does the bac valve always mess with idle when its dirty, or just sometimes? my idle has made car stall or get close when hot pretty much since i got it. i went to disconnect bac valve to clean but wouldn't come off. after i reattached everything i took off, it was idling perfect at 750 rpm. stayed like that for the rest of the day and start of next. about noon it started doing again. any opinions?

 

As the BAC valve is used to regulate the idle, the idle quality can be effected if the valve is bad, the connector is loose, it is clogged with junk, etc.

There's nothing hard about removing the BAC. Use a pick to take the little metal retainer off of the connector and then disconnect, then remove the two coolant hoses and the 10MM nuts which hold the valve to the intake.

 

Pull the elect connector off.

Look into the mating side of the plug while you gently pull on the two wires one at a time. IF you see one of the contacts inside the elect plug move back when you pull its wire, then that contact isn't locked in and is making intermittent contact.....maybe causing your problem.

Or the next time then engine decides to idle low and stay idling low, leave the car idling and go to the elect plug and wiggle it and see if the idle goes up when you do that. If so....intermittent contact is the problem.

 

for aaron cake, i already tried to take it off and it wasnt budging for anything. i even hit it a few times hit a hammer.

for hailers, i'll check that out later today. was taking it to mazda dealer tomorrow to check it. how would you fix the intermittent contact if thats the problem? the only other thing i think it could be is hose from throttle body to BAC is kinda beat up. dont know if that would cause a problem though, as i dont have a coolant leak.

 

No, the water hose attached to the side of the BAC won't cause BAC/idle problems in any way.

I've had wire contacts in the BAC plug not lock into the plug and push back when the plug is installed. Sorry, but I used superglue at the wire side of the contact to hold it in place. You wouldn't want superglue on the part of the contact that mates with the contact inside the BAC. Common sense.

The right way would be to buy another/new BAC plug and install your two wires into that new plug/connector. I know not where to buy such a thing.

If you removed both nuts from that BAC and it didn't come off using hand pressure, then some sorry person glued the BAC to the intake. Can't help you there. But, seeing as how the BAC works, I see no reason to remove it. If you insist on removing it, then you'll have to rap/tap on it with??? a hammer/screwdrivers/whatever is handy. There should be nothing special about removing it after the nuts have been removed and the hose(s) removed.

 

On series 4 it is a square Bosch EV1 fuel injector connector with an offset tab. Same as 87 1/2 - 88 fuel injector, or all s4 water thermosensor. You can order injector clips online or go to carquest and ask for a Bosch fuel injector connector pigtail. My s4 BAC connector was pretty messed up and I just used a new injector connector I had for a fuel system upgrade. You just have to depin the old connector and insert the pins into the new connector. Then file off the offset locating tab on the BAC.




that's what I'm using for my BAC

 

the reason for removing it was that i was going to clean it and reinstall since i read that could cause a weird idle. if nothing else, i'll just have to raise my idle so it wont stall. thanks.

forgot to post before, but i have a s5.

 

The gasket is probably stuck or it has been glued. Just soak it down with penetrating oil and tap it with a mallet. You may need to get a wedge (use something plastic) between the flanges. I assure you, the BAC is only held on via the two nuts.

 

well, taking it to dealer was a complete waste of time and money. i need to find a rotary shop in nj.

 

Dont' take it to a shop it really isn't that hard to take off. We can talk you through it.

As far as new plugs I like these MSD 2400
$25 for 8 at summit or like 6 bucks if you search around. this is for S4 though. I'm going to try and find the ones for S5 soon.

 

^ that's a rebadged Delphi part, which is itself a variation of the old Bosch EV1 fuel injector connector.


http://www.bmotorsports.com/shop/pro...roducts_id/450

Ballenger Motorsports sells a lot of electrical connectors and have a separate section just for fuel injector connectors. The problem is that there are so many variations on the same type of connectors that it can be hard to tell if you've found the right match just from the pictures.

Carquest also seems to have a lot of electrical connector pigtails. I bought a GM fan connector pigtail there. But of course that's GM. They had a huge catalog though.

 

thanx arghx, i forgot all about ballenger. lotsa good stuff there. I didn't mind getting the 8 peice set because eventually im going to rewire my injectors.

Tyco makes nice ones too.

I cant seem to find any "boots" to fit over the ends of the damn things though.

 

i wanted to get a hose clamp to make sure air hose has a good seal. anyone know what size is needed? never bought one before, so dont know if they're universal or not. thanks.

 

That hose is soft enough that a ziptie will handle the job.
Zipties are practically universal too.

 

i was thinking of ziptie too, but wasnt sure if it would seal it. i have extra's, so will try that tomorrow. thanks.

 

i have a microtech 8 on my turbo II. my idle is really high at 1500rpm and i just looked at the bac valve and both nipples/nozzles that are facing away from eachother are hoseless. should i feel suction from this at all? does a microtech eliminate the use of the bac valve? is there another place to adjust idle?

 

Those two tubes (facing front and back) are just a pass through for coolant. You can remove the 2 screws and this piece comes off of the BAC revealing nothing but a flat spot. It's mostly just there for convenient routing/attaching of the coolant lines. If you don't have the lines, you can simply remove this pass through. I removed it when disabling the thermowax system on my S4 NA.

 

It's also there for the same reason coolant passes through the throttle body - to prevent icing from causing the BAC valve to stick, as I understand it.