When warm my AAR closes, not sure what the AAV is doing - (look for lots of pics)

[acapella8]

Okay, I'm in my third day of CIS hell. It started Friday with the replacement of the Green Wire from Hell.. That however is fixed now.

After 3-5 minutes of idle my AAR will close, I took this of the AAR with a mirror:



The AAR will open up again after it cools - so AAR is working.

Here's what I need help with, the AAV is what I do not know how to look at or trouble-shoot but this is what I did.

If I leave the engine at idle for more than 5 minutes, eventually it will raise idle, lower, raise, lower, sputter and die.

BUT HERE'S HOW I FIXED IT AND WHAT MY QUESTION IS:

If I close off (black tape) the AAR, and close of "MOST" of the line that connects to the AAV - I get perfect idle, all the time, perfect running engine.

Here's what I had to do:





If I close off the end of the vaccum line (that eventually connects to the AAV right?) EVERYTHING WORKS PERFECTLY.

Question: Do I have a bad AAV? -

Queston: Can I even get to the AAV to service or clean or replace? It looks hard to get to.

And yes, I did do a search on AAR and AAV - a LONG one. here's what I spent last night and this AM reading:

[ruf-porsche]

If the engine has warmed up and you remove the hoses from the AAV and plug the hoses does the idle change? If it does than the AAV is leaking. Only fix is to replace the AAV.

PM me with your email address and I can send you a PDF file on troubleshooting the CIS for a 911.

Hey you're located in She Car Go also. Cub fan or White Sox fan?

[acapella8]

SOX - Winning Ugly .5 ahead in WC race. I'm sending you a PM now.

Is the AAV a piece that a DIY can replace?

[ruf-porsche]

The item second from the right is the AAV. looks like a couple of bolts hold them onto the engine. Should be just an easy diy.


EDIT
Tom, I think that the pictures you posted earlier is the AAR and not the AAV. The AAR needs to be completely close when the engine is hot. If the AAR is open, air is entering like it was a vacuum leak.

[Mysterytrain]

I've attached a vacuum diagram showing the lines that you have blocked off.



My feeling is that the AAR [part 3] is leaking and not the AAV [part 2]. From what I have read engine temperature is not enough to keep the AAR closed, the heating element needs to be working. Remove the connector and measure the resistance at the two terminals on the AAR. It should be something like 15 to 25 ohms. If that checks out then you might just need to clean up the sliding door so that it seals.
When vacuum is provided from vacuum source [part 10] it closes the flapper door on the AAV [part 2]. Air continues to be pulled from the rubber intake boot thru the AAR this provides a fast idle for warm up. Once the AAR has heated up and rotated the sliding door into position it cuts off the air supply but it relies on vacuum to seal it shut. Any goop on the door or the opening will prevent it from sealing. Once the engine is warmed up it doesn't need much of an air leak to make the idle hunt.

AAR Revisited

[ruf-porsche]

Correction

The AAV is item 2. Item 4 is the thermo valve.

[Mysterytrain]

thanks ruf I always mix up my 2's and 4's before my third cup of joe...all fixed.

[RarlyL8]

You might bipass #2 (AAV) completely and connect the back of #3 (AAR) directly to #10 (Vac) and see how that works.

The AAR does not close completely on some models - it allows a very small amout of air to bipass the throttle at all times. If this is the case for your car the engine will require a small vac leak somewhere in order to idle properly unless tuned to compensate. If the AAR does fully close on your car then the AAV may be performing that function. Either way you will need to consider that function when bipassing these components.

[acapella8]

Brian, Ron, Ruf, Jim & all the rest,

I have bonded with my 3.0L for getting at the AAV was the single most difficult operation I have done thus far - on today the anniversary of my first year of 911 ownership!

After nearly 4 hours of effort: (I know , I'm slow)












Here are my questions:

1. Rarly8 (Brian)- I want to take your advice and will not be reinstalling the AAV as you wanted me to do in your emails.

