below the bac, little 2 prong connector attached to the sensor..

Cool, thanks! I was thinking after I posted the pic that the little sensor in the DC is NOT the thing I was talking about with the tube connected to it.. jesus https://www.nopistons.com/forums/pub...#>/biggrin.png

If you remove the AWS, but not the BAC, and just route that airtube right to the BAC, it should't affect your idle, right? Just wouldn't get the rev when you start up?



Trying to keep this all straight https://www.nopistons.com/forums/pub...#>/biggrin.png

The AWS controls the 3000rpm rev at startup, then drops it to 1500rpm. The thermowax controls the slow 1500-800 rpm drop as it warms up.

If you remove the thermowax and AWS, leaving the BAC installed, you will get startup at low idle, and it will stay there all the time, right? Let it idle for a minute, then drive sanely for a few, and you're fine?



My idle is so goofy right now, I'm in the mood to do anything that will give me a constant idle that I can tweak https://www.nopistons.com/forums/pub...1047683358.gif

You won't need to raise your idle if you keep the bac, fc maniac wants to get rid of the little pipe back there..

Yeah, the car already idles at 750 right from start up since TB mod so I only want to keep the BAC and remove that AWS and metal pipe. I'd remove the BAC too but I do get some idle/voltage drop issues as it is when I turn on the headlights.

thats because of the underdrive pulleys.

One more thing on this.. I'm ripping out the AWS solenoid and that metal tube and capping the intake pipe nipple. What about the BAC? Doesn't it need that vacuum pipe to function right? All I want to keep now is the BAC.

You really hate that tube don't you? https://www.nopistons.com/forums/pub...#>/biggrin.png

I guess you could run a long rubber line from the intake all the way to the BAC, but it'll be cleaner with that pipe...but yes, the BAC needs that intake air to function (it's not vacuum). From what I understand, it's a solinoid valve that adds more or loess extra air into the intake based on the modulation to stabilize the idle. The electric part controls the idle, but you need that extra air to compensate, since it doesn't control the TB (basically, you could run the entire car with no TB, and a giant BAC)

the bac takes metered air from in front of the tb to after it. if you dont use the tube it will be a big vacuum leak



mike

screw it then, I'll deal with the tube! https://www.nopistons.com/forums/pub...#>/biggrin.png