TurbosaurusRX

iTrader: (3)

To begin with, my car had a little bit of an idle issue. Occasionally while stopped, my car would dip down to about the 500 rpm mark, stumble a little, then raise back up to ~750rpms. Usually the problem would occur when I pressed the clutch in and shifted into neutral while coming to a complete stop.

I figured the first step to try solving the problem would be to clean the BAC. I followed the usual FC3S Pro directions. Removed the BAC, sprayed with WD-40, checked to verify the clicking (plugged BAC in and turned key to "ON"), shot down with some brake cleaner and drained it 3 times, then finally reinstalled the BAC.

After re-installing the intake, which I removed to get easier access to the BAC, I started up the car. The rpms shot up to 3000, but while lowering to the usual idle the car stalled. I tried to hold the rpms steady for a little then released the gas to see if it would hold an idle after getting warmed up, but the same thing happened.

Does anyone have some insight as to what may be causing this?

Also, the car is a 91 NA and it never had an idle problem other than what I mentioned earlier. Even if I blipped the throttle to stop the accelerated warm-up process, the idle would hover around 750.

blackedoutFC3S

iTrader: (7)

Sounds like a TPS issue to me and not a BAC valve, did you try adjusting it?

AUGieDogie

iTrader: (4)

First though. Vacuume (sp?) leak. How were your gaskets on the mani? how bout on the BAC?
Second, how is your wireing on the BAC. If the wires touch it will burn out a resistor in the ECU and then you have no BAC control at all.

TurbosaurusRX

iTrader: (3)

Well I removed the intake and lines, reconnected them, fired the car up, and it finally held an idle. I feel like an idiot since I didn't catch the vacuum leak the first time I checked it, but at least I got the car idling again.

Now, the idle will still drop a little while rolling to a stop and shifting into neutral. I checked the TPS and it was a little off, so i adjusted it to within spec. However, the problem still exists. I can live with the idle dropping like it does, but if its an easy fix I'd love to get it out of the way.

Any other thoughts would be great.

Also, thanks for the other suggestions to help get me idling again.

clokker

iTrader: (2)

I recently stripped my entire intake off to replace vac lines and ended up with a similar problem- a small occasional "hunt" at idle.
New BAC gasket (BAC was cleaned just like yours), TPS adjusted properly.

What finally solved it for me was ziptying the metered air air hoses at their connection to the intake tube and BAC valve. Stock, these hoses have no clamps and over time seem to soften up and lose their seal.
Easy to do and worth a try.

HAILERS2

Pull the BAC valves plug off with a fully hot engine.

If the idle isn't reaaaal close to 750 rpm, then make it run at 750 rpm. Then reattach the BAC plug. This way the BAC will not have to work so hard to make up for a engine drop below 750rpm.