does anyone know what this is?
 

I know it has to do with the idle air control valve, however this thing broke taking off the intercooler, cant.find an actual name for it. Could this be capped off?

Attachment 522055

BAC, emissions removal, block plates

I think I know this one since I've been helping a friend of mine with his TII for several years now. My guinea pig to learn rotary before entering the game myself. That is why I chose to go N/A 1st Gen. LOL

I'm pretty sure it's the sensor that makes your engine high rev for a few seconds after you start it up in the morning. I don't think blocking it off will be a problem.

Sweet, def gonna try blocking it, then to see how it.runs

The BAC is an integral component of the idling system.

air bypass solenoid valve.. it is only on AWS ( accelerated warm up system ) equip cars ( US and oz ) and is for the 3000 rpm fast idle on first start

if you dont have it then you will have to learn the tricks to get your car out of AWS mode else it may foul up without the extra air

Hmmm so if i eliminate wont idle properly?

The BAC has a coolant hose entering one side and leaves the other side and it also has an air supply hose as well (thus 3 hoses in total). In reviewing your small picture it appears that the item is the Air Supply solenoid as mentioned by Bumpstart. The item is much less critical than the BAC. The AWS helps to boost the rpm in tandem w/the BAC to 3k for cold starts when the coolant is above 60 degrees or so. I believe the item also helps the engine when under load due to models that have power steering.

What they said. I guess my newbie is showing. :)

I didn't realize it had anything to do with compensating for power steering load or worked in tandem with the BAC at start up. I just know that we didn't notice any change at idle (other than the initial higher RPM) or how it drove when we disconnected it. What I did read was that a reason for the initial higher RPM was to preheat the cats and I thought that was it.

it will be fine without it, just cap the ports properly or a major air leak will develop.

Thanks guys will try tmrw morning.

idle up for power steering and for aircon on s4 and on some markets s5 is the Air Supply Valve (ASv )
it is on the side of the plenum facing firewall and routes one of the small nipples from intercooler to the secondary mezzanine deck
it will only lift idle by 50-100 rpm

the ABSv on the other hand is responsible for several thousand rpm worth of airflow for the 3000 rpm warm up

the effect of each system turning off can be observed in the warmup decay graph on the s4t training manual ( 4B 31-38 )
.. each device being the plateaus on the graph,, and the wax cams effects can also be seen by the ramp profile

edit 50-100 rpm

cold start-

3000 rpm ( 17 secs.. ABSv, ASv, BACv )
1500 rpm ( .. wax cam and timing retard 120 seconds .. fuel injection period ( duty time ) is also increased for the first 60 seconds )
750 rpm .. idle speed ( BACv )
800 rpm ( ASv .. idle up. PS or aircon )


warm start - ( times vary , one of 3 time brackets set by intake air temp and engine coolant temp)
3000 rpm start ( ABSv , ASv, BACv)

after 2 -5 secs

1500 rpm ( wax cam )

after another 5 secs

850 rpm ( BACv, ASv )

after either 60, 50 , or 40 seconds, bracket depending

750 rpm .. BACv

+

( increased injection duty time up to 60 seconds , increased fuel pressure ( PRCv ) for up to 90 seconds , advanced engine timing for up to 70 seconds )


as you can see the 3000 rpm start is used to both warm up the cat,, but also help purge the fuel lines on a warm start
during a cold start there is increased injection duty time over and above that seen on internal tables for airflow meter , for up to 17 secs before the ABSv's role becomes irrelevant

similar for the warm start,, there is a very brief immediate 3000 rpm period to help purge hot air and hot fuel
injection duty period and fuel pressure are increased , though the ABSv's roll is over almost immediately

however , all the above show you why it is necessary with a stock ecu to maintain all your idle equipment

i would suggest that you may need to start the car in 5th gear to bypass the warmup routines,, or possibly need to flair the motor manually with accelerator for a few seconds to avoid a stall or a foul running condition on cold start

else . a simple solenoid type idle valve from another car could be sized up to replace the mazda culprit.. it is a simple switched to earth to open valve , and you can adjust its flow with a pill in the hose

a fully functioning thermowax will do the job, the AWS system is unecessary.

even the BAC has a stupid narrow range of compensation. 95% of the idle control from cold to warm is done by the thermowax.

Nice thas alot of info guys thanks, ill repost with the results

bac

lol a little late to the party

Lol

not to mention wrong.

Well i tried capin the 2 conections and unplugging the solenoid, also tried running a hose from intercooler to the idle air control valve( so.basically bypassing the solenoid) still no go. Smells super rich in fuel, lots of white smoke coming out the mufflers, im completely lost now.

your issue is unrelated, check everything else you may have touched or broken in the process of working on the car.


if it's literally clouds of white smoke you may just be really unlucky with coincidences.

Well i know it's late but i recently found my problem, lol my flowmeter plug broke Oo thanks for the help everyone