bmwe21.net forums

Continuing on from here (and thus to avoid hijacking E21noob's thread):
viewtopic.php?f=3&t=23283&p=248133&hili ... le#p248133

I've done a search on 'high idle' and 'autochoke' and such but I can't find any definitive answers to this problem.

When I first start the car (1982 316 1,766cc, standard Solex carb), it idles at about 800rpm. Obviously it's cold (both the car and the ambient temperature) so it's a little rough, but it starts OK and doesn't stall. But as it warms up, the idle grows higher and higher until, once at full operating temperature, it's idling at about 1,600rpm. In among the other threads on similar subjects, it was suggested that the throttle linkage might be sticking open. But when I turn it off and then back on again with the bonnet open, watching the carb, as soon as it starts the throttle automatically opens back up on it's own. So it can't be a physical 'stick' in the cable because if that was the case it wouldn't settle back down at all. As it is, the throttle spindle rests fine when the engine is off, but something (the autochoke?) opens it back up again, causing the high idle.

I've considered warming it up and just re-setting the idle as per the Haynes manual, but I'm worried that if I do that it will be refuse to idle when cold, or if it turns out the autochoke is stuck on, one day it'll unstick and then dump the idle through the floor and refuse to run. There is a whistling/hissing noise, which I read somewhere could be a leak in the vacuum system.

Any ideas? Autochoke stuck on?

Along with this viewtopic.php?f=3&t=23410 - I'm completely unable to enjoy my car. These seem like two such small issues but I'm at my wits end with both of them.

You mentioned that when the engine starts the throtle automaticly opens a bit? I pressume it opens because the vacuumvalve pushes the throtle open? Maybe that has a vacuumleak? During warming up with closed chokeflaps it has a higher vacuum but when the chokeflap opens the throthle open also because of a bad vacuumvalve.

The vacuumvalve with the spring:


Try to turn in the screw so that the throtle linkage is set against the idle screw.(cold engine). Then start the engine (the regulator cannot open the throtlevalve)

It does look like the vacuum valve that's opening the throttle, yes. I had a thought after I'd typed that before: if it is the choke sticking open, I should be able to see it just by taking the air cleaner off and looking at it.

As I can also hear the hissing, I think a good way forward is to look for a leak in the system and try to fix that first. I have no idea if vaccum hose is easy to come across. Thing is, I'm not completely un-mechanically minded, I'm just not good with electrics (ie the other, battery light issue) and this is all new to me. Until I have an understanding of what's in front of me and how it works, I'm kind of lost. There seems to be a lot of vacuum hose and I have no idea what it all does. I'm used to Hillman Imps (also fitted with Solex carbs that I also hate with a passion) that are a little simpler.

But I'll try the adjustment you suggested. When I've next got a few days off. Thanks for your help, watch this space...

No problem. I have a diagram where al the hoses of the Solex 2B4 (your carb) must go to.

Good luck.

Any luck, Rocket?

Haven't had time to look yet. Strangely, it now seems to have settled down a bit - at least once it gets warm. But it takes ages to get there. It's odd. I want to have a better look, but I'm struggling to find the minutes in the day at the moment!