Can anyone explain how the thermostat in a MFI works?
06-27-2003, 05:12 PM
#1
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Can anyone explain how the thermostat in a MFI works?
I'm interested in understanding the mechanics of the thermostat of the Bosch MFI on my car. What happens when hot exhaust gases blow through it etc?
Thanks
Lefty
Thanks
Lefty
06-27-2003, 08:45 PM
#2
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Hot exhaust gases actually do not blow through the thermostat, the air that is heated for the cabin actually paases through the thermostat. The hot air blows over some discs attached to a control rod, as the discs heat up they expand therefore pushing the control rod further in the pump, the further the rod goes in the pump the leaner the mixture.
06-30-2003, 05:34 PM
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rvdv,
Could you go further and explain the basic function of the system. Is it just RPM, temp and throttle position that determines fuel qty?
How does the 'space cam' relate to engine type? Is it just a lobe dimension that is higher for a larger engine?
I am programming an EFI system for an engine that had MFI and was curious about the inputs to the MFI.
The EFI has RPM, temp and manifold vac as I am now using it.
Art
Could you go further and explain the basic function of the system. Is it just RPM, temp and throttle position that determines fuel qty?
How does the 'space cam' relate to engine type? Is it just a lobe dimension that is higher for a larger engine?
I am programming an EFI system for an engine that had MFI and was curious about the inputs to the MFI.
The EFI has RPM, temp and manifold vac as I am now using it.
Art
06-30-2003, 07:48 PM
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Art,
You are correct about RPM, temp, and throttle position governing fuel quantity. There is one other sensor on the top of the pump which senses barometric pressure, this sensors also governs fuel quantity.
The pumps also have a space came that is matched to the engine. There was a unique cam for the "T",
"E", "S", and "RS" engine, this space cam is profiled in such a way that the fuel delivery matches the profile of the camshafts. The beauty of the MFI system is that thhe fuel is injected at a very high pressure, about 225 PSI, therefore creating a very fine mist of fuel which makes internal combustion much more efficient.
rvdv
You are correct about RPM, temp, and throttle position governing fuel quantity. There is one other sensor on the top of the pump which senses barometric pressure, this sensors also governs fuel quantity.
The pumps also have a space came that is matched to the engine. There was a unique cam for the "T",
"E", "S", and "RS" engine, this space cam is profiled in such a way that the fuel delivery matches the profile of the camshafts. The beauty of the MFI system is that thhe fuel is injected at a very high pressure, about 225 PSI, therefore creating a very fine mist of fuel which makes internal combustion much more efficient.
rvdv
