the BAC and idle

[Silver86]

am i understanding this correctly.

when accessories are switched on (headlights, etc), the BAC kicks in to help hold idle.

also....

my car tries to idle at something like 250 and below (im serious) and partially maintains it too... its weird really. is the idle adjustment screw the only way to adjust the idle? the idle seems to be the only thing really keeping me from enjoying and actually driving/trusting the car.

[LunchboxCritter]

I think S4 BAC valves have an adjustment screw. You need to check/set your TPS sensor via multimeter or test light methods. <~ needs to be done every time you adjust your idle screw or bac.

[My5ABaby]

I'm not sure which accessories, but yes, it's to bump up idle under load.

[Silver86]

man... i need a 2nd set of hands... cant get this thing to idle for shit.

[TitaniumTT]

a 250 idle is pretty indicative of one rotor operation. Check the usual culprits, injectors, ignition. The hit the FSM and follow the procedure for adjusting the idle. The n/a does not have the adjustment screw on the BAC, those are the turbo cars.

The BAC is to maintain idle. You want, at least the way I set them inthe aftermkt ecu world, a solid idle without using the BAC valve, use thee BAC valve to maintain it.

[Silver86]

a 250 idle is pretty indicative of one rotor operation. Check the usual culprits, injectors, ignition. The hit the FSM and follow the procedure for adjusting the idle. The n/a does not have the adjustment screw on the BAC, those are the turbo cars.

The BAC is to maintain idle. You want, at least the way I set them inthe aftermkt ecu world, a solid idle without using the BAC valve, use thee BAC valve to maintain it.


hmm... wouldnt surprise me if it were running on 1 rotor...wouldnt also surprise me if i lost a rotor since i last checked. i should just bite the pillow already and buy the 20b. also found out, theres a small air pump under the BAC (cant remember what it was called), well that was unplugged and the hose plugged.

[infernosg]

Can you read 250 RPM on these cars (assuming you are looking at the stock tachometer)? I thought the first line was 500 RPM (so it goes 0, 500, 1000, 1500, etc...).

Any trouble codes? My idle has gotten loopy lately after driving all weekend and I got Code 17 (O2 Sensor Feedback System).

[Silver86]

Can you read 250 RPM on these cars (assuming you are looking at the stock tachometer)? I thought the first line was 500 RPM (so it goes 0, 500, 1000, 1500, etc...).

Any trouble codes? My idle has gotten loopy lately after driving all weekend and I got Code 17 (O2 Sensor Feedback System).


250 was just a guess... usually sits somewhere between the 1st and 2nd lines on the tach... engine shakes like a mofo under 1k (underlying problems i already know about).

no trouble codes... that i know of... never thought of trying to pull a code.

[RETed]

Your car is almost 25 years old.
Do a tune up first.
The idle is the last thing you should be worried about.


-Ted

[Silver86]

Your car is almost 25 years old.
Do a tune up first.
The idle is the last thing you should be worried about.


-Ted



LOL... now why didnt i think of that... i get so caught up in what im trying to figure out that the simple things evade me.