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Old 09-03-2010, 10:02 PM   #26 (permalink)
NachtRitter
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RippinRoo - '05 Subaru Legacy Wagon 2.5 GT
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Quote:
Originally Posted by brucepick View Post
Re. coasting downhill in gear to control speed - with injectors off.

IF your car burns oil in any significant amount, you might not want to do this a lot. The high cylinder vacuum will likely suck in a lot of oil - either through the rings or the valve seals, where it comes through to let it burn oil. You'll have a batch of oil in the cylinders when you fire it up with fuel. If so, you'd just be causing it to burn oil

You should be able to test for this. Try it, with medium-high engine rpms, on a longish hill. Restart it when needed, give it maybe 2/3 throttle, and watch for a blue-white oil cloud from the tailpipe. If you see it, it's from the slug of oil built up in the cylinders in that long coast with high vacuum.
Would it burn any more oil in DFCO than not? Seems that it'd be the same amount of oil getting sucked in whether fuel is coming in or not... the valves still open the same...
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