AAR Valve
03-01-2006, 06:58 PM
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AAR Valve
In my attempt to resolve the high idle problem on my '79 I am trying to come to grips with my real lack of knowledge on this situation. Responding to the suggestion that I check out the AAR valve I have discovered that I really don't know how to identify the valve. It would appear that my car's actual hose routing must not be in compliance with the service manual diagram for the hose it showed as going to the AAR valve I think goes somewhere else. This is based upon an assumption I came to believe after I viewed a photo of the AAR valve on Pelican Parts web site. Once I saw that picture I belive I identified the AAR valve as sitting just to the right of the IC and having a hose of about six inches length.
I disconnected this hose and plugged it, lacking a plug to stop up the inlet into the IC, I taped over it with some electrical tape, which may have been a mistake. When I started the car there was a pronounced reduction in idle rpm, it initially dropped to about 500 rpm, but shortly came up to about 950-1000. I took the car for a hop to see what effect the disconnect would have and while it did nothing for the rpm's remaining high between shifts it soon made itself apparant in another way. As I approached a stop the car died and would not restart. Upon inspection I determined that my electrical tape "plug" on the inlet to the IC was now missing. I sure hope that it did not get sucked into the IC?
I replaced the hose on the nipple and the car started right up and I drove it home.
To sum it up to this point I have really not accomplished a thing except to maybe reinforce the "a little knowledge is a dangerous thing"? In other words, I have no idea what I am doing. I don't know at this point if I should attempt to remove the IC and get to the "decel" valve or not. I think most of the problems lie with this valve.
Jim Alexander
I disconnected this hose and plugged it, lacking a plug to stop up the inlet into the IC, I taped over it with some electrical tape, which may have been a mistake. When I started the car there was a pronounced reduction in idle rpm, it initially dropped to about 500 rpm, but shortly came up to about 950-1000. I took the car for a hop to see what effect the disconnect would have and while it did nothing for the rpm's remaining high between shifts it soon made itself apparant in another way. As I approached a stop the car died and would not restart. Upon inspection I determined that my electrical tape "plug" on the inlet to the IC was now missing. I sure hope that it did not get sucked into the IC?
I replaced the hose on the nipple and the car started right up and I drove it home.
To sum it up to this point I have really not accomplished a thing except to maybe reinforce the "a little knowledge is a dangerous thing"? In other words, I have no idea what I am doing. I don't know at this point if I should attempt to remove the IC and get to the "decel" valve or not. I think most of the problems lie with this valve.
Jim Alexander
03-01-2006, 07:56 PM
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We all learn from our mistakes.
Hopefully the tape was blown off instead of sucked in. I'm trying to remember if that port you are talking about is on the inlet or outlet side of the I/C. If you pull off the I/C, maybe you can find it in there? Look real carefully around the engine compartment as well. Come to think of it, it may have fallen off and been sucked in by the fan.
To pull the I/C really is easy. Just pay attention to what you loosen and pull off. Label all connections or better yet, take digital pics before and during the process. You can refer back to them as you put it back together if needed.
Hopefully the tape was blown off instead of sucked in. I'm trying to remember if that port you are talking about is on the inlet or outlet side of the I/C. If you pull off the I/C, maybe you can find it in there? Look real carefully around the engine compartment as well. Come to think of it, it may have fallen off and been sucked in by the fan.
To pull the I/C really is easy. Just pay attention to what you loosen and pull off. Label all connections or better yet, take digital pics before and during the process. You can refer back to them as you put it back together if needed.
03-01-2006, 08:03 PM
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That's why you always use a lot of tape instead of a little. And always use duct tape. 
As Rocket has said everyone makes mistakes. If it's leading into the intercooler I doubt it's gone far if it's been sucked in. I'd bet it's probably been blown off though.
I don’t think taking the intercooler off is that large of a job and you certainly will have better access to everything else once that’s done. Also don’t you need to look in there for your tape?
