AAR Revisited

Mysterytrain · 01-10-2005, 05:29 PM

I wanted to post this modification last month but I got bogged down with the holidays and gigs. Anyway, I have been suffering thru the better part of the Porsche season with an Aux Air Regulator that I felt was closing to soon and dropping my warm up idle speed a bit too low. I had planned to just replace it with a new unit but at the current weak dollar price of $675 I decided I would modify what I had or return to a more elegant solution..the manual hand throttle! There are two forces that you are dealing with. The opening size, the larger the opening the faster the idle [ask me how I know] and the heating element that determines the rate of closing the orifice. My AAR had a heating element resistance of 17 ohms and took only 2 mins to close completely. I had read that 33 or so was what it should be. It made sense..higher resistance longer heat up time = longer time before closing. Once I was able to buy and install a spare used unit off of ebay [ from a turbo and good for an additional 20 hp ] it was time to dig into the little beast. First I marked the disc in its partially open position to serve as a reference. Then, I took the unit apart by drilling out the four rivets. See pics 1 and 2

Once I had it apart I began to understand how the thig worked..think Lionel Trains! So I dug deeper. I removed the large plug on the side of the unit to gain access to the nut that held the element in place. I used a C - Clamp to press the plug into the cavity for removal rather then drill it out and then be force to fabricate a new one. Once it was clear of the aluminum housing I had to nudge it over the the nut to get it to come out. Once you get into this it will make more sense.

I was then able to remove the 10mm nut and free the heating element from the housing. You will need to slide the spring metal wire retainer out of the housing so that you will have enough slack in the wire. It is the large square black object at the center foreground of the next picture. Also notice how I tapered the inside base of the large plug to make it easier to remove the next time. Don't go crazy the plug needs to seal when its re-installed.

When I saw the hand wrapped wire on the element I knew the AAR could be modified. I went online and searched for resistance wire and found a company in Naples, Florida that would sell short lengths. The Company is called ..dig this...Pelican Wire Company !
http://www.pelicanwire.com
From the resistance measurements that I had and the existing wire diameter I determined I needed 30 gauge Nichrome 80 wire with double glass, silicon insulation. This wire had a resistance of 6.48 ohms /foot and sold for $20 for 25 feet. Once my order arrived I started on the rewiring of the element. I unwraped the old wire and cleaned the sleave and applied a small amount of insulating varnish to help tack down the wire.

Then I measured out about 6 feet of the new wire and measured the resistance. Which came out to 38 ohms. I wrapped the wire neatly and tightly around the sleave for a nice even layer [ while the varnish was still tacky]and then started a second layer until I had used up the length. I let it dry.

I re-installed the heating element and then replaced the extra insulation on the wire ends and soldered them to the connector.

While the large plug is still out of the housing you can adjust the position of the heating element and its relationship to the opening. This is where my marks came in handy.

I buttoned the AAR back up and tested it before I installed it. With the reduced opening size it still took the AAR 5.5 mins to close completely! Installed on the car I'm getting cold start idle of about 1250/1300 rpms for the first 40 seconds or so then it drops to around 1K /900 until the engine warms up [past the first tick on oil temp gauge]. Best of all no more stalling!
So far so good. YMMV
Peace, Ron
www.mysterytrain.org

Elombard · 01-10-2005, 05:39 PM

Can I buy your old turbo AAV for the 20 HP :-))

Nice - you electical guys baffle me???

Mysterytrain · 01-10-2005, 06:04 PM

Ok, maybe it wasn't 20 hp but it sure feels like it!

Mysterytrain · 01-11-2005, 04:25 AM

Tony..your mailbox is full so I will answer your question here.
For lack of a press I used a C-clamp. Basically, I set up the clamp so that the screw side [with the pivoting base, which was a perfect fit in my case] was positioned over the large plug and the stationary base of the clamp was on the opposite side of the housing over the small plug. I also had a thin piece of oak between the clamp and the small plug side to protect the housing. By tightening down on the clamp I was able to push the large plug inward until it cleared the thickness of the AAR housing. Hope that is a bit clearer? Once the plug is inside the housing I had one other small problem. The bottom on the plug was concave and was hung up on the 10 mm nut..there still wasn't enough clearance for the plug to slip between the nut and the housing and fall free. I was forced to gently pry the plug over the nut to free it. Don't bugger the hole doing this. I then cleaned up the buggered spot on the bottom of the large plug with a file and slightly tapered it so that if I had to repeat the process the removal of the plug would be easier. Worse case scenerio would be to have a new plug machined. I guess if you had the skills to machine a new plug you could just drill out the old one rather then use my method. Again, you need to be careful because the plug needs to seal. If it doesn't, there will be an air leaks and that will effect the idle speed.

fireant911 · 04:18 PM

This is truly representative of what makes this board so great - innovative individuals who use their expertise and share the results so that many others can benefit from their experimentation and eventual success. I have so often wondered what the insides of this 'mystery' device looked like - and now the answer clearly exists in front of me!!!. The write up and pictures were excellent and I, as well as many others, will be archiving this procedure for when we need to overhaul our Auxiliary Air Valve. You have saved many appreciative people a considerable amount of money with your project. Thanks for sharing.

echrisconnor · echrisconnor's Garage

Great post! A couple years I did a similar sort of thing with my AAR, only I was just trying to change the amount of opening I got. I was able to open mine and bend the bi-metallic spring a little and make the device close fully.

