early 323i air slide valve

Post Fri Jul 10, 2015 3:12 am

My 1984 323i has good cold idle(1100rpm), but is dropping to 500rpm when warm. The wiki says the Air Slide Valve might be the culprit. Is there any way to adjust the cold idle, or do I just replace the old valve? Also if mine is the older injection system that uses water temperature to alter the warm idle, is it possible to move to a later type of air slide valve?

Post Fri Jul 10, 2015 10:23 pm

There is a nut (6mm?) on the air slide valve. Slacken it off. It's in a slot. Move it towards the outer edge of the valve and retighten the nut. That raises the idle.

Post Sat Jul 11, 2015 11:15 am

DON'T touch the air slide ! That sounds like it is working fine. There is an idle screw on the engine. Adjust that when the engine is up to temp , BUT , the obvious question is, why has your idle speed dropped ? Have you checked your ignition timing ? Is it correct ? They usually are NOT !

Post Sun Jul 12, 2015 12:20 pm

OK here is what happened. My son dropped into day. He said the slide valve was dodgy. So from his pile of spares he found and installed a slide valve that has a built in thermostat. He took the two small hoses that carry water into the old Slide valve off and replaced them with one hose that just loops the radiator water back. This newer valve is warmed by the motor and when the motor gets to running temp it has a thermostat that opens the valve up. It works great. With the engine up to running speed he turned the idles screw while I watched the Tacho. We set the warm idle at 750rpm. It all seems sweet now. Cold idle is about 1100rpm. I forgot to ask him what car the new slide valve came from. I can find out if anyone is interested.

Post Tue Jul 14, 2015 3:43 pm

The replacement slide Valve came off of a Nissan Silvia 180 sx. It has worked well.