Aux Air Valve and Vacuum Lines questions

[Waterbury]

I have a couple questions regarding the Aux Air Valve. Currently I can only start my car with the throttle fully open (accelerator down to the floor) and then have to give it gas for about 2mins before it finally idles on it's own. Even then it's a rough idle, idle clears up after a 10min drive but is much higher.

In other words; Car only starts with throttle open, stalls out immediately if I let off gas, eventually idles at 1k rpm but rough, idles at 1400rpm after drive still slightly inconsistent.

Upon inspection my AAV was only held on by 1 bolt (lower) and I was able to remove it by hand, so it was not tight. I can see a visible slot for air to pass and can manually open it up, is this supposed to be completely closed when engine is cold? I stuck it in the freezer about 45mins ago and it has opened up slightly. I am also unsure as to what hose connects to the T fitting from the AAV, I put a picture below, not sure what is supposed to be connected to the smaller nipple.

Side note; What use is the A/C vacuum reservoir that has the A/C removed? There is a vacuum line from the Plenum that leads to it and mine was disconnected.

Thanks guys.

 

[Dr.Jeff]

Your description of the AAV sounds pretty much normal. Also try warming it up to around 100* and see how far the gate inside moves. They get dirty inside and can restrict movement.

The vacuum hose to the reservoir behind the seats feeds the dash controls for the heater and AC. Those push-buttons are actually vacuum switches. So if the vacuum line is disconnected you won't have much control of the heat or vent.

One end of the AAV connects to the driver's end of the intake manifold's plenum, next to the cold start valve. The other end connects to the air intake tube near the throttle body, via the tube in your hand (ties in with the breather hose). The valve is warmed through the manifold where it mounts. So if its very loose it might affect its performance some, but not a ton.

Hope this helps a little. Maybe someone can correct me or add more to offer additional help.

 

[Waterbury]

Thanks Jeff, I had tried warming it up and didn't see any movement at all. After letting it thaw from the freezer it has closed up what little it opened from being in there, still same position as pictured when I originally pulled from the car. The hose I was curious about is the one circled below, sorry if I was unclear about which one.

 

[Dr.Jeff]

That little hose connection is familiar but at the moment I don't recall what it goes to. It was plastic on my '85 and snapped off at one time. I believe there is a larger hose from the block vent below (cyclone thing), going up to the really big air tube from the air flow meter, the AAV hose we discussed splices into those, and that little one (in question) leads back to the intake manifold??? I'll see if I can remember and post later.

 

[Dr.Jeff]

The yellow boxes should be where all these larger hoses for the AAV connect, if I recall correctly:

 

[Dr.Jeff]

I took a closer look at some of my parts. The larger air tube (from the air flow meter) has 2 ports under it; one to the block vent and the other to the AAV. The one to the block vent has a plastic attachment and it has the extra nipple for a smaller vacuum line. The one for the AAV has a metal attachment (like the one in your picture) but no extra nipple. So I think mine is different than yours. Also the vacuum line on the block vent fitting is quite small diameter and I think it went to the intake manifold by the cold start valve. There are a pair of little metal nipples there. But I can't remember what it did. I don't keep things stock and little stuff (like emissions items) is usually the first to go.

There were several variations of smog equipment and other changes so it's hard to say exactly where that goes on your engine. Maybe someone else knows.

Regarding your AAV. Try soaking it in carb cleaner and flushing it repeatedly to see if that frees up the valve inside. Also your idle issues could be fuel related rather than the AAV. So go through all the injection systems checks/tests in the workshop manual.

 

[lookforjoe]

The AAV should be wide open when cold and closed (mostly) when hot. The metal "T" nipple feeds the AC idle solenoid.

If you have to keep the throttle open for the engine to stay running, esp. cold it is most likely that you have a rupture in one or other of the AAV hoses, which messes with the air metering. Or the main inlet hose.

 

[Waterbury]

I checked the AAV hoses for leaks and they both passed. I did not check the snorkel for leaks yet. How cold is "cold"? The picture of my AAV is of it at about 75F, inspecting from the freezer it only opened slightly more (maybe double?). Thank you for the diagram, was exactly what I was looking for.

