Quote:
Originally Posted by Bataleon
... When I start my engine it idles at 1200 rpm until the coolant reaches 140°F (60°C) after which the revs drop to 850 rpm. At the same time the fuel flow rate drops from 40cc/min to 20cc/min.
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So at the high idle you are running about 0.63 gallons/hour, which seems about right.
With the help of a custom tuner I was able to get the idle on my Focus (notorious high idlers) down to 600-700 RPM within a very short block from my house, instead of 1200-1400 for the first 20 minutes or so and a then drop about 900-1000, which was the lowest.
So now coasting in neutral from the end of the first block I am consuming 0.33 gal/hr, and within a minute later I'm down to 0.25. Fully warmed up I'm idling at 0.21-0.23 instead of formerly about 0.35. Also, the engine now drops to low idle in about half the time it previously did (3 sec vs. 5 to 7), which makes the car more predictable and drivable.
On my UltraGauge I'm seeing much better MPG on short trips even from a cold start; probably a 25% improvement on those -- 20 vs. 15 or 16 on one route; 26 vs. at best 19 on another which is mostly coasting. Just my sense of it; no practical way to do A-B-A testing on this. I'm still in early trials on this.