Auxiliary Air Valve Question
06-02-2014, 05:32 PM
#1
Three Wheelin'
Thread Starter
Auxiliary Air Valve Question
I posted this question as part of another thread but figured I would start a new post as no one has replied to my question yet -
Does any know if a malfunctioning Auxiliary Air Valve would cause a lean condition, or could it cause a high idle? It seems to me that this is metered air as the supply comes after the MAF so I don't think it would cause a lean AFR, however, I removed the AAV and popped it in the freezer for an hour and based on some photos and a "Space Odyssey" video here on RL it opened fully. Then I put it in the oven on 210 degrees for an hour but it never fully closed, there was still a small slot that remained open. I'm not sure if this is normal or not or if it would even affect the idle? I've searched and found that people have taken these apart and modifies the bi-metal strip but I'm wondering if this is working well enough that I shouldn't screw with it? Any thoughts?
Does any know if a malfunctioning Auxiliary Air Valve would cause a lean condition, or could it cause a high idle? It seems to me that this is metered air as the supply comes after the MAF so I don't think it would cause a lean AFR, however, I removed the AAV and popped it in the freezer for an hour and based on some photos and a "Space Odyssey" video here on RL it opened fully. Then I put it in the oven on 210 degrees for an hour but it never fully closed, there was still a small slot that remained open. I'm not sure if this is normal or not or if it would even affect the idle? I've searched and found that people have taken these apart and modifies the bi-metal strip but I'm wondering if this is working well enough that I shouldn't screw with it? Any thoughts?
06-02-2014, 08:30 PM
#3
Former Sponsor
Try some more reasonable temperatures and see how it works.....say 60 degrees and 120 degrees.
06-03-2014, 04:50 PM
#5
Three Wheelin'
Thread Starter
Thanks for the input. I think I'll pull it again, test it at reasonable temps to get a bench mark, and then take it apart and try to get it to fully close at operating temps.
06-03-2014, 09:20 PM
#6
Basic Sponsor
Rennlist
Site Sponsor
Rennlist
Site Sponsor
The heat is applied by the heating strip - short term - not the engine temperature so check the strip is getting power and doing its job of closing the disc. IIRC the disc never closes 100%. Linked to the thermal time switch on the early cars but where it gets its signal on the S2 cars I don't know.
Caveat - I am just a parts salesman so double check what I say with someone like Greg 8>)
Caveat - I am just a parts salesman so double check what I say with someone like Greg 8>)
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
06-05-2014, 07:50 AM
#7
Three Wheelin'
Thread Starter
Just to close this out.
It turns out my problem with idle was caused by the adjustable fuel pressure regulator and not the AAR. The AFPR was only 8 months old but it had a small vacuum leak where it would drop about a pound of vacuum in 30 seconds. I replaced the bladder and all is well, for now. Thanks for everyone's input.
It turns out my problem with idle was caused by the adjustable fuel pressure regulator and not the AAR. The AFPR was only 8 months old but it had a small vacuum leak where it would drop about a pound of vacuum in 30 seconds. I replaced the bladder and all is well, for now. Thanks for everyone's input.
