81sc, would like a non-working TTS

[ahh911]

Hi,

Asking a favour, I'd like one or two non-working thermo time switches that could be put in an envelope and mailed. (81 sc)

I'm planning on opening it up, removing the internals and replacing with an electronic circuit that will vary the cold start valve duty cycle with temperature, but want the connector to look original so that will be re-used. That way I can control the start-up vs post fire-up mixture.

Please PM if you have some old broken ones lying around. I guess we can ship any old way.

Tony if you're out there, any in your trash bin?

Thanks,
Phil

[fanaudical]

Sounds like a neat project. Do you mind sharing your sensor rebuild when you do it?

[ahh911]

fanaudical,

Sure, it will be nothing more than a 555 timer with a NTC temperature resistor, an nmos power resistor and some caps. Hopefully can find a variety of NTC resistors than can be swapped in to meet the startup characteristics. So nothing fancy, just basic elements to keep things as simple as possible. Once you go digital, it's a real pain.

The circuit will work I have no doubt, but I don't know the minimum on/off time that the csv can run at, so that might be a limiting factor. Probably a 250ms nominal period, who knows. I like the idea because the initial temp based duty cycle can be ramped up from low to high as it cranks over, (or high to low) or a fixed duty cycle based on the NTC resistance. We'll see if any of this is useful once on the car. Even simpler is a one or two second hold off for the CSV, so if no fireup within that period it feeds the extra fuel, can make this delay temp dependent as well. With an in spec wur I want my car to start within 3 seconds even after sitting for 3-4 hours, that's when I need extra crank time, otherwise it's a beautiful smooth start under all other conditions.

Phil