 

[Dr.Jeff]

The metal "T" nipple feeds the AC idle solenoid.

That explains the difference; my '85 does not have AC. My '79 does but it isn't fuel injected, so completely different.

 

[Waterbury]

Since I don't have AC, I plan on just capping off the small nipple. Can only imagine this was creating a little bit of a vacuum issue.

 

[Dr.Jeff]

The Bosch injection on these is very dependant of accurate vacuum readings. Any leaks will cause false reading at the air flow meter, and therefore throw off the mixture settings. Even worn engine seals, leaky gaskets, dip stick not sealing, worn rings with blow-by, etc can all affect it. So ya, a open port like that will have an impact. But your issue sounds a bit bigger than that. Nonetheless, check everything for leaks and seal everything tight.

 

[ng_randolph]

Side note; What use is the A/C vacuum reservoir that has the A/C removed? There is a vacuum line from the Plenum that leads to it and mine was disconnected.

Vacuum from that reservoir is what operates the fresh / recirc flap and the defrost flap in the ventilation system. If you still have the A/C heater box and controls, you would want to keep the vacuum plumbing intact also.

 

[Waterbury]

Upon further inspection there was a slight air leak caused by clamp on the hose that goes from the AAV to the snorkel. I put a new clamp on that then blocked off the small nipple I was previously unsure about. Still couldn't start the car without an open throttle, BUT it does idle 100 times better now. Idles right at 1k without me touching anything, after driving for 15mins it still idles at 1k at stops. The car also starts right back up after a drive without using the throttle. Will keep looking into what might be causing that.

 

[Dan Sarandrea (Phila)]

Upon further inspection there was a slight air leak caused by clamp on the hose that goes from the AAV to the snorkel. I put a new clamp on that then blocked off the small nipple I was previously unsure about. Still couldn't start the car without an open throttle, BUT it does idle 100 times better now. Idles right at 1k without me touching anything, after driving for 15mins it still idles at 1k at stops. The car also starts right back up after a drive without using the throttle. Will keep looking into what might be causing that.

Yep, you have to be ruthless on "false air", which is the term for any air introduced into the intake stream that has not been accounted for by either going thru the AFM or designed into the system in the first place (such as the evaporative emissions control system).

 

[MikeHynes]

I have a couple questions regarding the Aux Air Valve. Currently I can only start my car with the throttle fully open (accelerator down to the floor) and then have to give it gas for about 2mins before it finally idles on it's own. Even then it's a rough idle, idle clears up after a 10min drive but is much higher.

In other words; Car only starts with throttle open, stalls out immediately if I let off gas, eventually idles at 1k rpm but rough, idles at 1400rpm after drive still slightly inconsistent.

Upon inspection my AAV was only held on by 1 bolt (lower) and I was able to remove it by hand, so it was not tight. I can see a visible slot for air to pass and can manually open it up, is this supposed to be completely closed when engine is cold? I stuck it in the freezer about 45mins ago and it has opened up slightly. I am also unsure as to what hose connects to the T fitting from the AAV, I put a picture below, not sure what is supposed to be connected to the smaller nipple.

Side note; What use is the A/C vacuum reservoir that has the A/C removed? There is a vacuum line from the Plenum that leads to it and mine was disconnected.

Thanks guys.

It sounds like you have a vacuum leak.
As you noted plugging the nipple on that T fitting (from the AC Idler Set-Up Electro Valve) is a must do. That nipple feeds additional air to the plentum (not vacuum) to step up the idle, that's one reason your idle was so high. As you can see in the illustration lookforjoe posted above the source of this idle step-up air is after the air flow sensor and that nipple (that feeds the AC Idler Set-Up Electro Valve) should be capped too.
The nipple that feeds vacuum to the AC controls must also be capped if you remove the AC system. (But only, as ng_randolph points out, if you replaced the AC controls with non-AC controls.)
Check that the hose between the air flow sensor and the manifold doesn't have any cracks in it. The connection between that big hose and the crankcase vent is on the bottom of the big hose and hard to see. If you yank on that big hose to remove it, it's easy to crack it there and it's difficult to see.