| athorp |
Posted
Thursday, Apr 29th 3:56am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 14
MN, USA
1979 323i, 1990 325i, 2002 540i |
In conjunction with my timing belt change, I'm changing all the vacuum lines on my 1979 323i.
The hoses to the auxillary air valve were shredded at the attatchment to the valve so I'm thinking that is the source of the vacuum leak that I have long suspected but have never been able to localize.
As I try to learn more about the auxillary air valve I read that it should close after the engine runs about 5 minutes. Now I am wondering if that is why my car idles fast (12-14,000) at first but then sometimes increases to 22,000 after several minutes.
How do you tell if the aux air valve is getting electricity?
How can you tell if the valve actually closes? To see the aperture you would have to remove the valve and undo the hoses and I'm not sure if the car would run under those conditions.
|
 |
|
| bimmer79 |
Posted
Thursday, Apr 29th 6:03am [Edit] [Quote] [IMS] [View car] |
Junior Member
Post nr. 3
|
I learned one trick to check that aux air valve. It should be wide open when it's cold, so put it in your freezer for about 45 minutes. When you check it, it should be wide open. I think there is no electricity at the plug, the aux air valve recieves electrical impulses via the thermo time switch. I think I'm right, can anybody add anything else?
Good luck,
Daniel |
|
|
| melloh |
Posted
Thursday, Apr 29th 8:21am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 160
California, USA (San Jose)
1980 320is, 1991 318is |
I'm not sure abt the electricity part, but Haynes also suggests boiling it in water. It should be closed when @ temperature (can't see through it). It's been said that if this open/close action is not working very well, dousing it in wd40 (or similar) and shaking it like a 007 martini can clean it so that the filament can slide. It's an easy, cheap, thing to try b4 doing anything else. It worked for me.
EDIT: Oops... I'm thinking of the cold start valve. Is that the same thing? I forgot....... Sorry, it's past my bedtime again. |
|
|
| Tricord |
Posted
Thursday, Apr 29th 11:52am [Edit] [Quote] [IMS] [View car] |
Administrator
Post nr. 509
Belgium, Europe
323i Baur |
Yeah it's the same thing.
Anyway, if the valve is stuck open in the car it's easy to identify (I've had it). The car starts fine, and the idle rises as the temperature rises. When the car is hot you have a 1800-2200rpm idle which there is no way getting lower.
I tested just to be sure by putting a garden hose tap on the vacuum line that goes to the valve, like so:
When the engine was hot, I would close the tap and the idle would lower to it's usual ~800rpm. |
|
|
| RDAvena |
Posted
Thursday, Apr 29th 5:19pm [Edit] [Quote] [IMS] [View car] |
Staff
Post nr. 514
SELECT * FROM users WHERE clue > 0
1981 323i, 1988 545is, 1997 528i |
just did this on the 545i. Put it in the freezer and it should be wide open. Put it in a 170 degree oven for a few and it should be closed. If either fails you have a faulty part.
No cleaning in the world will fix a broken one but it will help one that works. Use carb cleaner since most of the stuff in there is crankcase ventilation deposits.
22,000? you have an F1 engine in that e21  |
|
|
| Atle |
Posted
Thursday, Apr 29th 6:48pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 15
Norway
Bmw 320/6 82 Bmw 323i 79, Bmw 323i 82 Bmw e30 320i cab 88 |
The auxillary air valve har to different ways in opening/closing.
Nr 1: There is a bi metal strip inside which opens and closes the air valve in relation to the temperature outside the valve. At -30 degrees the valve should be fully open. At +20 degrees the valve should be partially closed.
Nr 2 :There is an eletrick heater element inside the valve. The current feed to the valve heats ut the element, making the bi metal strip to close the air slide
How to check the air valve
The engine should be cold.
1. Pull out you fuel pump relay.
Disconnect the rubber hoses to the valve to be able to see trough it
Disconnect the eletrik cable to the valve
Connect a volt meter to the two pins.
Make a jump lead between 30 and and 87b (87)in the fuel pump relay socket.
Turn on the ignition. You fuel pump will start to pump. You should now have 12v at you volt meter.
Connect the eletrik plug to you valve again. See trough the valve. The current is now flowing through the element cousing the bi metal strip to get hotter. The air slide should now be slowly closing. When it hot there should remain a small hole trough the air slide. (Use must have your jump lead at the fuel pump relay socket still connected.)
If the air slide does not close now you should mesure the resistant in the heater element. To do that disconnect the eletrik plug at the valve. Connect an ohm meter to the valve. You should find resistant. If not the heating element is broken, and you need a new air valve. |
|
|
| Tricord |
Posted
Thursday, Apr 29th 6:59pm [Edit] [Quote] [IMS] [View car] |
Administrator
Post nr. 512
Belgium, Europe
323i Baur |
Atle, some of them were only water-heated and have no electric contacts... |
|
|
| Atle |
Posted
Thursday, Apr 29th 7:19pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 16
Norway
Bmw 320/6 82 Bmw 323i 79, Bmw 323i 82 Bmw e30 320i cab 88 |
Yes you are right Tricord. Then the water heats up the valve insted of the eletric heater element.
Reading for "athorp" 's first post it seems like he have an eletrik contakt. Anyone know when they changed the air valve? At least with the eletrick operated valve you have a couple of hoses less under the hood.  |
|
|
| athorp |
Posted
Thursday, Apr 29th 11:38pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 15
MN, USA
1979 323i, 1990 325i, 2002 540i |
Mine does have the electrical connection.
