Tossing this out for discussion.

My V12 has (as many do) both the electric and vacuum full load enrichment switches.

I know that some non-USA market cars had only one of the two....although I can't remember which one it was. I was wondering if this redundancy is really needed given that I have a Euro spec ECU, no cat converters, no oxygen sensors...and the 3.31 differential.

I don't object to having both but removing non-essentials from the engine bay doesn't bother me either.

Thoughts?

I'm inclined to keep just the electric switch.

Cheers
DD

 

The electric is possibly more important than the Vac switch for some.

The vac switch will richen as you accelerate, not by "standing on it" so to speak, when that acceleration has NOT rotated the capstan enough to activate the mechanical switch.

BUT

At higher speeds/revs, the vac switch MAY still "see" enough Vac to keep the contacts open, hence Closed loop. That is where the mechanical kicks in and does the switch over to Open loop.

Mine had both, and I rarely had the mechanical kick in, leg issues prevented getting much more than 1/2 throttle at best. Hence the "adjustment" to the Blue/White switch I have written about.

Talking with Greg in France, his is UK car, and has the Vac only, NO mechanical.

 

The vac switch is, in my view, the one to keep. UK spec cars had this switch only, no back-up microswitch. The two do the same job, they are wired so that whichever closes first switches to full enrichment on the same ECU circuit. The vac switch is passing current, thus enriching the mixture, at a vacuum LESS THAN 3.5 bar, and it is easy to test it with a MityVac and a test light and a 12v source. These are very reliable switches. I got worried about mine a few months ago and managed to find a NoS one. I tested the new one and it closed at exactly the correct reading. Then I tested the old one, and that did too, in spite of 35 years in the engine bay and 150,000 miles.
So i do not think the microswitch is needed, and it is certainly a less robust switch than the vac one.

 

I don't know much about this but I do know that for ever owning my car, until recently, the electrical switch was disconnected (I hope I am understanding and speaking to this rightly). I never gave/give enough throttle (except maybe twice) in about 1 or so years to engage the mech switch on the capstan - so I guess I don't think it soooo important or needed.

On the other hand, since getting the know how from folks here - modestly understanding how it works - I've connected the electrical switch and noticed a day and night difference in regular driving,,, off the line so to speak,,, with all the starts and stops of city driving. The electrical switch seems to make that initial start out from idle smoother and more efficient in the way the engine responds to peddle/throttle position...

 

I can't explain the result you've achieved but It's hard to argue with success!

In theory the ECU would never know if your electric enrichment switch was connected (or not) until/unless you reach about 2/3 throttle. Before then it's just....well......sitting there doing nothing.

Cheers
DD

 

Hmm. The way I understood it (and that could have been mis-understood it) was that at that moment from going from straight idle to hitting the peddle on take off at a light say, the change in vac in that switch signaled the ECU to zap a bit more fuel into the injectors/cylinders to enrich the mix so I didn't get that hiccup like hesitation when taking off. I'd always had that hesitation and messed around with throttle linkage and the arms 20 times trying to git ride of it. Never worked 100% as a solution.

After I hooked up the switch, problem/hiccup/hesitation disappeared. To this day I don't know what would happen at or after 2/3rds throttle. I dont get enough opportunity in the city to get on the peddle like that and, sad to say, I still don't know this car well enough - or drive it enough on open roads - to know that 2/3rds throttle area as well. Some day - maybe this spring