Auxiliary air valve, testing etc

So I've been having an ongoing cold idle issue, the revs drop after a couple of minutes gradually to the point it won't idle, just before it cuts out I get a waft of fuel as it struggles then dies. It carries on like this for probably 5 or more minutes at least until it gradually warms up and the revs start to pick up again and when it's warm it idles spot on

Anyway, I've played with a couple of WURs, opened both up cleaned them out put them back together. Still more or less the same, although the spare which didn't work well at all now works better than the one originally on the car. So I'm going to rule that out for now.

So I've turned my attention to the AAV, which I can hear a rush of air through the hose off the inlet to the AAV for the first minuteor two from cold, but if I squeeze it to stop the rush of air nothing happens asides form the rush of air stops. I've read that you squeeze a hose that when cold the revs should drop, but I'm unsure if its the one I'm squeezing or the one from the airbox to the junction on the rocker cover, which does nothing either Anyway. So then I tested the plug with a multimeter with the ignition on and the black grounded to the head, got a reading of 0.01 volts so disconnected the plug whilst running, again no change.

Currently I'm suspecting the electrics at fault (again) but I'm very novice with electrics, to the point I'm not even that confident with doing the testing. So, I plan to remove the AAV and see if it opens and closes but I don't know if it's fused or if it runs off a relay or anything like that I can check first? I imagine the wiring suffers there as it gets a bit hot.

Cheers Kyle.

pretty sure you can just put 12V battery feed to them to test the closing
To check opening put it in the freezer for a couple of hours and see is it fully opens.
I cleaned one up by soaking it in carb cleaner for a few hours and was suprised what came out of it.

good video of testing here:

wanna see an Aux Air Valve at work? (video) - Rennlist - Porsche Discussion Forums


Have a look at your cold start injector also, you can take this out of inlet manifold and place in a jam jar and start the car from cold to see if its spraying for the first few seconds. this is controlled by the Thermo time Switch which would need a test to be sure its sending a signal to the injector when the engine is cold.



 

Thanks for the reply tnotty. Hopefully I'll get around to taking it off and having a look at the weekend, I'd imagine that my symptoms mean that it isn't open/opening, so I'll bung it in the freezer first if it's shut, see if it opens. I've got some Brake cleaner I can have a go at cleaning it out with.

I might try the cold start valve in the morning if I get a chance, pretty sure that'll be a fairly quick thing to try first.

I quite like the soundtrack to the video of it closing, works well 😂

Well I tested the cold start valve, car wouldn't actually fire with it out but there was some fuel in the container when I checked, though it was a bit cloudy. Started fine when reconnected.

I've noticed that as the mornings have got cooler it doesn't actually cut out, the revs do drop considerably though, but finishing work at 4 yesterday was a nightmare, wouldn't idle at all

Have you your AAV in the freezer yet? Left mine in overnight to make sure it is doing what it should and it only opened this much:


If I put 12v across it closes, but I don't know if it should be more open when cold than it currently is.
Car starts OK, but dies after a couple of mins unless I keep some throttle. That said, I'm not sure it's fully set up right yet (seems fine when it is warm). Just wanted a AAV comparison!

I haven't as yet, I hope to take it off and try it today as I've got the day off, although anything can happen with a 3 year old causing chaos!

How do you put 12v across it? I'm clueless with electrics but it's something I'm keen to learn a bit about.

Sounds sort of the same to my symptoms, my idle speed from cold isn't actually much higher than when warm most of the time, it hunts a bit too most mornings before the revs drop off and it'll no longer idle. It's worse on a warm afternoon leaving work, in the mornings it'll just about keep running sometimes but the afternoonis awful. That said I tweaked the idle (on the cable) as it was running about 700 rpm warm and it didn't actually cut out the following day, it wasn't far off mind you.

I have a couple of longish leads made up with small crocodile clips on each end. Like these - https://www.ebay.co.uk/itm/133789018397
You can get made up 'test leads' off ebay, but not sure how long they are.
clip one to each terminal and the other to a battery.

Thanks paceman, I'll get some test leads ordered and try it.

So basically, a funny few days.. was planning to remove AAV Friday, stick it in the freezer and do all that, but my freezer broke instead. Anyway, so I removed it today, tried cleaning it up a bit and left it in some Brake cleaner whilst I did something else and then dried it and put it in the fridge for a few hours. The opening was maybe 3mm x 2mm when I took it off I'd say and It opened hardly anything but I guess it wasn't really in there long enough.

Refitted it, it's not too bad to get at so I can quickly whip it off again at a convenient point. Started the car and unlike before if I squeezed the hose going from cold start valve to AAV it actually bogged down and made a noticeable difference where as before it made no odds. The revs did drop but nothing like they have done, that said it wasn't a particularly hot day which for my car seems to make it worse.

So, I think at least it does look very much like my AAV or the wiring to it is the problem.

On another note I took inlet manifold off and found 2 ports damp and one soaking wet.. I'm guessing bad injectors. Bloody car will be the death of me!

So I finally got around to testing it both for opening and closing,
Got myself some test leads off ebay for about £3 tested it off my battery (which I disconnected first, don't know if I needed to) and it closed fine, I think.

Then I put it in the freezer for probably 2 ish hours, it opened probably about as far as yours paceman. I've got it in some Brake cleaner see if that makes any difference.