I think my bac valve might be bad on my 88 TII, it's causing a low idle.. while I'm waiting on another one would it be bad to leave the bad one intact, either plugged in or unplugged, and just bump up the idle?

 

I think it would be ok as long as you disable it.

 

The BACV only goes into affect when the A/C is on, so as long as you leave the A/C off, you can do whatever you want with it.

 

it goes into effect when the engine is under load at idle, brakes, a/c, heat, ect, bac give the motor enough power to power accessories, check for vaccum leaks bfore you disable it, also check that your cruz control cable it tight, that screwed my idle up for months untill I took it off

 

if the BAC works under load on idle, whats the point of removing it if you want to keep your A/C or whatnot. cant you just clean it out if its running funny?

 

I'm jealous of all you people who have high idles.. I can't even get mine to stay alive..

If the bac valve is only for compensation for accessories then why can't I get the car to idle when all the accessories are inactive?

I fiddled around with the idle stop screw on the TB today and nothing really worked.. I tried several different combinations(amount of turns either way) but it always would stall eventually..

I don't have any vacuum leaks and I'm pretty sure my engine is good. It kicks over fine and drives good. I was worried for a little while when I was reading low vacuum from my boost gauge but it was leaking, it's fine. Anyway, the car does the same thing whether I have the BAC plugged in or not so I thought it was that. I guess I'll try to clean it but why can't I bump up the idle with the TB idle stop screw? or any of them for that matter, I've tried them all..

oh and one more thing, the cruise cable idea sounds interesting.. I accidentally took off some piece, with two cables on it, on the back of the upper intake manifold that may have been misadjusted when reattached.. how can I check this?

 

Could be a number of things, but if it's a problem with the accesories off, it's probably not the BAC valve. There's no need to disable it. The idle stop screw on the TB adjusts how open the primary throttle is when it's "closed". Screwing it in opens the throttle and should raise the idle speed. It's just like pushing on the gas pedal. In my experience, a full turn was all that was required to raise idle by 200-250 rpm. If it doesn't, you probably do have a vac leak somewhere.