One thought. Instead of pushing the plug in, you could do a similar procedure for what is done on the WURs. Drill a small hole in the plug and tap it. Then put a large socket, or other spacer with a larger diameter than the plug, over the plug and use a nut on a bolt to pull the plug out. Use a shorter bolt when done to seal the hole.

Thanks for posting this!

Paulporsche · 01-11-2005, 11:37 AM

Great work, Ron.

Mysterytrain · 01-11-2005, 12:30 PM

Thanks guys..it was a pay back for all the help I get here!

Erakad · Erakad's Garage

I'm absolutely amazed...great work. This board jsut keeps on amazing me...how do you guys come up with this?

autobonrun · autobonrun's Garage

I love innovative solutions that are nearly free.

Two questions for you. In your second photo, there is a metal prong that is sticking out. What is it for and what does it connect to?

How does the heating element move the damper? Does the element expand or what?

Mysterytrain · 12:49 PM

autobonrun,
The prong in the part marked 2-2 is the heating element. It pushes against the brass colored disc [ note the little nub on the disc ] that is visible on the part on the right in the picture. The spring is also helping to pull the disc into the closed position. When heat is applied to the element it loses its spring tension and moves to the left as it starts to close. Wish I had the ablity to label the parts. Hope that helps.
Peace, Ron
www.mysterytrain.org

Tim Hancock · 01-12-2005, 04:22 AM

Nice Ron!

DIY selfers rule! (anyone can dump thousands and thousands of dollars into a car, but not so many can figure this stuff out on their own)

BeeBeeper · 02-10-2005, 06:21 PM

I have tried everything and it seems to be the auxillary air regualtor. I am in the process of buying a whole CIS system for hardly anything. The first thing I will try is test to see how it the auxillary valve opens and closes. If it stays open for a period of time and has about 35 ohms I should be okay. If not I am going to do a reconstruction per your article on "Auxillary Air Valve revisted".

By the way is your valve still working after your reconstruction. Great article and great thinking. It is nice to see someone thinking how to make something better. Why pay $500 when you can by with $20.

Ron

BeeBeeper · 02-10-2005, 06:36 PM

Well, I did not get the CIS System as i hoped on E-Bay. I guess I will have do a reconstruction on the one I have on my car.

Ron

boyt911sc · boyt911sc's Garage

Beepbeeper,

Have you tested your AAR? What are the problem/s you're experiencing. I almost bought a new AAR because all the symptoms pointed to my AAR. What I found out after a very lengthy time was a slight vacuum leak on the AAR hose connection.

Replace it only if it fails the tests.

TD

BeeBeeper · 02-10-2005, 06:53 PM

Thanks for your advice. I plan on taking it off the car and running a test with an ohm meter first and then hook a battery to it and see how long it takes to close. This should tell me the story.

I have a 1983 SC. I starts up at about 2000 RPM's, and will run like this for about 2 minutes. Naturally I get it going right away. If I keep going like on a highway it will warm up and run fine. I f I have to stop or get stuck in traffic the RPM's will drop to 400 RPM's and start backfiring and running terribly. When this happens it takes a long time to warm up and will not straighen up until it hits the first mark on the temperature guage, sometimes 15 minutes.

My mechanic checked the pressures on the fuel system, WUR and they all seem fine. I will check the hoses.

When you found the leak , was your car running similar to mine??

Ron

Mysterytrain · 02-11-2005, 07:52 AM

Ron,
That sounds like the AAR is completely closed before the engine reaches the first mark on the temp gauge..this is the same problem that I had. I'm assuming that once your car is warmed up it runs well. If that is the case I would have a look at the AAR. Its not too difficult to remove. Once on the bench you can apply 12 volts to the connector and time how long it takes to close.
Peace, Ron
www.mysterytrain.org

BeeBeeper · 02-11-2005, 01:52 PM

Mystery Train,

I got lucky while I was out of town and found a brand new Auxilary Air Regualtor for only $197 at a Porsche Dealer. It will be in a week.

However, I am would like to know if your innovative idea will work on my car. As soon as I put the new one on and working fine, I will buy the wire and do a job just like yours. You are right, the technology is not that complicated, however it takes someone that is thinking to go for it like you did.

Thanks for your help. I will keep you posted.

Ron

BeeBeeper · 02-13-2005, 11:58 AM

I have done testing today. I took out the AAR and tested it.

This is what I got :

38 Ohmns at post on AAR
I hooked it up to my battery with leads and the valve was open when I started( About half a moon). In 5 minutes it was completely closed.

While looking around the engine compartment, I noticed that the vacuum hose from the WUR was disconnected at the air box. I cut it about an inch and put it back on the connection by the air box. Real tight right now.Now I am wondering if this was my problem all along.

I checked the voltage at the AAR plug with the ignition on. I am getting no voltage.

Should I get a 12 Volt reading there with key on.While looking around the engine compartment, I noticed that the vacuum hose from the WUR was disconnected at the air box. I cut it about an inch and put it back on the connection by the air box. Real tight right now.Now I am wondering if this was my problem all along.

I am int he prcess of check all the hoses for leaks. If someone is on the net now, it would be great to get a reply from one of you Porsche experts.

Thanks,

Ron

boyt911sc · boyt911sc's Garage

Ron,

Are you using a voltmeter or a test light? Make sure that the wires to the AAR has both voltage and ground. Finding a vacuum leak is not easy. Sometimes you need a little bit of luck to locate it. I used propane or starting fluid to locate the problem. Be very careful!!!!

What's kind of problem you're having now?

TD