EGR REMOVAL AND "THE SPEED SWITCH"

[CBradio]

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.]

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?

Yes. IIRC it just runs the EGR, although it may affect the vacuum retard too. If there is no vacuum switching valve between the throttle body and the distributor, it's only for EGR.

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

No.

[CBradio]

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.]

thanks for the info.
What does IIRC stand for?

If I recall correctly.

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?

I'm confused. Do you mean part #6 here, the vacuum box, with a rubber vacuum hose leading to the throttle body or a vacuum switching valve, ie a valve with an electrical connection in the middle of that hose? Or something different? If you are referring to the vacuum box, yes, you want to leave it in place hooked up, while it's a vacuum retard, it actually works much like vacuum advance, it retards at idle and doesn't retard at larger throttle openings effectively giving advance. Backwards, but it worked at the time for them.

[CBradio]

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]

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.]

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.