Auxilary Air Regulator and Valve.

BeeBeeper · 01-19-2005, 06:06 PM

I have a 1982 SC that starts up fine and runs around 2,000 RPM's which I know is high for about a minute or less , then the engine RPM's drop to 400 and starts choking, back-firing, etc. When I crank it up I usuaslly get the car going right away so it is not idling at that speed. The RPM drop is the killer for me. I have had this car for about a year and it has happen since I had the car, except it is getting worst.

Once the engine warms up , it seems to run okay.

I have gone through the distributor for corrosion and weights, checked the warm up regulator pressure, check the 02 sensor, and these seem to be okay. I just had the engine taken out and changed all the boots for intake manifolds and every rubber gasket on the car and am convinced I have no vacuum leaks.

My friend who is a lot more savy around Porsches than I think it is the auxilllary Air Regulator and Valve.

Any ideas on this and how can I check this out. Is there a procedure??

Does anyone have a used one that they are willing to part with, especilly if someone changed to webers or Solex carberators and don't need this on their CIS system.

Any help out there would be appreciated.

Ron

BeeBeeper · 01-19-2005, 07:25 PM

While searching around the interent I found a diagnostic CIS site through Renlist. Anyone having a problem with cold starts, rough idles, etc could go to this site as a start to find some possible solutions to your problems.

I haven't spent much time at the site , but looks interesting.

http://members.rennlist.com/jimwms/CIS/CIShome.html

Ron

clevy70911T · clevy70911T's Garage

When I had idle problems, part of my diagnostics were to isolate the different parts of the CIS system out of the air-flow circuit. By taking off a hose clamp, inserting some kind of plug( duct tape diaphram in my case), putting back on the hose to block the air from traveling through that part. This applies to AAR, AAV, or decel valve. By doing this to each part, I was able to find where my high idle was coming from. Eventually, I kept the AAV and decel valve plugged and will soon take out completely.
In your case, sounds like the AAR works and closes fast, perhaps too fast. Also could be CIS fuel pressure problem or a mixture problem.
If all of your fuel pressures are in spec and the frequency valve is working, you've narrowed it down some. You might have to watch the AAR close with a mirror or take it out and test it.

My constantly changing order for checking the CIS.

1 Obvious vaccuum leaks or etc.
2 Frequency valve buzzing?
3 CIS fuel pressures in check
4 Isolate AAR, AAV, decel valve one at a time.
5 A/F mixture check

Hope this helps a little.

BeeBeeper · 01-20-2005, 09:29 PM

Scott,

Thanks for your advice.
So far I check everywhere and find no vacuum leaks. I just pulled the engine to put the hydraulic tensionsers and changed all the intake manifold boots, the injections sytem and changed every gasket you can think of. I took out the warm up regualtor and the pressure is okay, including the ohms which fit within the specs. The injectors are okay. I am starting to work toward the passenger side of the engine.

Tonight I took a mirror and saw that the AAR valve is half open when I would start the car cold. I checked the ohms and find 35 which I saw on a post this about spec also. I was going to take it out tonight , however I did not feel like taking out my A/C to get to the bolt that holds the AAR valve to the engine. In case something got stuck I poured some wd-40 in there and will leave overnight and see if that helps. Maybe it is sticky in there. One post I read last night had one inovative individual drill out the four bolts holding the AAR plates together and he changed the wrapping on the heat plate to show more resistance and his cars works well now on cold start. If I isolate it to the AAR, I will have nothing to lose.

I don't know who the engineer was that put that bolt under manifold. Maybe he wasn't cuddled when he was young.

Fuel pressures are good. Also my mixtures are within spec and have analyzed the exhaust with the car warm so I know my settings there are okay. Infact the car runs like a bat out of hell when she is warm.

MY next step is to work the AAR, AAV, decel valve one at a time as you sggested.

Where is the frequency valve???

Thanks for your help.

