I hate to let a good off-topic post go to waste... :-)
A typical computerized engine management system will have no fuel
pressure sensor, fuel temperature sensor, or a sensor for fuel flow. The
computer assumes a nominal fuel pressure set by the fuel pressure
regulator and it also knows an approximate temperature from the other
temperature sensors on the engine.
Hard to believe huh?
The engine management computer will determine the the nominally correct
injector pulse widths from the combination of input data from the
assorted engine sensors such as RPM, air temp, air flow, water temp,
etc., and a predetermined injector pulse value stored in a "fuel map"
within the computer.
Obviously, this will seldom be 100 orrect. It doesn't need to be. The
engine exhaust gas is monitored via an oxygen(O2) sensor and final
adjustments are made until the exhaust gas has the correct amount of
oxygen in it. Once this occurs, the engine is said to be running "closed
loop." IOW, a feedback loop is setup and as long as the mixture is
within the lock range of the loop the computer will be able to
constantly adjust the injector pulse widths to keep the mixture optimum.
Oversimplified, but you get the point...
--
Jim
The ECM will take the
siddiq wrote:
2/9/2003 1:45:19 PM, Joe Gwinn <joegwinn@xxxxxxxxx> wrote:
i'd think by measuring injector pulse length, as mentioned before. somehow i doubt an inline-flow measuring device can be accurate
enough, easier to measure to how long injectors are open since they put out a set volume multiply by length pulsed.
Sounds plausible, although one would also need to compensate for variations in fuel viscosity with temperature, a matter of table
look-up.
i'm thinking fuel temp would be fairly stable once it reaches the engime compartment. for starters it get pressurized before it gets
sent, so that should stabilize cold tank temps, then in the engine itself, shortly before it hits the injectors, the metal tubing has
plenty of time to absorb ambient heat.
/S
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