So does the aperture close based on ambient temperature or because of a signal from somewhere via the electrical connector? |
|
|
| Atle |
Posted
Friday, Apr 30th 12:02am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 17
Norway
Bmw 320/6 82 Bmw 323i 79, Bmw 323i 82 Bmw e30 320i cab 88 |
The air slide close when the valve is heated up. The current feed into the air valve goes into a heating element. This is cousing the bi metal strip to close the air slide.
When its hot outside you air valve would be almost closed before you start up you car.
When its cold outside your air slide will be open. When you start your car, the air valve starts to heat up, cousing the passage in the air slide to become smaller.
The main object of the air slide is to provide additonal air to the engine when it's cold. Therefore the passage when the engine is cold is large and the passage in the air valve when your engine is hot is small, allowing less air to the engine.
the air valve is a very simple way to raise the idle speed of the engine when its cold.
So, the bi metal strip (formed as a spring) contrakt and expand with the temperature. At the end of the spring the air valve is connected. The air slide will then open and close when the spring contrakt and expand.
So, if your heating element inside the air valve is broken it will take much longer time for the air slide to close on a cold day, because it then has to be heated up by the hot air from the engine. This may not be enough to close the air slide propperly, and you will end up with an high idle speed. |
|
|
| Atle |
Posted
Friday, Apr 30th 12:08am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 18
Norway
Bmw 320/6 82 Bmw 323i 79, Bmw 323i 82 Bmw e30 320i cab 88 |
The current to the air valve is feed from the fuel pump relay. Is connected to the same output as you fuel pump 87(b). This means that as long as your fuel pump is pumping you will find 12 v at your air valve |
|
|
| athorp |
Posted
Friday, Apr 30th 1:18am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 16
MN, USA
1979 323i, 1990 325i, 2002 540i |
Thanks for the information Atle.
If I'm understanding correctly, when the fuel pump is operating it sends current to the air valve which heats the bimetal strip and causes the valve to close.
Does ambient temperature also cause it to open and close? In other words do I need to test it by putting it in the freezer and oven as was suggested?
If I'm getting this right BOTH things (current and temperature) will make the valve close. |
|
|
| athorp |
Posted
Friday, Apr 30th 6:31am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 17
MN, USA
1979 323i, 1990 325i, 2002 540i |
Ok, here's an update:
I pulled the valve out and WD40'd it to try and make sure it wasn't stuck. At room temperature the hole was approximately 60% closed. After an hour in the freezer it was the same. I put it in the oven at 170 F and after 10 minutes it was 80% closed.
Once I get the car back together I'll test it in the car to see if the current opens and closes it further.
Based on what I've seen so far I'm wondering if the valve is sticking. This keeps it from opening all the way (and might explain cold start problems) and also keeps it from closing all the way (explaining high idle when warm). |
|
|
| Atle |
Posted
Friday, Apr 30th 7:41am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 19
Norway
Bmw 320/6 82 Bmw 323i 79, Bmw 323i 82 Bmw e30 320i cab 88 |
Yes ambient temperature also makes the valve open and close. For example when you have you car parked outside on a hot day the air slide will be partially closed.
When you have your car park outside on a really cold day the valve would be open. This is for giving the engine enough air for a cold start.
When the valve is closed there should only remain a very little hole trough the valve. If the valve isn't closing properly you will get an high idle on a hot engine.
Check the resistant trough the heating element. Use a ohm meter. The should be some resistenat. If its not the heating element is broken, and the valve will have problem closing.
You can also see the vavle closing if you jump lead you fuel pump relay socket as mentioned earlier.
|
|
|
| Atle |
Posted
Friday, Apr 30th 7:44am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 20
Norway
Bmw 320/6 82 Bmw 323i 79, Bmw 323i 82 Bmw e30 320i cab 88 |
If your vavle was 60 % closed after a trip in your freezer a assume you will have a very low idle when your car is cold. Do you have to sit on the accelerator pedal with your foot to keep it running? |
|
|
| athorp |
Posted
Friday, Apr 30th 10:26pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 18
MN, USA
1979 323i, 1990 325i, 2002 540i |
When it is below freezing it does take a lot of gas to keep it running at first.
When it is really cold (often here in Minnesota) it won't start at all. |
|
|
| Atle |
Posted
Friday, Apr 30th 10:52pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 22
Norway
Bmw 320/6 82 Bmw 323i 79, Bmw 323i 82 Bmw e30 320i cab 88 |
I would go for a new/used air valve, since your valve have problems opening in cold weather.
Broken auxillary air valves is a commen problem om k-jet injection. Besides our cars are now over 20 years old, and just about everything could stop working at this stage
|
|
|
| Knight |
Posted
Wednesday, May 5th 4:44pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 45
Sydney, Australia
1982 323i Baur |
Hi All,
Thanks for the tips on checking the Aux air valve! Wasn't sure about mine (coolant heated model), so checked it and it works a treat! Gave it a clean (amazing stuff that WD-40) and popped it back in!
Now I just have to paint and replace the exhaust manifolds and heat shields!
R |
|
|
| g323 |
Posted
Thursday, Jan 3rd 2:53am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 220
California
323i 1982 |
Mine definatly moves back and forth, but im not sure if it closes all the way, does it need to? im about to reinstall it
any comments would be helpful |
|
|
