to the engine and have it stall out when I try to accelerate. The car will die even when it is not under a load. It is getting gas/air/spark... any other possibilities...

 

I doubt it. Just pull the bac plug off and have a go at it. If it still has the problem....it ain't the bac.

 

What else could cause this then? I am kinda stumped...

 

The air bypass solenoid valve MIGHT cause "too much air" if the ECU is energizing it when it doesn't need to be, because it bypasses much more air than the BAC. But this theory of yours sounds funky. The air bypass valve only opens during starts, power steering turns, and A/C on as far as I know. You could always pull the connector off of it too, for troubleshooting. Or you could be reading everything out from the ECU (BAC, APB valve, or whatever else your heart desires) to troubleshoot your problem. See section 4 of the FSM (S4 cars, anyway)

 

"Too much air" is not going to cause the problem you describe. If the BAC valve is held open for some reason (or leaks like mine did), you'll simply have a high idle speed.

 

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Got any suggestions on what would?

 

How 'bout that DIY TID? Have you checked that out real good? And all other big lines, for that matter.

 

AHA!! I think this is exactly what is causing my high idle problems. Last year I put in a 13BT in a GTUs and installed block off plates from K2RD. Anyhow, I noticed that the guys who did the install broke off the top bolt for the BAC block off plate so they just installed with 2 bolts instead of 3 and used silcone gasket. Anyhow, after a year I finally started this thing (another story in itself) and it idled fine, around 1000 RPM, then the other day I started and it idled at 2500, then another time when I test drove the darn thing idled at 2800. I was stupified because I checked the TB and the throttle was all the way closed and the TPS reading on the Microtech said 0%. Today I drove the car on the road and boosted it slightly (4psi) and the idle jumped to 4K, then boosted it again and the it went up to 5K. When I managed to park it I saw that the top part of the BAC block off plate had opened up a bit from the silicone gasket these clowns had used. So, I'm hoping "BAC Valve is held open.... or leaks" is the culprit. I'll have to drill and extract the broken bolt and retap but at least I'll know that could be the problem. Sorry for the long post guys.

 

BAC's have two attach fittings......the ACV has three attach fittings.