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

Hello all, we're looking at using the MegaSquirt on a university project, but it's a little different than it's usual application. We have a custom-built supermileage vehicle that we compete with that gets over 2,700 MPG. It uses a 50cc single cylinder carburated Honda engine, which we're converting to fuel injection. I've been doing some reading up on the MegaSquirt, and it sounds like the coolant sensor is necessary for the ECU to operate. For our project, we don't have a cooling system, because we try to keep the engine as warm as possible so it doesn't need to warm up after we coast and burn.

So I guess what I'm asking is, can we operate the MegaSquirt by just tying the coolant sensor line high or low, rather than actually hooking up a coolant sensor?

You'll have to forgive me if I'm asking silly questions. I'm the team's computer engineer, not a mechanical engineer, so while the electronics don't scare me at all I'm not very knowledgeable regarding engines and whatnot.

Thanks for your help!

The engine coolant temp is used for determining warm up enrichment and for such things as turning the engine radiator fan on and spark retard. In your case I'd substitute a fixed resistor to keep the input to MS from drifting, however I think there is a "fail safe" value built in.

You could substitute a cylinder head temp sensor for data logging purposes.

HTH

Try searching the forum for something like "air cooled VW engine temp sensor". Whatever they do should work for you.

Or you could do as mentioned above, fit a fixed resistor in place of the sensor and set MS up to ignore coolant temp. (no cold-start or warm-up, no fuel adjustments on over-temp, no temp-based timing adjustment, etc)

Sounds like a neat project.