waysrx7

I've been trying to get my new '84 se ready for summer and I would like some help trouble shooting the BAC system.

Symptoms: Idle keeps dropping with increased load, ie turn on lights and heater and it idles at 400 or so.

First: I removed the BAC valve and checked it as per FAQ, moved freely as described.

Second: checked the vent solenoid valve, could not blow through it without battery power and could with battery power as per FSM.

Third: Tried to blow through the vacuum solenoid valve (VSV) without battery power and I couldn't, FSM says I should be able to. I then unhooked the other hose connected to the VSV and tried to blow through it again without battery power and I could easily do so.
Does this mean the VSV is okay and there is a block somwhere else?

Just hoping to speed this fix along so any ideas are welcomed.

cmanns

isnt it normal for the rpms to drop with lights and heater, alt is generating more power

Not sure if the 1st gens would bump up the idle, on my fc the rpms dont go up, just go down when i turn on lights n such

waysrx7

Ya the BAC is supposed to compensate for the increased load of lights, heater, radio, and whatever else to keep your idle at 800 rpms

slow5oh

yes, it should compensate completely. I am still learning the gsl-se system, however, every problem if fixed on my car to get it running right with the exception of one was a vacuum leak. I would check vacuum. Also, not suggesting this will help because i certainly dont know this syste well enough to speculate, however, the BEST repair i did on my car by far was changing all intake gaskets. made a world of difference.

comet909

Have you read David Lane's solving gsl-se idle problems?

Might try this...

Option 1: Adjusting the Air Supply Valve
This is not necessary unless you have just cleaned the BAC and Air Supply Valve, and you still have a problem with idle dropping below 800 rpm but only when the air conditioner compressor is engaged.
Before reconnecting the Vent and the Vacuum Solenoid Valves, disconnect the electrical connector to the Air Supply Valve. Hook up the two leads to the battery. This will open the valve and let more air into the Dynamic Chamber. Look for idle speed to increase to the range of 1,000 to 1,070 rpm. If outside of that range, the adjustment screw is under a black plastic cap (if the cap is still there) on the side of the Air Supply Valve.

Its' an idea.

74RX4

iTrader: (10)

The rest of that excellent article is here.
http://mrmazda.no-ip.com/gslseidle.html

waysrx7

Ya, I read that article. I thought the air supply valve was just to compensate for when the air conditioner was turned on and my air conditioner isn't hooked up right now (no belt to compressor). But I will look into that tonight.

It also doesn't explain why I can't blow through the vacuum solenoid valve.

Edit: Also is air supposed to freely move through the 'chamber' under the dynamic chamber that hooks up to the BAC?

comet909

Oops, when I read your post and saw "heater" I thought "AC"

My bad.

I'm pretty sure that air is supposed to freely move through the 'chamber' under the dynamic chamber that hooks up to the BAC. At least when the BAC is open (car is at idle). Now when your driving and not idleing it would seem that the bac should close and no air should be passing thru there. Thats the way I understand that it works.

waysrx7

Well, I looked over everything again and the only place for air to go when you blow through the vacuum solenoid valve is back through the vent solenoid valve so I rechecked it. Last time I could blow air through it with battery power and now I still can but there is noticable resistance and I think that is my problem.

If anyone has a spare vent solenoid valve pm me, it looks like I need one.

mjm4jc

It might not be a bad idea to post a "WTB" in the 1st gen parts section.