MSefi.com read only forum (Jan.15,2018)

Hi, question for an amateur engineer here.

I'm putting together an EFI setup based on the MegaSquirt for a 1973 MGB with the standard 1800cc B Series engine. This has a temperature sender in the block. However, a friend has suggested using a modern temperature sensor instead for better control by the ECU.

If I do this, how can I provide an output to the original temperature gauge on the dashboard? It's a Smiths instrument, of the one-wire type. Grateful for any steers and explanations.

Thanks,

Adam

ariddett wrote:Hi, question for an amateur engineer here.

I'm putting together an EFI setup based on the MegaSquirt for a 1973 MGB with the standard 1800cc B Series engine. This has a temperature sender in the block. However, a friend has suggested using a modern temperature sensor instead for better control by the ECU.

If I do this, how can I provide an output to the original temperature gauge on the dashboard? It's a Smiths instrument, of the one-wire type. Grateful for any steers and explanations.

Thanks,

Adam

I agree with your friend! The one wire sensor will likely not provide what you need for MS. If possible I would install a second sensor and retain the OEM for your gauge.

Do you have a place on your MG engine that might accommodate it?

Ken

Yes - keep the dash gauge electrics as is, and fit another two wire type for MS. A block return type could cause all sorts of problems for MS. IIRC, there are thermostat housings that can take a sensor (some BMC A series engines?) - re-site the dash one there and fit the MS one to the original place. It's more important MS knows the exact coolant temp than your gauge.

It would be theoretically possible to share the new sensor with your gauge - or possibly use a spare output from MS to drive it. But this would require one off specialist electronics.

Thanks trakkies, well that nails it then. I'd hoped it might be a simple option but never mind. There is a precedent for fitting another sensor above the original by drilling into the thermostat housing and tapping it, so I will look into that.

Cheers again!