Bosch MFI "speed switch" / zeitschalter

[npvpositive]

Was wondering whether most people here run their cars with a functioning Bosch zeitschalter (aka: relay dashpot, speed switch, RPM transducer, 901.615.111.00) or just have it disconnected?

The dashpot is that little silver box that provides fuel cutoff on overrun and improves mileage. I know that a lot of the race car types just disconnect them.



Mine is acting up so I'm running it disconnected for now . . . replacement is hard to find and expensive.

[npvpositive]

Anyone? No one? So silent . . . so very silent . . .

[epilot]

nick

i dont run it on the 2.4

craig

[HughH]

as far as I know mine is working, or at least it was when we were fine tuning the MFI earlier this year

[mrar]

My dashpot is connected but the adjuster screw on the cutoff switch is backed right off so doesn't contact the switch at all.

[Terminator]

backfiring often occurs if its disconnected

[epilot]

backfiring often occurs if its disconnected

clyde
there is a difference between backfiring and flame throwing ...

[mrar]

Mines not backfiring....flame on!!!

[Terminator]

Must be running lean the "experts", of which I am not, always look to this switch as one of the first issues with MFI

[mrar]

Maybe. I was told by someone in the know"not to funk with it if its running well" and if it was to run better than it is now it would be a nice surprise!

[Terminator]

Sounds like great advice to me

[72TE_KIWI]

An old thread .. but just to add that the Speed Switch function can be handled by programmable ignition such as Parts Klassic, Daytona Sensors CD-1 or MSD doing away with the aged electronic boxes ... set rpm limits in software and trigger the MFI fuel cutoff solenoid via a mini relay. Mini relay can even be hidden in the speed switch case to preserve looks.

[Stuttgart]

Mine was flame throwing and backfiring when it wasn’t working.

[mario lanza]

I believe Porsche Centre Melbourne had mine rebuilt by Varasso electrics.