i got my scangauge setup to read MPG, engine load, GPH, and avrage MPG. when i'm coasting and take my foot off the gas it says 9999MPG and 0.00GPH. it's done this since i've updated it to have XGAUGE too. my interpratation of this is that the computer has sut off the injectors causing leanburn.
my question is does that sound right and do 7th gen civics have leanburn like the VX's do?
also if i set it up to hybrid can i shut the ign off to kill the motor going down a hill and still get MPG numbers?
it's a 2002 civic EX D17A2 w/ VTEC-E, CA emmisions.
Shutting off the injectors isn't running lean. It's running no fuel at all. No mixture is being burned. What you're seeing is DFCO, for Decel Fuel Cut Off. Honda implemented this as early as 1988, as soon as they started putting computers in cars.
When you let off the throttle above 1000 RPM, the injectors stay shut. The road pushing on your wheels, through the axles, through the transmission and clutch, pushes the crank and keeps the engine running. This has a very small benefit to mpg unless you can really exploit it on long downhill coasts. Mostly it's done to increase engine braking, decrease emissions and extend engine life. Squirting fuel into the combustion chamber when it's not needed causes it to run rich and this washes the oil off the combustion chamber walls increasing friction with the piston rings and poor sealing for blowby gasses to escape by.
Being that your engine is VTEC-E, I'm sure it has a version of lean burn probably comparable to the CA version VX. There are emissions restrictions and the lack of a wideband limiting how lean the calibration can go.
Hmm...I think this answers my unanswered question about the scangauge's GPH reading. I posted asking if it actually measures GPH or if it merely calculates it based on other variables. Granted, it doesn't answer the question conclusively, since the SG could just be detecting DFCO...