Pelican Parts Forums - What are the AAV and AAR and how do they work?

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What are the AAV and AAR and how do they work?

So I am working on my 911 SC 1979 instaling a UTCIS-V Engine Management System. Install went ok,but have a idle problem after motor gets up to temp.
Control pressure looks ok,about 3.4 bar ,hot,at idle.So ,after about 10 min, of idleing the idle starts to creep up.And levels about 1375 to 1400rpm. It shure feels like a controled air leak? I was think it may have somthing to do with the AAV or the AAR. ???? When cold I can open the idle screw and get 950 rpm,but as it get warm I need to keep closing it down intill it is closed . But still has the high Idle.Let it cool down and I need to open the idle screw back up untill it gets hot again?.
Thanks for the help,Randy

For CIS information:

CIS Primer for the Porsche 911

Screwing in the idle all the way is a sure sign that air is getting in somewhere else. You have a vacuum leak once the engine is warm.

Thanks! Good list and info!
So what would be a good warm air leak? almost seams controled. :confused:

given I spent a lot of money on finding a starting problem

CIS primer is a fantastic resource. I highly advise you to read this for a resource.

First question how do you know the install went ok. Sorry it's the first thought that comes to mind.

I will try to respond to your specific questions in laymen terms. I know others
will have better insight than I do especially the specs for cold vs warm for control pressure. I'm not as experienced. Although I have spent hours reading...

AAR - Auxiliary Air Regulator gives the system a breath of air on a start up. As the vacuum builds up that gasp of air stops. I don't think it operates differently from warm or cold.

AAV - Auxiliary Air Valve is open in the cold. The AAV is electrically controlled that heats up an arm that then closes the valve over a period of time. The WUR and AAV work together for a smooth warm up.

In my opinion you would not have been close to the AAR or AAV installing the UTCIS-V. You probably already know this.

Your idle rises to about 1400RPM.

1. First off is your idle issue new as a result of installing the UTCIS-V?
2. What is the idle at when its cold.
3. Was your Warm up Regulator (WUR) vacuum controlled for the 1979? I think it is if it's like my 1980 euro 3.0L. Are those vacuum lines connected correctly? Others should be able to help.

I think others would say to test the CIS for the control pressure at cold and then measure the changes from cold to warm. I'm sure there is lot of documentation on the UTCIS-V.

I just don't think un-metered air and the control pressure would cause the idle issue to rise.

There is just so many variables and your approach just doesn't seem right unless you start with the basics of testing the control pressures.

And with your UTCIS-V, set up / measuring should be easy with a laptop.

Lastly I thought the idle should be adjusted to around 950 RPM when the engine is warm. So if the idle is too low at cold (if I'm reading your thread right) means (I think) the control pressure is too high when the car is cold ( I think I have this right ). Again others know better.

Good luck and I really would like to know how this goes. I was looking at UTCIS-V but had my WUR adjusted instead. My worry with UTCIS-V (with my Euro 3.0L is the FD is still my weak point). The FD is not replaceable with my part#. I think I would have to go to the EFI kit if I had trouble. For now, mine is working fine.

Good points.
I will log the start up . I will post on Sat.

Yes the unit uses the Vac. and power from the Porsche system.

At start up the line is .9 to 1.2 bar.

At 90 sec. about 2.2 to 2.4.

At 120 sec. about 2.9 to 3.

At 350 sec. about 3.4 to 3.5.

Start RPM 1600 to 2000,then after 5 to 10 sec. about 975 to 1000.

My WUR was damaged from a long park and BAD gas. Just would not start.
So I went with the UNWIRED TOOL.

Thanks for the points.

Just curious...have you set up your CO mixture after the install?

Yes, after getting it running ok,about 10 min. Set to .750mv

I think I found the problem. I pluged the AAR and I now have a good idle!
So could the AAR be removed?:confused:
Can it be repaired?
Could some one post a photo of it apart?
Thanks!

Quote:

Originally Posted by rpmoore2 (Post 5049638)

you got the AAR and the AAV backwords. the AAV is just that, a valve, it is controlled by vacuum. the AAR, is electrically controlled. but, unlike the ICV, which it is confused with, of newer electronic injection, it does not really control the idle, it just raises when cold. then when it is warm it has no function.

set you idle and mixture hot and leave them. if you are adjusting the idle cold, you are going against what the AAR is trying to do.

CP's look good. not sure what an unwired tool is???

when you say AAR, are you talking about the thing between runners 5 and 6 with the electrical connection or the big round disk behind the fuel distributor?
i think you are talking about the decel valve, it is an acorn looking thing behind the throttle body. it can be adjusted or it can be removed. mine was making my idle do sttrange things. i found oil in it after i removed it.

Lotus15,

In your climate you may be able to remove the AAR. I'm not positive, but I think poster Rarlyl8 has talked successfully deleting it in threads of his.

Check out poster Mystery train. He has a great thread on the AAR and its workings, and how to repair it. You may find you simply need to make sure it is getting current, and can actually move internally. Sometimes all that is needed is a spray of lube inside it.

Whatever the problem, always make sure all ignition components are up to scratch, and there are no vacuum leaks.

I don't know how the mV settings relate to CO%, but JW recommends a CO of 3.5% for best performance.

Yes AAR,My BAD!!! LOL
02 volts range from 200mv(Rich) to 800mv(lean) on a 13913 Bosch sensor.
Stoichiometric is about 450 to 475 mv.

Here is some info on the system being used.
UnwiredTools, LLC.

AAR- right side of motor, between 5 and 6 runners. electrical connection on top. only operates when cold to raise RPM's. once warm, it does nothing. it WILL NOT vary the idle after it is warm. it is a very simple device.

AAV- behind the CIS on right side. looks like a big round disk. its only open when the engine is off. it adds air, like putting your foot on the gas, while starting. as soon as it starts, it closes and has no other function. it is strictly vacuum controlled. i suppose it could have a small leak and be opening and closeing, but i have never heard of it.

decel vlave- left side behind the throttle body. it holds the RPM's up when you let off the gas to let them drop slowly. it has been know to cause idle problems, including mine. it was holding the rpm's up or making them go up, cant remember. it can be removed. it is also adjustable as to what vacuum opens it.

i would not remove the AAR or the AAV.

i would check the CP"S better and watch to see if that fancy WUR is changing the pressure. see if it cyles with the mixture. it may be just a small amount, but that could do it.
any of the above parts will not change the mixture, only idle. the WUR is the ONLY thing that will change the mixture. well, if the timing is varying, it could do it, but not likely.

Pulled it down LOOK what I found inside!
http://i916.photobucket.com/albums/a...5/DSC04610.jpg

Yes ,a LARGE piece of carbon. Maybe a jam?
Also looking into the relay that runs this?

Found power problem! Bad crimp(age?) at wur plug. The crimp is for the plug and the line going over to the AAR. What a PAIN!
http://i916.photobucket.com/albums/a...5/DSC04612.jpg

The red/white crimp.

First poor power to stepping motor in UTCIS-V unit.
Then no idle control. (To high.)
Then no power to AAR.

Well,just like me ,she is just getting older?:eek:
Part now on order!:D

that is the AAR.

is your mixture problem fixed?

Pretty interesting. Look at the shape of the opening on the sliding disc in your 79 AAR and then look at my 78 in the 'AAR revisited' link above. It appears that the shape of the 79 disc allows for a higher idle for a longer time.

Good work, and thanks for posting the NAPA connection info.

Thanks.
AAR = Auxiliary Air Regulator

Looks like things are all good now? or for now? LOL
Today was cooler and the cold start went well.About 52 now.