So.......what is the best way to block off the ports and have proper vaccum?

PLEASE NOTE THAT I HAVE LABELLED EVERYTHING:

If possible, use small words/phrases like, "Tom cover/plug T, and cover/plug "B", but leave H connected as is..."etc..etc.

I think I can only comprehend small words relating to CIS at this point!

2. Can anything be learned by the last picture of the AAV?

3. What is the best way to block off a port? Tape or plug? Any advice here will be most appreciated as always guys.

Tom
(celebrating one year 911 owner as of today 9/5/06)

[RarlyL8]

Simply remove the vac hoses (both of them) from your AAV and plug them with a bolt. Leave the AAR hooked up as per factory spec. Fire it up and see what happens. Bipassing CIS components is an easy way to verify function and is just as easily reversible.

[ruf-porsche]

Originally posted by acapella8




Here are my questions:

2. Can anything be learned by the last picture of the AAV?

Tom
(celebrating one year 911 owner as of today 9/5/06)

NOPE

Happy Anniversary

and

May you have lots more anniversaries with your PORSCHE

[acapella8]

I will try this in the AM and report back -- watch this space for results!

[PorscheGuy79]

*cough* just go EFI *COUGH!*

[Charlie V]

The AAR is actually a very simple butterfly valve. It basically brings the idle up as the car warms up - like a giant vacuum leak.

Suggest you remove the AAR and bench test it with 12 volts. I used my battery charger. If it closes within 5 to 10 minutes (enough time for a beer), it works. If not, pull it apart (carefully) and bend the bimetal strip (carefully). Bench test again to confirm adjustment. Then put it back in the car to confirm it works.

The removal and installation process while the engine is in the car is a true test of patience. But, it can be done.

I considered replacing mine. Bosch has just stopped making them for my 1982. When I checked, the CDN Bosch distributor said there were 6 left in Germany and the retail list was $1,500 CDN with 6 week delivery. I will not repeat the words I used, but let's just say it encouraged me to "repair" the existing AAR.

[Mysterytrain]

Not sure where this is going. With the AAR plugged you said that the engine idled perfectly. So why did you remove the AAV when it appears to be working properly? Also, I'm not so sure about the statement that some AAR's don't completely close. That wouldn't seem to make much sense. The AAR is an 'automatic' replacement for the hand throttle. It would seem to me that the CIS system would be happiest without that additional unmetered air...which is why the AAV and AAR are designed to be out of the picture after the first few minutes of start up. There are two schools of thought with the CIS components. Some have had great success with removing the AAV and plugging the lines others find they need it. The AAV is providing a big gulp of air while the engine is first cranking and the Cold Start Valve is spraying a lot of fuel. Your airbox might need the AAV more then you do. The AAR again, is nothing more then an electro -mechanical hand throttle. From what you have posted it sounds to me like its the AAR that is leaking.

[Cad.Guy]

What exactly does the AAV ( the saucer thing ) do ?
It seems to just be a open hole from one hose to the other.
Is there something inside that does something ?
I can blow and vacuum it and nothing happens, it is just straight through.

[acapella8]

The AAR is actually a very simple butterfly valve. It basically brings the idle up as the car warms up - like a giant vacuum leak.

[boyt911sc]

Originally Posted by Cad.Guy

What exactly does the AAV ( the saucer thing ) do ?
It seems to just be a open hole from one hose to the other.
Is there something inside that does something ?
I can blow and vacuum it and nothing happens, it is just straight through.

CadGuy,

The AAV (auxiliary air valve) is normally open when engine is not running. What it does is to provide extra gulp of air during a start-up. Once the engine starts to run and produce vacuum, the AAV closes due to the vacuum created by the running motor.

How to test an AAV: Apply vacuum (16” Hg or more) to the outlet tube and the valve will shut closed and hold the vacuum. If it does not hold the vacuum, it means it is leaking and deemed defective.

Tony