924Board.org

[kye]

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

[Smoothie]

[Smoothie]

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.
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"..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]

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

[Smoothie]

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]

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]

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]

[teo]

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]

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

[teo]

Ok, I don't really know anything about it, except what I learned from Haynes and from the net, but if it's oily it's dirty on the edges too, and it can be a little sticky on the edges causing it to lift inproperly or a bit later.
Also this is why it only comes in play only at startup and not when it's running.

Anyways, a little cleaning not going to hurt.

[teo]

So I cleaned the plate, it wasn't that dirty than I thought and of course nothing on earth changed. But tightening all the connections at all the rubber parts helped. Oh well, always start with the basics...