As Rocket has said everyone makes mistakes. If it's leading into the intercooler I doubt it's gone far if it's been sucked in. I'd bet it's probably been blown off though.I don’t think taking the intercooler off is that large of a job and you certainly will have better access to everything else once that’s done. Also don’t you need to look in there for your tape?
03-01-2006, 10:16 PM
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how about this theory.... not quite sure if blown off or sucked in. could think of theory for both. however with it missing you're car was 'breathing' through this hole. if it breathes through this hole at low rpm, then the air is not flowing over the flapper plate. Flapper plate is not getting pushed down at all and putting fuel into car therefor it stalls. after it stalls, you can not start because air flow sensor (that works on flapper motion I believe) does not work, which is required to start fuel pumps.
03-01-2006, 10:32 PM
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AAR Valve
Well, I will probably go ahead and pull the IC if for no other reason than to see if I can find that piece of tape?
Can anyone tell me how I can attach a jpg image to one of these post's? I have taken a digital picture of what I think is the AAR Valve on my car, but heck I'm still not certain?
jim
Can anyone tell me how I can attach a jpg image to one of these post's? I have taken a digital picture of what I think is the AAR Valve on my car, but heck I'm still not certain?
jim
03-01-2006, 11:44 PM
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Cick "Go Advanced" (at the bottom middle of the screen).
After typing your message. Click "Manage Atachments".
Click browse and find on your computer where your pics are. Click on the pic and then click upload. Once it's uploaded, close the box and submit the message.
After typing your message. Click "Manage Atachments".
Click browse and find on your computer where your pics are. Click on the pic and then click upload. Once it's uploaded, close the box and submit the message.
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03-02-2006, 12:56 PM
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Jim,
It's real easy check to see if your AAR is working properly. First, pull of the hose and with a flash light notice there's a little slide door inside it that should be open when the engine is cold. The way it works is there's a bi-metallic spring that when supplied by 12 volts heats up and closes the door, thus, cuting off the "auxillary" air. The way to check it is to pull the two-pin conector and apply 12 volts to the pins of the AAR. Within about 2 minutes the door should slowly close. You may also what to check 12 volts at the two-pin plugs while the engine is running. Good luck!
It's real easy check to see if your AAR is working properly. First, pull of the hose and with a flash light notice there's a little slide door inside it that should be open when the engine is cold. The way it works is there's a bi-metallic spring that when supplied by 12 volts heats up and closes the door, thus, cuting off the "auxillary" air. The way to check it is to pull the two-pin conector and apply 12 volts to the pins of the AAR. Within about 2 minutes the door should slowly close. You may also what to check 12 volts at the two-pin plugs while the engine is running. Good luck!
03-02-2006, 01:07 PM
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Jim,
The photo you sent me does show the hose from the IC to the AAR is attached properly. However, I would recommend you replace the factory hoses(pressure and vacuum) with newer ones. They may not be leaking now, but they are 20 years old.......
I would recommend you remove the IC and the air cleaner to inspect everything. There are two bolts that are on the top of the air cleaner over the metering plate. Not the easiest to get at, but once removed the aircleaner comes out fairly easy. Take some photos of the engine bay and we can talk you through the rest. There may be some binding with the throttle linkage pedestal near the throttle body. I had some problems in that area with my 930. Worth looking at. In my case, one of the springs had broken, which caused a slow throttle return to the stop.
You're right about Porsche boxers vs. Chevy SB's. But if you are mechanically inclined, there is no stopping you. It's a fun engine to work on.
The photo you sent me does show the hose from the IC to the AAR is attached properly. However, I would recommend you replace the factory hoses(pressure and vacuum) with newer ones. They may not be leaking now, but they are 20 years old.......
I would recommend you remove the IC and the air cleaner to inspect everything. There are two bolts that are on the top of the air cleaner over the metering plate. Not the easiest to get at, but once removed the aircleaner comes out fairly easy. Take some photos of the engine bay and we can talk you through the rest. There may be some binding with the throttle linkage pedestal near the throttle body. I had some problems in that area with my 930. Worth looking at. In my case, one of the springs had broken, which caused a slow throttle return to the stop.