Ron

clevy70911T · clevy70911T's Garage

Frequency valve is behind the throttle body, down low and a bosch connector to it. It buzzes when the engine runs and makes fine mixture adustments from the O2 sensor and brain under the pass seat. If it runs good warm, I dont think there is a problem with the freq valve.
I took my AAR apart and modified it to be open 1/3 when cold and close completely when warm. Where does your car idle when completely warmed up? If it still is too low when completely warm and all the other things check out, you might just crack open the idle screw alittle.
Still sounds like the AAR is closing too soon before the car is warm enough to idle regular. But it also sounds lean at that stage causing the poor running and that means false air/leaks.
Hopefully someone else will jump in and give more ideas.

Elombard · 01-21-2005, 03:56 AM

You can check the AAR in place. Put 12 volts to it from a battery or I used a charger and watch with the mirror. It should close up over a couple of minutes. The AAV is another matter, my car is stripper and i cant get it out. I would do as suggested. Pull the hoses from the back of the boot (boot from Throttle body to mixyture plunger deal) and plug them and see if it effects running. The decel valve is very easy to check, all that can go wrong is a leak in the diaphragm. With car running start pulling hoses and you can determine if the diaphragm has a leak by plugging various hoses and ports with your fingers. Some of the hoses are above the diaphragm and some are below and you can see how the car running changes with and with out a vacuum leak. Sorry thats not very clear.

Mysterytrain · 01-21-2005, 05:58 AM

If the AAV is not closing then you would have a high idle condition. I had the same type of problem with the AAR on my 78SC. The car would start right up. to the fast idle, then drop down to about 1K for 2 mins after which it would idle at about 700 rpm or so and stall at every stop sign until the car warmed up. Do a search on my thread... 'AAR revisted '
If your AAR is reading 33 ohms or so and closing completely in 5 mins or so I think you should look elsewhere. Are you sure you have 12 volts going to the heating element on the Warmup regulator. That coil is leaning things out while the is warming up. Once the engine is hot the body of the WUR has now soaked up heat and the spring is taking over the pressures.

Paulporsche · 01-23-2005, 09:30 AM

Ron,

You said your fuel pressures are good. Did you include a check on your cold control pressure? When warm, what is your idle speed?

955i911sc · 01-23-2005, 09:54 AM

I agree, warm cold control pressures are critical, I aways shoot for the high side of the system pressure spec and the low side of the control pressure spec.... make sure your at rest sensor plate height adjustment is good, when checking /adjusting mixture make sure you are not adjusting with charcoal canister HC incoming... you only care about the real fuel air mix as from ambient air and the injectors, prevent emissions system impact on the mix when adjusting.... maybe the charcol can is saturated?

Sounds like you have covered the possiblities well, in the past I have found a high buildup of carbon on the back of the intake valves to be the cause of the symptoms you describe. Evenm thought the idle has fallen to warm spec and the fule control pressure is by now dominate, the enging is not quite up to operating temperature. The carbon acts like a sponge absorbing the richer mixture intended for the cylinder.

This is more noticable on CIS systems where the fuel waits behind the intake valve for its turn to mix with the air charge... air leaks can be sneaky...

BeeBeeper · 01-24-2005, 07:24 AM

Scott, EW, Paul & Mystery Train,

Thanks for all the good advice. I planned on working ont he car this past weekend, however with temperatures at 29 degrees(usual for Louisisana), I decided to wait until it warmed up a little.

I drove the car hoewver over the weekend and these were the symptoms:

Started right up at a high RPM of around 2,000 +

I started driving immediately and let her warm up , however it took
a long time for her to warm up.

When I would stop at a light the RPM/'s would drop to 400- 600
RPM's and would choke and pop like crazy. Hard to ger her
going again.

After the car reaches the first bar on the temperature guage the
car runs very well.

I will test all the suggestions you have made and let you know how things work out. Thanks again for your help. This forum is a very informative and helpful site.

Ron

Paulporsche · 01-24-2005, 07:55 AM

Regarding vacuum leaks: try checking your decel valve.

My guess, though, is the WUR. Did you get the correct cold control pressure?

You may get lucky and your mixture may just be set too lean. Can you enrichen it without causing a hunting idle?

In the present condition, does your warm idle speed go to about 950?

