Ok so i just bought another fc. This one is an automatic s5. Got it for pretty cheap. Now it starts and runs. But when i put load on it the idle drops. I put it into park or reverse the idle drops alot and sounds like its about to stall so i hold the gas a bit. Would this be the a bacv problem? I think it is but i just need a second opinion on it. It also likes to rev up n down at cold start but idles normally after like a few mins.

 

most likely its the BAC but could be TPS adjustment, and alot of things.

 

You said when you put the car into "park" or reverse it bogs down. Do you mean "drive" and reverse instead because "park" and neutral should cause the car to idle higher than while in gear. Also, does it bog down when the car is in gear and you press on the brake pedal? If so try disconnecting the brake light switch located on the brake pedal and then try to recreate the same situation and see if it still bogs down. You would need to do this when the car is completely cold as in perhaps another day if you started it up already today.

 

oh i meant drive not park. Yeah it bogs down a bit when i press the brake and its in gear. I tried it when it was cold. it didnt raise idle when i put it in gear. If i disconnect the brake light switch i cant put it into drive or reverse cause of the shift lock

 

im leanin towards the bac because should that raise the idle when load is put onto the car?

 

With respect to the brake switch I meant just removing the black plug which houses the W/G and G/W wires which would allow you to move the transmission setting because I just tried it. I asked you to do that because the brake pedal will often times lower the voltage output when depressed and the BAC is supposed to recognize this one way or another and to compensate for the drop. I have the same bouncing idle which last for a few minutes upon startup and then goes away and I've tried to understand what is the root cause. What I did was something you cannot do unfortunately and that is I readjusted the Variable Resistor to run more lean at idle while the car was in gear and it stopped the bouncing or so it appears. If you were to take a pair of needle nose pliers and gently squeeze the BAC hose fully closed when the car is gyrating it should tell you if the BAC is a contributing factor to your problem or not.

 

ahh.. you have an s4 then. thanks. I know what you mean bout the brake pedal lowering voltage output. Ive seen worse on saturns where the brake pedal and fuel pump share a ground or something. When u press the brake the pump dies haha. ill see what i can do later after work.

 

So i finally got the chance to work on the car today. I pulled out the bac and put power to it. It clicks. But when i tested the ohms it read 27.38 or something like that. I decided to clean it. It suddenly started to read 71.something. I read that the readings should be 10.7 - 12.3. So im pretty sure it has to be a bac problem. Just need some extra feedback on this.

 

Browse the FS section. I see BAC valves on there all the time. Make sure you get an S5 N/A Bac.