AAR question - Page 2

Jeff NJ · 07-31-2018, 02:00 PM

I drilled out the rivets and cleaned and adjusted mine without issue. Very simple device inside and easy project to do.

JFairman · 07-31-2018, 02:50 PM

While it's opened up connect 12 volts car battery power to the plug for the heater element wires to see if the bimetallic strip gets hot and bends on it's own and opens the valve disc inside the AAR.

Ambient heat from the engine is not enough to open it. It may start to open a little but it won't open all the way unless maybe the car is on fire. It needs the 12 volt heating element working properly to open it all the way.

The way you said yours was operating backwards in an earlier post makes me wonder if someone took it apart in the past and put it back together wrong. Or something...

The valve hole opening edge usually has some little slots like an E cut into it so the airflow increase through it is more progressive as it opens. I don't remember seeing them in your pic in an earlier post and I don't know if all of them were made that way.
The AAR is bypassing some air around the throttle body while the motor is cold to increase idle speed and keep the motor running on it's own while it's cold.

FWIW some later versions of 930 CIS from around 1986 on with lambda and a catalytic converter in the exhaust also had two 12 volt Pierburg vacuum change over valves (originally made for a Mercedes) that would alter the vacuum advance signal to the distributor.
Pelican has new versions of them with Bosch 12 volt connectors on them.
https://www.pelicanparts.com/More_Info/11747810831.htm?pn=11-74-7-810-831-M244&gclid=EAIaIQobChMIzdvNxqTK3AIVhkVpCh07SQJzEAQYAiAB EgL9zfD_BwE

Jeff NJ · 07-31-2018, 03:00 PM

Jim,

He figured out that there was no power to his wur or AAR because the fuel pump relay died. So now it does move and it isn't backwards, but it seems to get stuck open sometimes.

He posted that in a separate thread, so unless you read that one too, you wouldn't know.

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/1003688-what-i-thought-i-knew-but-didnt.html

JFairman · 07-31-2018, 03:11 PM

Oh OK.
Thanks Jeff.

Handyjay · 08-01-2018, 10:36 AM

I plugged the IC outlet to the AAR and removed the hose from the AAR to observe the movement as the engine was running. Engine would not start. Plugged the AAR and engine fired. AAR only open slightly. It took four minutes to close completely.
Why would having the AAR open to atmosphere prevent the start? Baffled!

Jeff NJ · 08-01-2018, 11:43 AM

That's an expected result. WAY too much air with it open, which makes it far too lean to start.

Handyjay · 08-01-2018, 01:38 PM

I just don't get it. The AAR is connected to the IC normally and the IC connection is above the throttle valve. So why does this affect idle or running? Also, if the IC is removed the engine will not start or run.

1979-930 · 1979-930's Garage

The air coming in is not metered by the fuel plate. So more air than fuel.

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Handyjay · 08-01-2018, 02:48 PM

Of course, got it, thank you.

mark houghton · 08-01-2018, 07:12 PM

Have you yet done as I've twice suggested? Need to confirm if the damn AAR has full motion hot vs. cold. Otherwise you'll just chase your tail. I don't feel there's any way for some previous owner to take it apart and later cause a reverse action by putting it together wrong. It either works in the proper fashion, or it doesn't.
As we Pelicanites are prone to do, we over-diagnose (because we live for that :-) Eliminate the obvious first; broken, stuck, etc.

Handyjay · 08-01-2018, 09:31 PM

Mark, I did flush the AAR with brake cleaner. It closes hot and slightly open for cold start. Closes in about 4 minutes. I tried to make an adjustment to the AAR using a spacer and small c clamp but the pin did not move. May try to be more aggressive as I would like a slower cold start idle. Start cold rpm 1800 and down to 950 AAR closed. Thanks for the input.

1979-930 · 1979-930's Garage

Mark is correct. There is no way to assemble it and make it work backwards. Drilling out the rivets and looking at the way it functions is comical. It’s a Fred Flintstone piece of engineering.
Moving the pin over moves the entire heat plate over. I don’t know what else to call it. The opening is cut into a cam lobe shaped piece that rides on the heat plate. As the plate is heated it warps out of the way and the cam rotates closed by a spring that is pulling it closed. Moving the plate over let’s the cam rotate more and moves the opening closer to the closed position. So it’s not as far open and closes sooner.

I hope I explained it so you can visualize it.

Edit.
And to add to that I tried the cleaning and lubing with no results. That’s why I took it apart. To clean it better. There was still no change. With the new better flowing turbo and intercooler I had to find a way to reduce the air flow when cold. My idle was 2200-2400. I found a thread where someone figured out how to adjust it like I’ve posted.

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Handyjay · 08-03-2018, 09:43 AM

Derrick, thanks for the explanation. My AAR has not been taken apart. I may have misinterpreted that the AAR was full open hot. When I removed the hose to the AAR it appeared to be full open.
It is functioning but the cold idle is higher than I would like. Will try to move the pin to a more reasonable rpm. It is amazing to me that after nearly 40 years of constant electric resistance heating the plate that it actually works at all.