the BAC and idle

Silver86 · 07-26-2010, 01:29 PM

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 · 07-26-2010, 03:03 PM

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 · 07-26-2010, 04:10 PM

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

Silver86 · 07-26-2010, 07:32 PM

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

***TitaniumTT*** · 07-27-2010, 02:53 AM

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 · 07-27-2010, 08:45 AM

Quote:

Originally Posted by 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.

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 · 07-27-2010, 09:32 AM

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 · 07-27-2010, 10:22 AM

Quote:

Originally Posted by 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).

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 · 07-27-2010, 11:52 AM

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

-Ted

07-26-2010, 01:29 PM	#1
Silver86 now what? Join Date: Jul 2009 Location: SE Wisconsin iTrader: (0) Posts: 178 Rep Power: 16	the BAC and idle 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. __________________ 1986 Rx7 coupe - arctic silver - sold aka - 20bforme

07-26-2010, 03:03 PM	#2
LunchboxCritter Simply Rotarded Join Date: Jan 2009 Location: Florida iTrader: (0) Posts: 166 Rep Power: 16	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. __________________ LunchboxCritter - 91 NA to J-Spec TII - 88 FC Vert - 04 Rx8 Disclaimer: I am not a mechanic, and I did not sleep at a Holiday Inn. DO NOT TRY THIS AT HOME!!!

07-26-2010, 04:10 PM	#3
My5ABaby Sigh..... Join Date: Feb 2008 Location: Murfreesboro, TN iTrader: (6) Posts: 2,377 Rep Power: 19	I'm not sure which accessories, but yes, it's to bump up idle under load. __________________ 1986 Sport: 132k miles, 5A (Sapphire Blue Metallic), Tokico Blues, Racing Beat Springs, Custom LED tailights (only S4 LED tails in the world), SSR Mark II, Racing Beat exhaust, S5 black interior, Rotary Resurrection rebuild at 120k miles Community Service Manual RotorWiki "Imagination costs nothing; we could build square locomotives or fly to Mars" - Felix Wankel Yesterday is history, tomorrow is a mystery, but today is a gift. That is why it is called the "present."

07-26-2010, 07:32 PM	#4
Silver86 now what? Join Date: Jul 2009 Location: SE Wisconsin iTrader: (0) Posts: 178 Rep Power: 16	man... i need a 2nd set of hands... cant get this thing to idle for shit. __________________ 1986 Rx7 coupe - arctic silver - sold aka - 20bforme

07-27-2010, 02:53 AM	#5
*TitaniumTT* Test Whore - Admin Join Date: Mar 2008 Location: Right Behind you son iTrader: (4) Posts: 4,581 Rep Power: 10	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. __________________ -The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. *-Angry Motherfcker Mode ENGAGED-**

07-27-2010, 09:32 AM	#7
infernosg IT'S ALIVE! Join Date: Dec 2009 Location: Richmond, VA iTrader: (5) Posts: 811 Rep Power: 15	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). __________________ '86 Mazda RX-7 Base '79 Mazda RX-7 GS