Firstfives.org

CBradio · Joined: 06 Apr 2012 Posts: 52 Location: Brooklyn

Listed as #15 as "expendable" on the lamdba conversion FAQ EGR removal portion is a "speed switch". This is the aluminum box under the coolant tank mounted on the drivers side wheel well.

most of the wires go to the unnecesary three vac control items.

There is also a green wire, and a black wire that don't go to those items.

My question is: if I'm not upgrading to Lambda, is this a necessary item or can I simply unplug it and forget about it?

Might this be a sort of "ignition control module" for the earlier e12s?
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USA 49 state 1977 530ia

Mike W. · Joined: 30 Aug 2006 Posts: 1348 Location: Sonoma County

CBradio · Joined: 06 Apr 2012 Posts: 52 Location: Brooklyn

thanks for the info.
What does IIRC stand for?

As it happens I have a vacuum control valve on my distributor with a tube running to the throttle body.

So, do I need this thing?

This then leads me to ask: did I maybe need one of vac items on my car that went to this relay?

Mike W. · Joined: 30 Aug 2006 Posts: 1348 Location: Sonoma County

CBradio · Joined: 06 Apr 2012 Posts: 52 Location: Brooklyn

Ah I understand.
I was the one confused- there is no electric vacuum switching valve, it is only the vacuum pictured as #6 mounted on the distributor.

All the vacuum switching valves {3 of them on my car red, white, blue} have been removed, as well as the air pump, and the rest of the EGR stuff, save the reactors now; they are capped off.

as far as the speed switch,
I read one post where a pin pierced the insulator and got grounded to the body, causing a no-start

I don't recall the german name but the speed switch relay as my haynes calls it translated to digitizer or digitalizer from german.

CBradio · Joined: 06 Apr 2012 Posts: 52 Location: Brooklyn

Here it is:
"Drehzahlschalter" - bosch # "0 335 530 014".

the "digitaler"
I've seen it also as "speed switch relay"
and "overspeed switch"

It doesn't seem necessary but was shorting out my system I think....
hopefully did not do damage to my ECU or something.

Mike W. · Joined: 30 Aug 2006 Posts: 1348 Location: Sonoma County

I haven't messed with those in a looooooong time, but I think they shut off EGR over 3K RPM, so they would have to get an input from the distributor to know that. And if they got a distributor input and were shorted, could short out the distributor causing a no run situation.

BMW played some strange games with smog to get good HP in those days of 120HP V8s, but they weren't great systems given that 528i's were quicker with less rated HP.
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Mike W.

1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter