justin

Only on cold starts, the car will fire right up, then idle very low and surge idle up too about 1100 rpm, then back down to about 400 rpm,but sometimes it dosnt surge at all, sounds like it wants to die,almost like it's flooding out or running too lean, if I press the gas a little it will either die out or go up and run like poo, then after about 30-60 seconds of feathering the gas it will clear up and be ok. Jim Bailey @ 928intl told me to unplug the cold start valve to see if it made a difference, I did and no difference, besides not wanting to start when cold, till I cranked it a few times. I looked at the aux. air valve to see what it was doing, I unplugged the electrical connector, and stuck a small screw driver in the hole when the engine is cold and it was closed. Does it need to be plugged in and the key on to check this?
TIA

justin

I plugged the aux air valve back in and turned the key on, re-checked and it is still closed. Is this my problem?
TIA

Mongo

Needs an air valve me thinks.

justin

Is The Stig right? I nned to get this fixed ASAP.
TIA

Rod Underwood

The Auxilary Air Valve on the 82 has a bimetalic strip in it that will change over a minute or two. It is not like my 87 where it switches open or closed. I have the same problem and have been able to make it a bit better, but not get rid of it yet. I switched out the idle micro switch and the full throttle micro switch and that also helped a bit, but still....

This thread has what a couple of us have tried.
https://rennlist.com/forums/928-forum/259174-82-auxiliary-air-regulator-and-other-stuff.html

If you find a solution, let me know.

Dennis Wilson

The AAV opens a little or a lot dependant upon the air temps and the internal heater. Unless it was really cold, I doubt that it would be open enough to feel with a screwdriver. Either use a mirror and a flashlight to check for actual opening or remove it, place it in the fridge then check it. If it stays completely closed even when refrigerated it needs adjusted, rebuilt or replaced. IIRC there was a thread about a month ago on adjusting the AAV.

Dennis

justin

It was about 75 - 80 degrees here last night, it was fully closed, I will double check it though.

jpitman2

Mine was ~30% open at 28F from the freezer. Never did have a fast idle on cold start, but rarely died during warmup until lately (fall here now). I opened it up, gradually stretched/softened the spring pulling it shut until at 28F it was nearer 80% open. Then applied 12V to contacts, and after 3-4 mins it was 99% shut. Fist cold start at ~ 60F ambient gave me 1200rpm, which I have never seen before. Also I note that the body casting has an arrow on top, which usually indicates air flow direction, but in all the 928s I have seen air flows the OPPOSITE direction? If air flowed in correct direction the suction would tend to hold the valve plate firm against a flat surface on the body, and seal it well, but in opposite direction it wont seal at all well IMHO....comments Dennis?
jp 83 Euro S AT CIS 50k

Dennis Wilson

It should start partially opening below 100F.

Dennis

Dennis Wilson

Jay,

The air should flow from the filter side of the throttlebody to the head side. The arrow on mine is correct in that the inlet is from below the throttle body and outlet goes to the upper plenum by the cold start valve. Considering that the valve uses a rotary plate and you want suction to seal the port when the engine is warm, the arrow should be in the direction of the air flow.

Your adjustment sounds correct since 30% at 28F is too low. If the spring is linear (should be) the gate should have been nearly 70% open at 28F.

Dennis

justin

So its about 85 - 90 degree's here now, what should I find if I look at it, opened or closed, I havnt started the car all day.

Dennis Wilson

Look for a small/narrow cresent shaped opening. BTW it is nearly that warm here in OK.

Dennis

ViribusUnits

I wouldn't expect the AAV to cause your surgeing. I would think it might cause a low or fast idle, but I don't think it would cause a surgeing. It might cause an idle that is so slow in cold weather that really doesn't want to start at all. I don't belive the AAV does much at all in most Texas weather, even in the Winter.

Even if it was causeing problem, if you open the throtal, the engine should nearly innore the AAV, and roar to life.

I would bet more on a vacuum leak to cause surgeing. That or a bad Temp II, AFM, or grounds (most specificly the one on the intake mannafold), or the infamous green wire.

justin

Ok I took it off the car and it was almost half way opened, is this normal?

Dennis Wilson

At 85F that is open too far. Does it move when the AAV is rotated?

Dennis