Elombard · 01-24-2005, 08:01 AM

Yah I am thinking vltage at the WUR??

stlrj · 01-24-2005, 03:28 PM

Do you have a pop off valve? If so is it fully seated? Your air box might be cracked too.

-Joe

BeeBeeper · 01-24-2005, 05:59 PM

This evening , I checked the voltage to the WUR and got 12volts. The ohms of resistance of the WUR is 26.

The ohms of resistance of the AAR is 35.
I disconnected the hose on right side of the AAR and the car will not run without it connected. I plugged the hose on the right side and get about the same results(not running well when cold)

I got 12 volts at the CO2 connector under the passager seat on pole 30.

Someone mentioned the frequency valve. I have a modified exhaust system and cannot hear any buzzing maybe because my pipes are too loud.

Can you hear the frequency valve buzzing with just the key turned on?? and the engine not running??? If this is so I get no sound or buzzing when I turn on the key.

I am still working my way through the rest.

Thanks for your suggestions. I know this is a solvable problem.
The car runs so well when it is warm. I have not tried to blow in it's ear yet. Maybe that would work!!

Thanks again!!

Ron

BeeBeeper · 01-24-2005, 06:12 PM

Here are a few pictures. One when I changed the tensioner with the engine out and another one in the driveway.

I do have a pop off valve and checked it with carberator spray and pressed down on it hard with no results. I don't hink I have a leak there, however good suggestion.

Elombard · 01-25-2005, 04:03 AM

DId you try pulling the lines off the decel valve to prove the diaphragm is intact? Probably not the problem as that would show al the time.

Try pulling the hoses at the back of the intake boot (looks like a turtle). That way you isolate the AAR and all possible hose leaks in that system.

I would post your control pressures as the car warms. Let everyone see what the pressures do over time (like 10 minutes). That way some of the experts here can see how your WUR is working as the bimetal strip heats.

Another long shot did you check your pressure and volume from your fuel pump? Its pretty easy. Also does the car hold pressure after its shut off. I had a hole in the diapragm in my fuel accumulator and it did some weird things.

Try this unplug the AAV (voltage) and see how it runs.

Fun free stuff to try!!!

clevy70911T · clevy70911T's Garage

To hear the frequency valve running with the car off, you can unplug the bosch connector to the back of the airflow plate housing and turn the key on.

or

Just turn on the key and lift the air sensor plate to get the fuel pump/FV running. Not to long as you are injecting fuel into the intakes.

If you dont hear it buzzing now, it is not working.

Quote:

Originally posted by BeeBeeper
This evening , I checked the voltage to the WUR and got 12volts. The ohms of resistance of the WUR is 26.

The ohms of resistance of the AAR is 35.
I disconnected the hose on right side of the AAR and the car will not run without it connected. I plugged the hose on the right side and get about the same results(not running well when cold)

I got 12 volts at the CO2 connector under the passager seat on pole 30.

Someone mentioned the frequency valve. I have a modified exhaust system and cannot hear any buzzing maybe because my pipes are too loud.

Can you hear the frequency valve buzzing with just the key turned on?? and the engine not running??? If this is so I get no sound or buzzing when I turn on the key.

I am still working my way through the rest.

Thanks for your suggestions. I know this is a solvable problem.
The car runs so well when it is warm. I have not tried to blow in it's ear yet. Maybe that would work!!

Thanks again!!

Ron

SC-targa · 01-25-2005, 07:28 AM

Ron,

That's a beautiful car. I love the color and the BBS wheels. Sounds like a maddening problem. Hang in there.

Why does your car have a Cab motor mount system?

Regards,

Jerry Kroeger

BeeBeeper · 01-25-2005, 07:40 AM

Thanks for all the suggestions. By this weekend I should be able to go through the car and check all the things you suggested.

I will run all the pressures, ohms and voltage and post so the experts can give me some of their thoughts.

The motor mount system was the way it is when I purchased the car. I bought it when it had 46K and now has 55k original miles. I know the car sat up for about 4 years in a warehouse. For this reason I have changed a lot of parts, especially rubber parts over the past 18 months.

Thanks,

Ron