What is a AAC valve, F.I.C.D, Air regulartor, Vacuum control

[Guest 79Datsun280zx]

Im upgrading my turbo car and im not sure what to get rid of on the intake and what i need to keep. Im getting a aftermarket BOV so i wont need the stock one. There is a tube that comes out of the air inlet pipe from the turbo going to the throttle. This tube branches into 4 parts. ones goes to a AAC valve, another goes to the air regulator and another goes to a F.I.C.D, and im not sure what the 4th goes to. Could someone please tell me what all these parts do and if i can remove them or not? On the air regulator there is a connections that im guessing goes to the ECU it also appears that coolant is pumped through here. Theres also this Emergency relief valve, when i turn up my boost is this going to be a problem? And there is this Vacuum contorl modulator, its down towards the bottom front of the engine and has two electrical connections and some vacuum connetions. It seems that this CECU controls this part. What does this stuff all do?? Ill make a list

 

1) ACC valve

2) Air regulartor

3) F.I.C.D

4) 4th thing?

5) stock BOV?

6) Water lines through the air regularo and throttle body? what are they for?

7) Emergency relief valve

8 ) Vacuum control modulator

9) CECU

10) Vacuum control valve

 

I posted on another site and all i got was "go buy a CD manuel" $70?! no way. I have a hanes and read through it from front to back almost. I know all the names of things now and can look at the diagrams but dont know exactly what they do and what ill need to get ride of, modify and keep to run my motor after i add all my mods (t3/t3, intercooler, aftermarket BOV and piping, 60mm throttle body. Is there anyone willing to actually help me here?

 

THANKS!!!

[zxgts-4]

What can we say.

Looking at the schematic on page 106 there is no FICD on turbo and the manual tells you what all the components are for, as to what can be removed probably not much. Probably better to ask how someone else fitted similar after market items that you have or have a professional fit them. Neil

[Guest 79Datsun280zx]

Your right there is no F.I.C.D on 106. But if you turn to page 67 and look at the turbo external components diagram you will see it. Its located on the intake right by the AAC valve. Yes the manul does explain some stuff but not everthing like the FICD. Or the vacuum control valve that you see on page 67 also. But thats a good idea. Whos a good person to ask how they set theres up? Im not trying to get rid of stuff, i just want to know whats going to work properly with increased boost and my after market BOV and piping and whats going to have to be modified or removed. Like is the ACC valve the stock BOV? Anyway, who can i ask for info and pictures?

[mobythevan]

not trying to beat you up, but there is no BOV(blow off valve) on the stock turbo. The is a pop off valve which is the safety valve to protect overboosting if the wastegate on the turbo malfunctions. If the wastegate is working correctly then it controls boost, but if carbon builds up the or the vacuum pod fails then the wastegate may stay closed and build too much boost, that is where the pop off valve is a backup. Starting from the back of the intake near the firewall you have the EGR valve, then you have the pop off valve (it has 1inch pipe threads into the intake manifold). IF you are going to add a boost controller and raise your boost then you need to modify the pop off valve or plug the hole, otherwise it will open around 9-10psi IIRC. The FICD or HICD is what I thought my manual said, this raises vacuum when the AC is turned on. IF you don't have AC then you can plug it. The air regulator lets extra air in for cold start idle. As the engine warms up this closes. You'll always want that to get the idle decent. I don't know exactly how the AAC works?????? But the ECU controls it through the VCM (vacuum modulator). Good Luck.

[Guest 79Datsun280zx]

Thanks! thats the most helpful info any one has given me yet. Dont worry about beating up on me, thats why im asking questions. I wasnt sure if there was a BOV or not. What really bugs me is when people flame me for asking questions like that but dont give me and answer! Anyway i was pretty sure what that relief valve was for, thanks for confirming it for me. I read up on the Air regulator so im quite framiler with that now. The F.I.C.D i had no idea about so thanks! I double checked, it does say FICD...could we be talking about a different part? Its on page 67 of the hanes and its right next the the ACC valve. So now i have pretty much figured out everything except the ACC valve and the Vacuum control valve, both on page 67. I thought that it was a type of BOV, because usually stock BOV's just route the air back into the intake, which is appears that this ACC (axilary air control) does. If its not a BOV then what on earth does this thing do?

[Ben]

As previously stated - the Fast Idle Compensating Device (FICD) will bump up your idle speed when the A/C is on, there is no stock BOV & the Relief Valve is also explained in a previous post. So, I will answer some of the remaining questions:

 

The Auxillary Air Control Valve (AAC) is a vacuum motor in the manifold that is attached to a throttle plate bypass. This device is what gives you a high idle after startup. It is controlled (pulsed) by the Vacuum Control Modulator (VCM). The VCM also controls the opening of your EGR system at the correct load/rpm point.

 

The Air Regulator is a much cruder electric & water heated bypass valve that also influences cold start running speeds.

 

The water lines through the throttle body are there to prevent the throttle plate freezing open (not pretty). If you live in a warm climate, and don't drive the car in cold (not necessarily freezing) conditions then you can probably bypass it.

[Guest 79Datsun280zx]

Thats great information thanks! Now i kinda know whats going on Now that i know what everthing does i think i can complete my rebuild and mods without trouble Since im not going to put my AC back in can i just use that port for my boost gauge and BOV? Or should the boost gauge be closer to the turbo? lol iv had the throttle stick! No its not good, the funny thing was is i blew by some cops when it got jamed i was already doing 60 and hit about 90 before i got it in my head to shut the car off. They must have been pretty busy with the guy they pulled over cuz they didnt come after me. I found that the carpet had gotten jammed in the peddle.

[turbobluestreak]

I removed me, AAC, FICD,Air Regualor, EGR, POP off valve. And my car starts up on first crank in 25 degree weather. But then again I was running 84 ECCS instead of 81.

 

 

 

 

 

tbs

[Guest 79Datsun280zx]

Well i had no idea whether i should be worried about them or not, doesnt the ECU control the air regulator? Wouldnt the ECU be getting bad readings if it wasnt hooked up to anything? Can you send me pictures of your set up? Are you talking 25 degrees C or F? And wont i fail aircare/smog if i start pulling things the the EGR off?