Throttle body mod??? how
 

I've heard of this but i never did it...my car is an NA, does it matter from NA to turbo?? my concern is that i read it removes the BAC for a better idle and improved response and i believe my BAC is clogged causing a rich idle. Can i do the throttle body mod to my '88 FC and if so does it remove the BAC and where can I find instructions.
Also, on a side note, I'd like to organize an FC meet for L.I, NYC and NJ members if anyone is interested. Let me know...heres my site, needs an update.
http://community-2.webtv.net/zxt

the new rims are on the car but pics aren't up yet...also on is the GReddy Front strut brace and awaiting installation is a Corksport (mazdaspeed replica) front spoiler, Pacific side skirts and Apexi Dual N1.
thanks everyone,
Jon
Z-1 Performance

thanks for the site...one more question for ya though ( and i believe someone rcently posted the same)...if I block off the BAC I would assume I just fabricate a backing plate right?? So what happens to sensor on the end?
thanks,
Jon
Z-1 Performance
http://community-2.webtv.net/zxt

Question
 

Hello,
Sorry for jumping in on this. But my BAC valve is shot and I haven't been able to find a cheap replacement yet. I checked out the throttle body mod web site that was mentioned above and was wondering if this would be a legitimate alternative to replacing the BAC valve. Is there any performance/reliability drawbacks to doing this? My car is a daily driver and I do not want to lose any reliability. So far, this mod looks like the cheapest alternative. Thanks for your help.
Vobs :)

I was wondering the same, if there are any drawbacks/gains of getting rid of the BAC valve, since i already did the TB mod.

I may be the least knowledgeable person on this site, but I will pass on what I've read in other posts.
The BAC compensates for the extra load the AC puts on the motor by allowing extra ( unmetered?) air to enter the intake.
I blocked mine of with a plate made from aluminum stock, with a brass barb pressed in where the vaccuum line exits( you can use a BAC gasket as a pattern.) Others have said you can just block it off and tee into the vaccuum line right behind the BAC. If you remove it, you might have to bump your idle up to 1K, when you turn on the AC, idle will drop to 750. Haven't heard anyone say this is a problem.


Hope this helps, BAC is not cheap.

Gregg

as asked earlier, what happens to the sensor on the BAC valve?

do you just unplug it? and does that cause an ecu error code...

removing the BAC is optional with TB mod. I am unsure about the sensor, as I am in the middle of the TB mod myself. I had to stop earlier tonight, cause I need a part and the autoparts stores are closed. I bought some gasket materials, and used the BAC gasket as a tracer, and then used thin aluminium sheet metal with washers to make my blockoff plate.

does the bac really only increase the idle when the ac is on?i thought it was coupled with higher elektrical loads for some reason.but,shit,if thats all it is,mine is comming off![no a/c anymore]
david

Anyone know where I can get to the TB mod instructions now? This link doesnt seem to work;

http://k2rd.freeservers.com/FC3S/TB/tb.html

I am really interested on instructions for stopping the coolant from running through the intake.

Thx

I've moved it...
http://fc3s-pro.com/
Tech...
How-To's...



-Ted

The BAC valve and the TB mod are totally unrelated. There's no need to touch the BAC valve when do the TB mod. If you don't need it and want to tidy up the engine bay a bit, remove it.
The BAC valve seems to only be used for the A/C on S4's, but much more on the S5's. Either way, not having it will affect how the car idle's under load. To test this, just unplug it for a few days and see what happens. Test how your engine idles with the headlights, A/C, rear demeister, etc turned on. Then decide if you need it or not.

BTW, the BAC valve is not a sensor, it's a solenoid valve.

You can run the coolant hose from the rear iron to the BAC valve if you are eliminating the coolant flow to the throttle body. The way I decided to do it is by getting a small metal pipe and clamping the rear iron coolant hose to one side and clamping the BAC valve hose to the other. That way you dont have to get rid of the BAC valve. One thing I am wondering is if you can leave the dashpot on the throttle body? It says to remove it in all the threads Ive read but people have told me not to remove it too. I have an S5 N/A vert with RB Road Race headers and 3 inch single exit cat back with cone filter so lightly modded with stock ports.

10 year bump, nice :D

The throttle body mod is stupid. No good will come of it in most cases.

The few exceptions are the double throttles in the S4 NA. Removing them won't have a negative effect. Won't gain anything either. On the TII, removing the double throttles with a stock ECU will cause hesitation. With a standalone, that can be tuned out.

That said, dashpot removal will cause the throttle to snap shut suddenly. The stock ECU can't deal with this, and the RPMs will dip below idle and then recover. With a standalone, you can use the BAC to mitigate this.

I bumped the thread without realizing how old it was. I am doing the TB mod for the sole purpose of being completely broke and just finding out that my thermowax is bad. By that I mean not extended fully and Im tired of dealing with all the B/S associated with the throttle body. Ive been having problems all summer long with this car not running right. Im doing the mod until I can afford a new TB from an S5 N/A manual with working thermowax. I know it is a dumb mod Im not doing it to gain anything Im just doing it to fix my idle problem. Ive read up on it a good deal before deciding this and at least now I know not to remove the dashpot. I didnt want to in the first place thats why I asked.

being broke, the last thing you need is a running RX-7 :lol:

Hence the reason the car is for sale there bud... Thanks for the unneeded advice by the way. You sound like my parents :facepalm3:. This is my 4th FC and I've been close to broke with the other 3 Ive had and I took care of them really well. I know they aren't the most reliable car and they are money pits but I love Rx-7s and me not having money isnt going to stop me from driving the car I want to drive.

I have the mod done running microcrap seems tom do just fine.

Is Microcrap another word for your stand alone or are you running the stock ECU? lol. Im running stock everything besides the exhaust and intake filter and Im not looking for any performance gains and I really dont care about the throttle response. I read the side effects of this mod and Im ok with not romping on my throttle under 3k rpms until I can buy another TB from a N/A manual FC. Im not deleting the BACV or dashpot just the secondary plates, fast idle cam, thermowax, and double throttle diaphragm. Im going to re-route the coolant hoses as listed above.

This. ^

I just recently went back to a stock unmodified throttle body, reinstalled the BAC, and did a bit of fine tuning with the idle/TPS, etc... I could not be more pleased with the way my car idles, accelerates, and runs in general.

So I did the mod but I still got the BAC. My idle is kinda shitty. Will deleting the BAC help ? Also I kinda messed around with the MAF adjusting screw nd now I don't know where I should set it....any help with that ? Lol my tps is out of adjustment too since the mod .u think that would be affecting my idle?

^ I believe you're not even supposed to be messing with the AFM adjustment screw.

The TPS being out of adjustment will not only mess with your idle, but the overall performance of your car. Turning adjustment screws, nuts, and/or removing things from the throttle body is a bad idea.

And... NO. Removing the BAC will not improve your idle. The bypass air control valve is a vital part of the idle system. It is NOT part of the emissions system.

My car has EP13bt microtech no cat or polution gear running scremmer pipe, hiflow turbo and exturnal gate etc this mod should not be done to a car running standard ecu and you will lose abit of power down low.

lol yah i was messing around... so do u know where i could approximately set the AFM screw?-

also i wanted to remove the BAC just to clean up the engine bay. will it effect anything since its only used for the A/C?...ive already removed the AC