mattnevels

the previous owner had done the TB mod and removed the 5 & 6 Port Sleeves. I got another set of Port Sleeves (Thanks a ton Copandengr!) and I now had much better low end power but still crappy idle. It would die when cold and was jumpy when warm. I removed my Throttle Body and looked in my extra parts the guy gave me and I put the Thermowax unit and fast Idle Cam back on. I adjusted the clearences of the single butterfly valve according to the factory service manual. I then adjusted the fast Idle Cam according to the factory service manual. I then adjusted the fast Idle screw according to the factory service manual. Do it exactly as it said. when I was doing it I thought surely this isn't the right clearence but I did it anyways. I also misread the fast idle cam setting in the manual the first time. Read it carefully. I adjusted the TPS while the throttle body was removed and then reinstalled the Throttle Body. I took it for a test run and it ran great, but when it warmed back up it was kinda jumpy when I got on the gas so I readjusted the TPS after it was warm and everything is smooth now. I disconnected my BAC and set my idle to 1000rpm. Now when I turn on my AC the Idle drops to 750 and everything is more smooth than it's ever been. I think the key was the fast Idle cam and fast Idle settings. They seem to be VERY touchy.

So after checking all the bac crap and soldering a new transistor in my computer I find that my car runs best without the BAC. Instead just keep the idle screws set properly and the TPS set properly. Thanks to all who helped and posted comments!

Matt
86 N/A

vobs

mattnevels,
You said that removing your BAC fixed your problems. Are there any drawbacks to removing it, side affects? Do you have to do the throttle body mod to be able to remove the BAC? I have been trying to fix my idle for the last couple of weeks and I determined that my BAC valve was shot? I just found a possible replacement at I'm hoping a reasonable price. What are my options here? Thanks in advance.
Vobz

mattnevels

In all my research for my Idle problem I found alot of people having problems with their BAC and related components. I spent alot of time making sure my BAC was good and making sure all the related components were good. I even did the transistor replacement hoping that was it.

The BAC just gives the engine more air (which is measured by the AirFlow Meter thus giving it more gas as well) when the engine is under a load. I'm not sure if it only affects performance while idling or not. It is connected to your AC, PowerSteering, Clutch, and a Neutral Switch. The only thing I can notice that puts the engine under any kind of load to require this is the AC. To compensate this I set my idle at 1000 instead of 750. when I turn on the AC the idle drops to 750. If My BAC was connected and everything was working properly the BAC should bring my Idle back up to 1000. This would let me set my idle at 750 and not worry about it dying when I turn on the AC. I find that I like the Idle at 1000 better than 750 anyways so it works good.

I didn't actually disconnect it and notice my problems go away, I was just trying to make sure it wasn't interfering with my tweaking the throttle body settings. I didn't do the TB Mod, a previous owner did so I can't say if that helps make up for the removal of the BAC but I wouldn't guess that it would.
I got my fast Idle settings all proper on my TB and it ran so good that I decided that the benefits of a properly working BAC weren't worth the extra hassle to make it work right. I reconnected my BAC and it didn't do a darn bit of good, and I'm tired of checking into those problems. I know my valve is good and as smooth as my car is now it just isn't worth trying to fix. The only benefit I could see is that My idle wouldn't drop when my ac comes on. I have no problem with it dropping so I say simplify the whole setup by disconnecting it. I'm not going to remove it cause I might sell it someday and I don't want to be like my previous owner and muck things up almost irreversible, so if they want to make it work it's all connected. Less work for me too....

I really was impressed at what a big difference such a small adjustment made to the fast idle and the fast idle cam settings. Too bad you gotta take off the tb to adjust it. I had to make several attempts before I got it all good.

Good luck...

Matt

vobs

mattnevels,
Well since I do not have AC, I may just try disconnecting my BAC valve and see what happens. Did you just pull the wiring harness off or did you do something with hoses? I really don't see how disconnecting the BAC would fix my erratic/jumpy idle problem tho. Since my BAC doesn't "click" (when voltage is applied to it) now, what is disconnecting it going to do? How difficult is it to adjust the fast idle and the fast idle cam settings? How long did it take you to do? I have not checked mine to see if they are set correctly to the factory settings. Let me know about disconecting the BAC. Thanks.
Vobs