924Board.org

Smoothie · Posted: Tue Jun 01, 2004 10:38 am Post subject:

I had another look at my AAV today and it all came back -
Looking at the long squarish part of the AAV you should see on one side toward the end, a round plug/cover and on the opposite side, a smaller round recessed piece. The smaller round piece is the end of a rod and the bi-metal bar assembly inside is mounted to it. Adjusting involves driving that rod in or out. Looking at the end of the rod at this point, if you were to drive it inward, that would be closing the air passage more. If you want to have the air passage opened more, the plug/cover has to be driven out the other side, then the rod driven back from there, but before you do anything, get a measurement of how far down the rod is located in case you want to put it back the way it was, later. Anyway, to have the passage opened more, the larger plug/cover has to be removed. That's done by driving in the rod from the other side to its' limit of travel. Once that's done, the plug/cover will be sticking out about 6-7mm. You have to remove it the rest of the way however you can, but carefully because it forms a leak proof seal (to prevent a vacuum leak). Once that plug/cover is off, you'll see the end of the stud that goes into the several times previously mentioned rod. So, to have the air passage more open at cold startup, drive the rod in by the end of the stud. To have it more closed, drive the rod in from the other side (the flat, normally exposed end of the rod).

-But before you bother with any of that, have a look at the air passage opening - should be -roughly- 1/4 open at room temp. Then throw it into a freezer for 15 min. and look again - should be maybe 1/2 open (I'm judging by what mine did in a freezer that's set to about 10*F (-12*C)

) Then hook it up to 12v power and see that it closes - mine took 10 minutes to close completely. If it doesn't open/close as it should, remove the 4 screws and have a look inside. The spring-loaded plate with the odd-shaped hole cutout should rotate easily on its' pivot by finger pressure and return when you release it.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Smoothie · Posted: Tue Jun 01, 2004 2:21 pm Post subject:

Driving the rod in. This part of the procedure looks the same whether you're just moving the rod slightly to adjust the air passage to be more closed or you're driving the plug/seal out the opposite side.

The plug/seal after being driven out ~6-7mm - needs to be carefully removed from this point so as not to mess up the seal it provides.

Driving the rod back the opposite way by the stud&nut end. This is the way to go to open the air passage more -

Interior view with the rod driven fully in by the flat, exposed end.
In this position the air passage would be less open at startup and would close sooner on warmup.

Here, the rod was driven fully in the opposite direction (by the stud&nut end).
In this position the air passage would be more open at startup and would stay open longer during warmup.

Checking the rods' depth. The reading taken previously and being shown here is 0.15" (3.8mm). I later adjusted it to 0.10" (2.5mm) to have it opened a little more, hoping this will take care of an occasional problem with stalling during warmup in cold weather.

Quick summary of moving parts -

Reassembly -
Make sure the side of the bi-metal bar and the "tab" on the rotating plate meet up..

...which should leave it at a position similar to this -

....then rotate it to line up the screw holes -

_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

kye · Posted: Wed Jun 02, 2004 11:24 am Post subject:

thanks for that smoothie, that's a huge help.
i'm familiar with adjusting things (computers, audio gear, etc..) but the adjustments on cars seem to be very different. so different that I don't even see them!
the pin on mine appears to be pushed in a fair bit, which would explain why it's quite closed. i'll knock it out and push it back a ways and then adjust it to taste.

mine doesn't have screws to open the unit, they appear to be pins, but that's a side issue as I can still adjust it and see the gap without opening it..

thanks again!

you guys rock

_________________
it's funny, but when they said "Anything is Possible", that's exactly what they meant....

Roger · Joined: 06 Jan 2003 Posts: 1235 Location: Cordova, TN

Smoothie
Mine looks much different, perhaps the part changed in 82.

Kye
I belive that the pins you refer to are rivets. You can drill them out and sinply buy a rivet gun at the local hardware store to replace them.
_________________
1981 924 NA

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.

Smoothie · Posted: Wed Jun 02, 2004 1:09 pm Post subject:

Cool

kye · Posted: Thu Jun 03, 2004 11:27 am Post subject:

mine looks the same as smoothies roger, and i've got the 81 931 UK model.. maybe it's different on the turbo?

I adjusted it last night (at one point after hammering for about 30 seconds I considered the neighbours sanity - they're hard to get out!) and the car was a bit better for it.
I still think it could go up a bit more, but i'll play with it.

the symptoms are that if you try to start it, and it fails the first time (or you stall it like me) then it's very difficult to get going again. i'm going to replace spark leads and such to eliminate weak spark with it, but it seems that the regulator can only hold the car going once it's been running for about 30-60 seconds.
is that normal? or do I just need to up the warm idle speed a lot more?
_________________
it's funny, but when they said "Anything is Possible", that's exactly what they meant....

Smoothie · Posted: Thu Jun 03, 2004 1:41 pm Post subject:

Smoothie · Posted: Fri Jun 04, 2004 1:41 am Post subject:

But then again, on ponderin' the situation further... (exactly 12 hours later

)
The difficult starting second time around could be and probably is due to the fact that the cold start injector isn't getting activated again, so actually the problem is not enough, rather than too much fuel. I used to think that it was getting flooded, and found that after letting it sit a minute with the ignition switched off, the flooding was cleared enough to allow it to start again. -But, now I'm thinking that after the thermo time switch has time to reset (cool down and close its' contacts again), it's ready to give another shot from the cold start injector, making starting easier again.
-So, I'd like to change that guess from "flooding" to "lack of cold start injection" as the reason for the tough start second time 'round.

