Has anyone else had this experience? You have idle problems and go to turn the screw all of the way both ways and nothing happens.

 

The srew does subtle change to the idle. If you have a somewhat major vaccum leak or any other similar problem then you won't see a difference using the screw.

 

Your supposed to jumper the Initial Set Coupler first, to set the BAC 's duty cycle at a set duty cycle, before turning the screw you mention. Also the idle should be below 750 when doing the above.

 

why do you feel the need to adjust the idle?

I have had my car for something like 14 years, I have never had to touch any of the screws under the hood.

leave them alone!
if you think something needs adjustment there is probably a underlying reason and messing with those screws wont solve it.

Check the basics first.

 

Thanks HAILERS, you're always a big help, I remember reading the whole jumpering bit, I guess I forgot.
I don't think my car has a vacuum leak, I've tried checking everything the best I could, the only leak I think there could be is possibly at the injectors. I just seafoamed the car today too to hopefully help if it was clogged injectors.
My idle problem occurs when I rev it up and let off of the gas in neutral or stop quickly, especially with the lights on. After reading a post earlier in which Aaron Cake addressed a similar issue I think it may be the BAC valve. Does anyone know how to check this, or where I'd even get a new one?

 

Wow. That's the exact same problem I'm having right now. And I even tried to adjust it like you while forgetting to set that jumper in that connector. The BAC valve huh? That might be it, mine doesn't seem to want to compensate for loads all the time either...

 

After researaching real quick on here, I read that it might be the dashpot that is making the idle drop when the clutch is engaged or when you come to a stop...
How bad is your stalling issue? I know mine's real bad, to the point it will die anytime I let off the clutch after it's warmed up, or as soon as I start to drive.

 

Here's the deal. The BAC is supposed to compensate for loads. True enough. BUT, it wasn't ever meant to do the whole job of maintaining an idle. With the initial set couple installed, the engine should be idling *close* to 750 rpm. When you install the initial set coupler it puts the BAC's duty cycle at a set value that won't change as you fiddle with idle screws etc.

IF you fully heat up a engine, then install that coupler, the engine should idle close to 750rpm(repeating myself). IF it does not, then you need to adjust the idle using that screw and whatever else is availabe. Make sure the timing is set with a timing light first.

The idea is, if the idle is approx 750rpm with the coupler in, then when the coupler is removed, the BAC won't have to work is *** off holding the 750rpm idle even when a load is put on the engine later.

Personally I pull the BAC's electrical plug off when setting the idle. Easier.

And let it be known, that if the rpms are in the 800rpm plus range, the bac's air screw (turbo cars) or the dynamic chamber screw (non turbo) are not going to have any effect on the idle speed at all...hardly.

I've never been a bit shy about using the variable resistor on a series four car, to adjust an idle speed.

BAC'S are easy to check to see if they are working. Listen for the hmmmm of then cycling. Turn the key on and listen. It normally will be puttering away.

 

my friends car just dies randomly. idle is erratic and if ur driving and put it in neutral when coming to a stop or slowing down it will just die almost everytime but will start right up like nothing.

 

Yea, that's where I'm coming from, and why I suggested the dashpot. I don't think the BAC would have anything to do with that. And I think that's what the OP is having issues with too. Any ideas anyone?

 

just a thought but have you checked your electrical system.. and have you removed your emissions control stuff (underdriven alt pulley).. if at idle regardless of engine speed im not getting at least 12volts strange things seem to happen to my 7, usually when cold, and as i have an underdrive dual alt pulley i neeed to keep idle above 1k to keep 12volt with say the lights n heater goin.. otherwise it seems to slowly die out till stall

 

Well then, If you think it's the dashpot, the FSM gives a detailed method of setting it. Has nothing to do with an erratic idle though.

And heat the engine up and idle it. Then pull the plug off the BAC. See how far the idle drops. This takes all of approx fifteen seconds to do. Ah, heck, I'll give you thirty seconds. Beats the heck out of sitting in front of a computer *wondering*.

 

True. I also happen to have an erratic idle And I was just looking for someone to give a difinitive answer so I didn't have to go outside and start freezing my *** off in this weather Besides, it was relative to the second question the OP asked /hijack

 

Describe *erratic idle* in some other way if you will. Just an occasional miss? Or up/down idle or???????

Tell you what. Try reading this: http://www.teamfc3s.org/info/articles/idle.html

 

Thanks again HAILERS, the teamfc3s link was very informative. Also, to all who are helping it's an s5 auto NA. I'm reading the FSMs and there seems to be no difference between NAs and T2s concerning the subject, correct me if I'm wrong. I've got a couple of questions if you guys don't mind answering them, esp. HAILERS. How do you jumper the initial set connector? I'm assuming you just connect a wire to one of the pins and ground it on the firewall. Also, what alternatives do I have the checker lamp (which I assume is a Mazda SST.) Ha, nvm I just read how to make one in the teamfc3s faq. It's amazing what you learn when you search. So I guess can anyone just answer the jumpering question? Thanks guys, you've been a great help.

 

There are 2 green plugs located between the driver side fender and battery.The one with two prongs is the coupler.Put the wire from one connector(prong) to the other.

 

Ha, I guess thats why they call it the jumper, thanks satch. Just got done making the test lamp so I guess I'm all ready to try tomorrow. I'll post my results .

 

I just got done with it, I'm going to wait and see what it's like when the engine is not warm. I'm assuming the jumper worked because when I hooked it up and let it warm up the car died and the check engine light was on. I then hooked up the TPS test lamp I made and I could only get one of the lights to turn on sometimes and that was when I cranked the engine and it still did not always do it. I ended up just messing around with the screws with the engine running and tuning it by ear and checking the tach occasionally. It was just running fine, hopefully I can say the same thing later tonight.