AAR question

Handyjay · 07-25-2018, 04:25 PM

The AAR on my 930 is wide open when warm, nearly closed when cold. Is this a repairable issue. I haven't taken the AAR apart yet to see what's up. Look forward to and appreciate all responses.

1979-930 · 1979-930's Garage

What is the issue? Idle too fast when warm or cold?

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Handyjay · 07-25-2018, 05:58 PM

Too fast hot. I have blocked off the AAR from the IC. Idle ok now when started cold. Thanks
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mark houghton · 07-25-2018, 06:47 PM

Doesn't make sense. Should be wide open when cold to let some air into the manifold and sustain high idle, then slowly closes as it warms up to drop the idle. What your symptoms suggest is that it's wide open all the time...warm or cold.

Handyjay · 07-25-2018, 08:34 PM

Mark, the valve is nearly closed cold, normal I think. Warm wide open. It does not make sense. I will open it up and see what is going on. Heat closes the valve, either from the resistance wire and or the engine heat, right? In the past years the AAR was just open enough for fast idle on cold start.

T77911S · 07-26-2018, 05:37 AM

you are certain it is open when hot and closed when cold??
I don't see how it could be the opposite

it gets its heat from the electrics. not enough engine heat to really effect it.

1979-930 · 1979-930's Garage

Have you tried setting the idle at the throttle body? I would lower the RPM there first.
If you need to adjust the AAR below is a post from my thread. After the Long Neck up-grade the air flow was too good. I had the throttle body adjustment completely closed and the idle was still too high. So I had to adjust the AAR so it wad more closed cold and hot. I can fine tune idle at the throttle body again now.
You can lower the air flow through the AAR by pushing in the smaller pin on the side of the housing. The larger cap is access to the nut. this moves the heater plate over and allows the cam to rotate closed. It also make the AAR close sooner.
I would go a little at a time because the only way to pull it back it to take it apart. And it is a biotch to do that.

Quote:

Originally Posted by 1979-930

So third time is a charm for adjusting the AAR. I learned the small pin can be pushed in to close the opening and reduce idle RPM. It also fully closes sooner. I think the new turbo and long neck increased air flow at idle causing the bypass to need adjusting. My cold rpm was 2,800!!!

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Handyjay · 07-26-2018, 07:51 AM

In order to control cold idle I had the idle adjustment all the way closed. I will take a look at the AAR see what the pin position is and try an adjustment. Thanks for the detail and pics.

1979-930 · 1979-930's Garage

Sounds like the same problem I had. I used a 1/4" drive extension and hammer to tap it in. I wanted something flat so I didn't distort it.
If you can rig a battery to it and warm it up you can adjust it while warm. That way you will know it fully closes when warm. They sell the Bosch connector at Napa.

mark houghton · 07-26-2018, 07:36 PM

Another easy way to test its function is to take it off the car, put it in your refrigerator, and when cold see that the window is fully open. Then, alternately, stick it in a warm oven (like 200*) and see that it mostly closes. Adjust appropriately from there, or alternately take a sledge hammer to it.

JFairman · 07-26-2018, 10:05 PM

It's real good that you or somebody drilled out the rivets that hold the AAR together and replaced them with threaded fasteners. Now it can be easily taken apart and serviced.
Looks like plain old silver cad plated nuts and bolts or screws were used.
4 stainless steel allen head bolts and nylocks would look a little nicer there

T77911S · 07-27-2018, 05:08 AM

if it is working "backwards" is it possible to take it apart and put it back together backwards?

this would definitely go down as a first.

this would go down with the guy that read a dial gauge backwards and advanced my cams 15 degrees in my 2.7s

Alan L · Alan L's Garage

It is a while since I pulled mine apart (drilled the rivets as above). But the bimetallic finger sits against a lug on the bottom of the disc and the disc is held against the finger with a spring. So as the finger moves, the disc has to follow. Maybe it is possible the finger has been inserted wrong way round - is flexing the wrong way? But the rivets would have to be drilled if it has been apart before. The bi metallic strips give it an orientation to flex in one direction. When it is cold the finger is near to straight. Maybe see if you can ping it open with a small screw driver in the near closed gap. Should be able to.
As Mark says - fridge /oven. You can visibly see it moving when out of fridge or oven. But it should be completely closed when warm and partially (1/3 approx) open when cold.
Alan

1979-930 · 1979-930's Garage

Quote:

Originally Posted by JFairman

It's real good that you or somebody drilled out the rivets that hold the AAR together and replaced them with threaded fasteners. Now it can be easily taken apart and serviced.
Looks like plain old silver cad plated nuts and bolts or screws were used.
4 stainless steel allen head bolts and nylocks would look a little nicer there

Sometimes you just use what you have available in the garage. Why the heck else do I have bins full of bolts. And the stainless stock always runs out first...

Handyjay · 07-28-2018, 11:53 AM

Derrick, if I move the pin in to far how do I correct this? Is the smaller pin on the left side connected to the larger pin on the right side? Could one use a small C clamp and socket to press the larger pin in slowly? I checked reconditioned AAR for more than $1,000. Yipes.

1979-930 · 1979-930's Garage

The pin on the right is actually a cap that covers the nut that holds the metal plate. If you push it in it does not push on the nut. if you push it all the way in you have to break the edge of the cap off to slide it past the nut.
Hind site I would drill and tap the cap to install a small machine screw. You could pull the cap with the screw and seal it with the screw.

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Handyjay · 09:57 AM

Just checked out the AAR. Supplied power to AAR and it took about 4 minutes to close completely. Returned to the partially open position after power disconnected in about 3 minutes. Still at a loss as to why it was fully open hot. Will continue to check it out. Thanks for all the input.

Handyjay · 07-30-2018, 03:18 PM

The AAR seems to be working ok except for 1800 rpm idle on cold start. Will try to push the pin in a little to slow it down. Why I had a full open on hot engine I am baffled.

mark houghton · 07-30-2018, 05:14 PM

Too fast hot. I have blocked off the AAR from the IC. Idle ok now when started cold. Thanks

Rethinking all this: Your AAR is in need of lubrication. Stuck in the fully open position and never closed as it should when hot. Or, at times, vice versa. Worn out, gummed up, take apart and hose down with WD40 or your lube of choice. Test in oven/refer to see the action afterwards. Maybe as simple as that.

Alan L · Alan L's Garage

Yes, stuck open. Most likely explanation. They can get sticky/gummed up. remove it, poke a small screw driver in the slot and tweek it back/forth. It should move open/close freely. If not try some carb ccleaner, brake kleen etc to de gunk it. If that doesn't work, need to drill the rivets and open it up and clean it properly.
Alant