You're right about Porsche boxers vs. Chevy SB's. But if you are mechanically inclined, there is no stopping you. It's a fun engine to work on.
03-02-2006, 01:42 PM
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Thanks Guys, with your help I think I can get through this! However, the confusion I am being subjected too is not made any better by the Porsche Service manuals. Last night when I was going throuth the manual attempting to resolve my inability to properly identify the various components of this AAR system I have found several issues that I have still not come to grips with.
To begin with, in the manual there are two separate pages that deal with the Auxillary Air Valve. On page 25-10 there is an item dealing with "Removal and Installing the Auxillary Air Valve" and it shows a photo of the valve. Then on page 25-18 is covers the same issue "Removing and Installing Auxillary Air Valve" and shows a picture of a totally different component. Now move on to page 26-38 "Hose Connection plan - USA - Japan" and it get's real confusing. Here it indicates that a hose runs from the IC to component #5 which is identified as the Auxillary Air Valve (which appears to be the component in the photo on page 25-10 of the manual) and the other hose from the IC runs to component #4, which is here identified as "Throttle bypass valve" (which appears to resemble the component photo on page 25-18 of the service manual, there identified also as the Auxillary Air Valve)
Yikes, no wonder I am confused??
Jim
To begin with, in the manual there are two separate pages that deal with the Auxillary Air Valve. On page 25-10 there is an item dealing with "Removal and Installing the Auxillary Air Valve" and it shows a photo of the valve. Then on page 25-18 is covers the same issue "Removing and Installing Auxillary Air Valve" and shows a picture of a totally different component. Now move on to page 26-38 "Hose Connection plan - USA - Japan" and it get's real confusing. Here it indicates that a hose runs from the IC to component #5 which is identified as the Auxillary Air Valve (which appears to be the component in the photo on page 25-10 of the manual) and the other hose from the IC runs to component #4, which is here identified as "Throttle bypass valve" (which appears to resemble the component photo on page 25-18 of the service manual, there identified also as the Auxillary Air Valve)
Yikes, no wonder I am confused??
Jim
03-02-2006, 06:13 PM
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I didn't get a whole lot accomplished today beyond getting the IC off and removing the Air Cleaner so that I can get at things. However, I did follow JWL's advice and pulled the hose off of the AAR valve and attached a 12v lead to it. The door did slowly close arriving at full closure in the approximately 2 min. he had indicated, so if nothing else does this then eliminate the AAR valve as a source of my problem with the high idle? If so, now what? There had been mention of checking for a vacuum leak, but that obviously is not possible with the IC and AC removed.
Jim
Jim
03-02-2006, 06:15 PM
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OH, I forgot to mention. When examining the engine bay I noticed an Electronic Ignition control box mounted on the inside of the left rear fender. Indicates mfg in Texas, so I assume that I have found a modification to the car involving the addition of electronic ignition?
jim
jim
03-02-2006, 06:53 PM
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Go ahead and replace ALL of the hoses you find under there. My car had th same high idle problem as yours when I bought it... It had like 20 vacuum and boost leaks all caused by old, brittle, out or round, cracked, and dry rotted hoses. I aslo had to replace the seals in the end caps of the boost recirc valve, the seal that goes in between the air meter plate and the plenum, and the waste gate line. You may find your high idle problem will disappear!
E-man930
E-man930
03-02-2006, 07:45 PM
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Originally Posted by jalexand
OH, I forgot to mention. When examining the engine bay I noticed an Electronic Ignition control box mounted on the inside of the left rear fender. Indicates mfg in Texas, so I assume that I have found a modification to the car involving the addition of electronic ignition?
OH, I forgot to mention. When examining the engine bay I noticed an Electronic Ignition control box mounted on the inside of the left rear fender. Indicates mfg in Texas, so I assume that I have found a modification to the car involving the addition of electronic ignition?
Sounds like your AAR is working like it should. Time to do what E-man 930 says and start replacing hoses...it's really a process of elimination.