I ran the 12v 5 minutes test on my aar. After the 5 minutes, it closes but still allow very small amount of air to go by. Is that normal ? 

no. keep spraying the wd40 and cycle it fully from freezer to 12v

You mean to tell me all I need is to clean it, and wd40 will do? 

Scotti, it's running good and drives superb, but idling is not stable. It's idle hunting so I decided to test the aar . That's the last thing we didn't test anyway . 

Get it to operating temp and clamp the hose between AAR and manifold with a needle nose vice-grip.

And what to look for ?

Probably to seal it off and see if it still hunts. If it does you either have a leak somewhere else or your fuel mix is off.

Where do you adjust the fuel mixture on the djet??

I was reading this article also. and it may be something that I have to live with.
http://members.rennlist.com/pbanders/idle.htm

The AAR is never airtight close but the membrane should close when it gets hot.
If it doesn't, clean it and also try to readjust it. Some have a nut/bolt that can adjust the close state. Make sure it's hot and close the membrane. Them let it cool down and check that the membrane is open.

PB blaster plus compressed air, add 12 volts for about 10-minues, AAR should close off while the voltage is applied. The AAR will also get to about 130 degrees (used the HarborFreight infra-red thermometer) let it cool down either in the freezer or workbench, then reapply PB blaster and compressed air, repeat the cycle until the AAR consistently closes using a stopwatch. Yes, I did directly blow into the AAR using clear vinyl tubing. My AAR has always closed off to the point no air passes.

It opens and closes but not air tight, If i bloiw air when it closes, just a tiny bit goes tru and that was with a 5 minutes test applyng 12 volts.

No "membrane" in the D-jet valve. It has a rotary valve, which is basically a shaft with a hole from one side to the other. The shaft rotates so that the holes through it line up with holes in the housing of the shaft, which makes for a larger opening. Rotate the shaft the other way, and the holes no longer line up so the opening gets closed off, or close to it.

--DD

So how do you call that turning thing?

Idle mix can be made richer with the idle screw on top of the e.c.u.
Clockwise is richer. If it is lean it will hunt. If you increase the idle speed with the idle valve on the throttle body the hunt may go away. It has been my experience with my d-jet that the mps was out if spec and set too lean, or on one occasion going bad ad was too lean. Some here will say as the book says that it is supposed to default rich and I have had that too one one occasion but then twill not hunt, and you would have a low idle, also lots if soot on the plugs and tailpipe. .you should run more on the rich rather than lean. But I digress. Has your mps been tested for leak? And can you tell if it has been opened up? ? Look and see if the epoxy plug has been removed. If so it has been at some point adjusted and may be set too lean.
Che k those things an let me know what you find. But try the e.c.u. idle adjust. And make sure the hose to the aar is not sucking any air. If you have not gotten it to close yet , you can just block off the hose for now after it is warmed up ans previously suggested.

First, the aar does completely shut off. No air passes thru. None!

Second, wd 40 won't do crap. Use pb blaster like suggested.

The aar won't cause the hunting. Its caused by your mixture being too lean. Turn the ecu knob clockwise one click at a time and let that settle in before you go another click. Repeat till it idles smooth. Then set idle speed with the air bypass screw on the throttle body.

If you can't get the aar to shut completely after using dans method, you may need a unit. I have several.

Curt, the voice of reason....all the above 100% dead on.

I used PB blaster, took a few times, I also took a small pick and moved the shaft to help loosen it up, mine didn't completely close till I did that. That shaft is somewhat spring loaded when partially closed I used the pick to pull the shaft open then let go quickly and let it spring back. Did this a couple of times with the PB blaster finally got mine to close all the way. Supposedly you can pull the shaft out the top and really clean it out and put it back in, but I have not tried this.

Hope this helps
Jeff

While it is out, check the insulation where the wire goes into the bottom for chafing. When they short out and cause problems, this is the spot. Now would be a great time to put in an inline fuse.
Tom

100%. A real weak link in these 40 yr old wires.

If the AAR didn't close completely there would be additional air, same as a vacuum leak. What I do on one that closes but not completely is PB Blaster in then connect it to battery, let it heat up and tap on the top lightly, it usually closes, then disconnect from battery, pour out the PB, add new PB and let it open. Repeat this until it functions properly. Sometimes I cap off one port, fill with PB then cap off the other port and turn it upside down, overnight or even longer. If you continue repeating these steps it will eventually be restored.

A spring? A shaft? Tough to tell exactly what you mean.

It sounds like you are thinking of the 1.8's valve, which has a flat plate inside it with a hole in that. The plate gets turned so the hole lines up with the holes through the body to let the air through.

The 1.7 and 2.0 (and some 1.8s I think!) have a bimetallic coil spring hooked to a shaft. Heat causes the spring to expand, and since the outer end of the spring is attached to the outside of the valve body and the inside is attached to the shaft through the middle, causes the shaft to turn. (This shaft is about 3/4" thick BTW.) That causes the hole through the shaft to align with the holes in the body.

Here's a cutaway drawing of the D-jet version:



Courtesy of Brad Anders' amazing D-jet website: http://members.rennlist.com/pbanders/

--DD