Hi guys,
The BAC on a Zenki FC is meant to avoid unstable idle any time but manly for smooth ilde when turnin' on & off accessories such as AC, light...
It does also helps reducing exhauts emissons.
According to Mazda's documents and WOT logic (No more BAC) it does only good thing to the RE.
But many seem to remove it, so I want to know why!
Thermal efficiency benefit? (I don't see why as O2 sensor does the thing and as the afr is constant the heat generated also for there is no change in the ratio of mixture burnt and the heat generated).
Or it is in the dark side ot the moon: it has drawbacks which Mazda forgot to talk about?

Bonus question: is there a special section where I can find some ECU binaries and share mine?

 

people remove the BAC because their stupid and like driving cars with no power steering, emissions equipment or A/C or are too lazy to fix them. If those items are removed there's no reason to have a BAC valve. I had to re-install the BAC on on my turbo car, and i have yet to re-install the A/C emmisions and P/S.

 

i know why

 

I mean it's one less thing to break I guess, but it's a pain in the *** not to have it. Even with no accessories you will be idling lower.

 

i know when i turn my A/C on, my car idles very lean and is SUPER weak. and when its cold it dies frequently with the A/C on (because of the lean mixture)

 

The purity of your logic is sullied in it's delivery.

Wanna call a mulligan?

 

What about the coolant line? Could Mazda have designed it so there wouldn't be a coolant line going to it? One draw back that I see if that you have to clean it when the car is up in age, but that goes with anything.

 

The coolant line doesn't go to the BAC valve, it is a connecting point for the hose from the Throttle body to the water pump, at least on the turbo models anyway.

 

No real benefit to removing it, it is just a stepper motor that opens a hole behind the throttle plates,it opens a certain amount when a/c is turned on it opens a certain amount when the idle drops low, extra so on and so forth same thing as giving it more throttle, like a (IAC) idle air control motor. FYI i don't have it hooked up at all because I am running a megasquirt only issue is the a/c!

 

The coolant line is on the BACV to regulate the temperature generated by the coil inside the BACV.

It surves a purpose during cold and hot starts as well. It will idle the engine up to about 2300-2500rpm

Its by no means for emmisions. The only emmisions help portion it has is idling the engine up to continue the heat up process of the CATs that the AWS starts.

I can't see it doing anything better for WOT runs.

 

It ain't no damn stepper motor, darn it. Cheeez.

 

So If you like AC an PS you're an idiot?

Let's go build road race cars with air conditioning and power steering!

The BAC helps with electrical loads as well, thats why i wouldn't remove it otherwise i would.

 

It does nothing for emissions, it's just for idle speed control.

A BAC valve or a stepper motor valve is fitted to just above every automotive EFI engine ever made for one reason; idle speed control.

There is none, it's just for idle speed control!

Do you see the pattern?

It's not a stepper motor, it's a simple valve that's pulsed open and closed at a constant rate, with flow varied by changing the duty cycle.

 

Mine was taken off by my rebuilder and I'm curious about putting it back on.

What would I need to hook back up (besides the connector) to get it working just for idle?

Would I need to hook up the coolant lines if I don't have my thermowax?

 

The sole purpose of the coolant hose to the BAC is to prevent ice formation at the BAC's pintle. Anywhere you have a high rate of air flow, especially in a venturi (such as a carburetor) you have risk of ice buildup, even with an ambient temp of 50 degrees with high humidity. Ever notice why every car made has a method of warming up the throttle body (most often with coolant hoses)????

IMHO, people should leave the damn BAC and thermowax on their vehicles. If the BAC quits working, clean it or replace it. There should be hundreds of them available used with all these people that remove them. Some might even give you their old one if you paid shipping. For those of us with Megasquirts, there is a much better setup that uses a machined aluminum housing and a Chrysler IAC valve. Very reliable and cheap and it can be mounted anywhere you like.

 

One less thing to cause an intake vacuum leak...

One less thing to cause a coolant leak, although very rare...


-Ted

 

Here we go.....

Eliminate the BACV because you would rather not do the 1-2 year maintenance on the engine to eliminate the possibility of vacuum leaks and coolant leaks.

 

Au contrare...

Who else would buy a $35 SAMCO silicone hose to fit perfectly to a Trust / GReddy BOV kit, cause the GReddy pipe is 7/8", which is slightly larger than the stock hose for the BAC valve inlet...

Since I'm running a Haltech E8, I can tune the EMS to perfectly handle engine idle without use of no stinkin' BAC valve.

You really should keep to your pathetic remove-my-AFM thread.
You seem to like talking in circles and getting no where in there anyways.


-Ted

 

Even with MS, im still using the BAC valve to adjust idle, and I use it for easier cold starting and warmup as well. I really dont see any reason to remove or replace it unless you're just looking for a cleaner, simpler engine bay

 

I removed mine because I think it is ugly....

My car idles slightly low... 650 RPM. But it sounds nice, and never dies. Just idling a little lower.

I still have A/C and P/S. Both work and I don't have to adjust idle.

Maybe when my compression drops a little and my car starts having trouble idling I will put it back on....

If it works... don't fix it.... Mine was being all jacked. So, when I did the S5 swap, I took it off.

 

In fact my question was not a real question as I know the answer
It's stupid to remove it.
For cooler mixtuer it's better to remove thye coolant line through the intake manifold in our very sweet France climate.
For the collant line through the BAC I confirm huys how said it is:
1 Prevent Valve Icing,
2 To maintain a constant fixed solenoid coil temp.

Mazda's also publish documents where they say BAC does helps or is linked to reduced gas emissions. Don't know more but that Mazda wrote it.

Again my bonus question, do you all goes for MS or some doin' chip tuning?

Thanks and please all of you here be more easy with the ones you don't like much
Peace & luv!

 

Lamest reason ever.

It's actually more effort to remove and cap off the BAC valve than it is to replace either the gasket or the hose.

 

It's not especially when the inlet hose is NOT CLAMPED from the factory.
Anyone trying to run higher boost will usually tend to blow that hose off first.

It's one of the first things I check when I come across a bone stock FC.

Lame?
Not in my book...


-Ted

 

So removing it is easier than buying a clamp?

 

OMG, no clamps! You're right, there's no possible solution but to rip it off...