Either way you think of it though, the solution is to let it sit a minute between tries.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

kye · Posted: Fri Jun 04, 2004 5:27 pm Post subject:

on the second go, if you started it with your foot flat to the boards, would that simulate the cold start injector? or do the normal injectors act differently?
it seems that the longer you wait before having another go, the more firing you get when first turn it over. it reaches a point where it just turns and doesn't fire (thus, me thinking it was flooded). i've tried putting my foot down at that point but it didn't acheive anything.

a friend of mine said that because the intake is cool, the fuel condenses and isn't as useful..
I had thoughts about a small gas torch you could fire up and warm up whatever the bit is that needs warming up!
I wouldn't be game to try it, but it's an amusing idea.

_________________
it's funny, but when they said "Anything is Possible", that's exactly what they meant....

Smoothie · Posted: Sat Jun 05, 2004 3:18 am Post subject:

Here's what happens with mine (I started it today without touching the gas pedal and noted what happened and when) -
Turned the key, it starts right up and runs good for ~10 seconds (about the time the cold start injector should be switching off), then the idle speed dips and dips some more 'til it starts to stumble, then picks itself up again, dips and stumbles again... To keep it from doing the dips and stumbles I can blip the throttle* a few times as it begins to happen to pick up the engine speed and keep it going. If on the other hand, I just press the pedal to the floor and hold it there when it's starting to stumble, it tends to stall out. I think that even though my cold start valve and thermo time switch are apparently operating as they should, I could still benefit from the addition of the switch that manually operates the cold start valve. Not really necessary since I know how to keep it running by blipping the throttle, but it could be used just as a convenience.

*- probably safe to assume that blipping the throttle gives it an extra shot of fuel just as a carbureted engine gets from the fuel enrichment pump (or whatever its' called) that's built into a carburetor, but I'll have to read up on that and how it's done in CIS to be at all conversant in it. -But assuming it does get an extra shot of fuel each time I hit the pedal, that means it's more fuel that's keeping it running. If you just hit the pedal once and press it to the floor, that's of course only one shot of fuel.
Long story short - I'm still thinking the problem relates to not enough fuel rather than too much. Actually real sure of it in my case and if blipping the throttle helps yours to start, real sure the same's happening to you.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Smoothie · Posted: Sat Jun 05, 2004 6:45 am Post subject:

I did a little reading of "Bosch Fuel Injection & Engine Management" by Charles Probst. Good book. Recommended reading. I should read it more often myself.

kye · Posted: Sat Jun 05, 2004 11:29 pm Post subject:

it's interesting that you've said that when the revs start to fall that flooring it stalls it but no throttle lets it recover, mine is the other way around!
i'm not sure about starting it without throttle, but once it's going it will run smoothly at 1100+RPM, but anything below that point and it will stutter and die - I have to manually keep it above that point by using the throttle to pick the revs up again. once it dips below the ~800-1000RPM mark it starts missing and spluttering, and isn't quick to respond to more throttle, but with full throttle it will recover from less than 400RPM and avoid stalling.
so yes, lack of fuel due to condensation seems to be the culprit.

other things i'm pursuing is i've got a new coil, dizzy, and leads on order, and I got new plugs about a month ago, so they'll all be new, and i'm pretty sure the place I got it serviced would have only done a static tune, so i'll consider at getting it dyno'd and possibly re-curved as well.
i'm going to have another go at opening the aux air regulator a bit more too. it's about a third open when cold, but i'll play with it more.

if problems pursist, i'll be looking further (perhaps at the fuel system) but i'm hoping the new electrics will make it a bit smoother. replacing the thin hoses (that were pretty much rock solid) in the pressurised zone (vacuum/boost) made it a lot nicer too, and the replacement was just a hack job - i've got some fuel line and hose clamps waiting there for me to do it properly.
_________________
it's funny, but when they said "Anything is Possible", that's exactly what they meant....

Smoothie · Posted: Sun Jun 06, 2004 4:35 am Post subject:

teo · Joined: 07 Sep 2001 Posts: 637 Location: Hungary, Europe

Smoothie,

mine ('80 924) has the same starting symptoms as yours, and I know the air metering plate has some deposit (some oily stuff) on it.

Now as you said

Smoothie · Posted: Tue Jun 08, 2004 2:52 am Post subject:

Thanks Teo.
Actually my air metering plate goes the other way as on all 931s (down), so a little dirt [might actually help?]. Shouldn't be an issue either way, but the plate on mine's already clean. Actually the inertia there is inherent in any car with the fuel distributor and air-metering plate arrangement. A little bit of it would be due to the simple physics - an object at rest tending to stay at rest, etc. and more of it due to fuel back pressure on the rod at center of the fuel dist - that back pressure has to be overcome by the force of the air moving the plate and rod. It's nothing that needs or even can be fixed - just a fact of life for K-Jetronic.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox