This switch kills my engine? Could this be the cause of my issue?

[Sporttracguy]

1970 911E with MFI

Today I took the car to work (about 20 miles mixed freeway and stop/go) and the car drove great until I came to a stop on the freeway off ramp and the car died. Turned the key and she started right up again and then died...one more time, turn the key and she starts right away but I had to pull the floor throttle to keep the revs above 1400 or so.

My assumption is either a vacuum leak or fuel issue....

But then I also noticed this adjustment bolt that looks like it is supposed to be depressing the switch (don't know what this switch is for) but it is adjusted to be hovering just above the switch instead? When I have the car idling and press this switch the car dies? Could this switch be part of my problem?

[IMG][/IMG]

[john walker's workshop]

It activates the relay that pulls the MFI rack back to the idle position and then lets it go under about 1300 RPM. Obviously the relay may be tits.

[Bob Kontak]

Originally Posted by john walker's workshop

It activates the relay that pulls the MFI rack back to the idle position and then lets it go under about 1300 RPM. Obviously the relay may be tits.

God bless John Walker.

I am guessing the expression may be "Tits up in the ditch"

[john walker's workshop]

Pull off one of the wires to temporarily disable it. Not the proper fix but it should keep idling.

[Sporttracguy]

Ok, pulled the wire, started her up and let her run. Granted it's not warm anymore but idle settled around 1100 and seemed to run good. Revved the engine a few times and it settled again around 1100... Plugged the wire back in, revved it and it died instantly.

So the question is,,,, what next? I'll try to drive her tomorrow and see if I can keep her running. (And find out if this is actually my problem)

Thanks

[JJ 911SC]

Originally Posted by john walker's workshop

It activates the relay that pulls the MFI rack back to the idle position and then lets it go under about 1300 RPM. Obviously the relay may be tits.

^^^

[harvardma]

The RPM transducer or speed switch is supposed to make that switch only working above 1,500 RPM. If that switch is getting power below 1,300 RPM then the RPM transducer is the problem.

[tobluforu]

Same thing just happened on my car, I even have a rebuilt transducer I bought 6 years ago that worked great, for well, 6 years, and just pooped out. Otto use to rebuild them, not sure who does it now. I swear my cars runs better off throttle with it disconnected. I ran it this way up until 6 years ago when I decided to fix it. Will I replace/have it rebuilt, only if its inexpensive, until then it stays un-plugged for now.

[Sporttracguy]

Originally Posted by tobluforu

Same thing just happened on my car, I even have a rebuilt transducer I bought 6 years ago that worked great, for well, 6 years, and just pooped out. Otto use to rebuild them, not sure who does it now. I swear my cars runs better off throttle with it disconnected. I ran it this way up until 6 years ago when I decided to fix it. Will I replace/have it rebuilt, only if its inexpensive, until then it stays un-plugged for now.

Ok, that makes me feel a lot better. If I get a chance, ill pop open that transducer and try to figure out what went wrong.

Thanks

[dafischer]

Here's a link to a good schematic and write-up, from 2002.

rpm transducer... see anything wrong?