Ferrari Mailing List: Re: K-Jetronic continuing story: AAV

[LarryT (l02turner]

Hi Rick -
   I think you'll find (maybe already have) the basic FI system is pretty 
simple.  Like the AAV things are easy to work on and have easily understood 
functions.  I was very hesitant about installing EFI on my 911 until I was 
faced with a box of parts & found them easy to understand.

   I came to admire some of the parts of EFI that performed a function with 
pure simplicity - like the AAV.

   Anyway - spunds like you're well on your way to learning how your system 
was changed and how to fix it.

Good luck - Happy New Year!

Sincerely,
Larry T  (74 911, 91 300D 2.5T)
www.youroil.net Oil Analysis Kits &
Porsche Posters/Weber parts
Test Results - http://members.rennlist.com/oil/

http://www.scamfreetop10.com/1233.html


.
----- Original Message ----- 
From: <rolindsay [at] yahoo.com>
To: "Larry Turner" <l02turner [at] comcast.net>
Cc: "The FerrariList" <ferrari [at] ferrarilist.com>
Sent: Wednesday, December 31, 2008 11:52 AM
Subject: [Ferrari] K-Jetronic continuing story: AAV


> Morning folks,
>
> Continuing the K-Jetronic FI rebuild story; I have removed the auxiliary 
> air valve (AAV) and have cleaned and completed some of the tests. Here is 
> a mini-tutorial and the test results.
>
> The AAV does just what it's name implies. It provides additional air, 
> downstream of the throttle butterfly, to increase cold idle speed. At the 
> same time, the warm-up and control pressure regulator is adding fuel to 
> enrich the idle charge. But that's an other story.
> The AAV is heated by three mechanisms; the engine, an electric heater and 
> the ambient temperature. When the ambient temperature is warm, the AAV is 
> closed. No fast idle is needed. Same is true when the engine is hot. The 
> extra air is needed when its cold and the engine is cold.
> On the 3x8 cars, the AAV is mounted on the engine. On the Mondial, the AAV 
> is bolted to the lower side of the coolant expansion tank. Either way, 
> heat from the running engine causes the valve to close, cutting off the 
> extra air.
> With the ignition on, voltage is applied to a heater coil in the AAV. This 
> coil also causes the valve to heat up and close, even if the coolant 
> temperature hasn't risen high enough yet. Again, fast idle duration is 
> limited.
>
> Okay, it's 57 degrees F outside. The AAV is about 20% open with no current 
> flowing. Removed from the car, I placed the AAV in the freezer for about 
> 10 minutes. No change. Perhaps that wasn't long enough to cause a change? 
> I completed the rest of the tests, described below, then put the unit back 
> in the freezer. I'll check it in about an hour.
> Back on the bench, the heater resistance measures about 45 ohms so 
> continuity is indicated. I applied 12v to the coil and it drew about 260mA 
> of current. If I solve E=IR for E (voltage) I get 11.7 volts. That's close 
> enough to 12 volts so the AAV did not break Ohm's Law!
> Given about a minute, or perhaps a little less, and with voltage applied, 
> the valve had completely closed.  That part is working correctly.
> The final test will be to examine the thoroughly cold unit to see if it is 
> fully open. More on that (and pictures) later.
> If everything tests okay now, the question will remain "Why do I see no 
> increase in warm up idle speed?". Remember, this FI was butchered when the 
> car was 'federalized' so there may even be a plug inserted in the line! 
> Nothing is being assumed to be the way Bosch engineered it.
>
> More after the cold test.
>
> Regards,
>
> Rick
>
> Sent via BlackBerry by AT&T
> _________________________________________________________________
> To unsubscribe or modify your subscription options, please visit:
> http://lists.ferrarilist.com/mailman/options/ferrari/l02turner%40comcast.net
>
> Sponsored by BooyahMedia.com
> and F1 Headlines
> http://www.F1Headlines.com/