Help me understand the AAR please.

[Wade Nelson]

"There's NO WAY...."

Famous last words, Fast, famous last words.

Plug off yer AAR anyway for a couple of days and just CONFIRM it's the true and ONLY cause of your erratic idle. What'll it cost you, 20 minutes?

One of us will owe the other one a six pack when this is all over

[Captain Obvious]

FastWoman, I understand the juggling priorities issue completely as I am perpetually in the same situation. I've got so many other things I should be doing that I feel guilty when I'm working on the Z. :paranoid: Stack of cement board and boxes of tile? Been there too... Good luck with the project and hope you get your shower soon!!

As for the AAR impact on idle RPM, now that I think about it, I have to admit that I don't really know how much of a change you could get out of one that is working properly. I've got mine adjusted such that my idle stays about constant at 800 RPM or so as the engine warms up. If I were to open my AAR up more, I don't know how high my cold idle would go. I suspect I could get a pretty high idle though because you see how small of a window I've got past my shutter when cold. I'm using less than 25% of what that AAR could flow.

I bet my cold idle would be 2000 RPM, and as long as it could still close completely, my warm idle should still be 800 RPM.

[TomoHawk]

Higuys,

I was thinking about the AAR and that it opens up as you drive so you end up with high idle even after driving a while, then while waiting at a stoplight, the engine slows down to the warm running speed. So I thought of two questions so far:

1- what kind of material could you use for thermal insulation of the AAR?

2- what would you wrap or cover so the heater stays 'hot?' and the shutter inside stays closed?

For the insulating material, I though that you might use a header/exhaust wrap, which should be available at an AP store. And that part you insulate should be the horizontal, heater tube.

Again, the only alternative that I think would work would be a a valve, either electrically-controlled, or manual.

[Zed Head]

The AAR should have power supplied to the internal heater as long as the engine is running. It's on the same circuit as the fuel pump, I believe. So it should only cool down when the engine is not running. If your idle stays high at a light, it's most likely not the AAR causing it.

[TomoHawk]

I disagree. The AAR will cool down and open almost immediately if you turn off the power, or faster if it has cooling air. The block with the coolant circuit inside is needed to keep the AAR closed while driving. Otherwise it will cool and open a little while driving.

[siteunseen]

I removed that coolant block and my AAR works like it should.

But I do live a little closer to the equator than you so I'm bowing out on this one.

Edited May 4, 2013 by siteunseen

[TomoHawk]

It happens even in august, when the ambient temperature is 80+.

I'm going to try a thermal wrap, unsightly as it might look, to see if it has a positive effect.

[Zed Head]

I disagree. The AAR will cool down and open almost immediately if you turn off the power, or faster if it has cooling air. The block with the coolant circuit inside is needed to keep the AAR closed while driving. Otherwise it will cool and open a little while driving.

I took your thread title literally, so described how it's supposed to work. The FSM description should help, attached. It shouldn't work like your describing yours as working.

[Captain Obvious]

It's conceivable that if the ambient air temp is low enough that the AAR wouldn't be able to maintain enough internal heat to keep itself closed. But I don't think that should be happening at 80+ air temp day.

If your AAR is opening and raising your idle while you are driving on an 80 degree day, then I think there's something wrong inside your AAR.

Have you tried other AAR's to see if you get the same reaction?

I'm with siteunseen... I don't have the heat plate under my AAR and mine doesn't do that.

Edited May 5, 2013 by Captain Obvious

[TomoHawk]

What do you mean by other AARs? A new one? The one I have is only a few years old, and ought to be working. I had checked it on the workbench too.

[EuroDat]

I dont think the AAR is your problem either. The fast idle problem you are having can be easly tested by blocking the air hose after its warmed up. I would fit a temporary hose so I could clamp it shut with vice grips (the original hose might not like being cruched by vice grips). If the fast idle still happens it something else.

[TomoHawk]

There is a much easier way to block off the idle air. You simply loosen the two screws on the metal connection elbow on the throttle, slip a piece of card in there, tighten. There is no need to crush any hoses.