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Old 02-11-2012, 05:43 PM   #116 (permalink)
SentraSE-R's Avatar
Join Date: Jun 2009
Location: Bay Area, California
Posts: 1,485

Mean Green Toaster Machine - '06 Scion xB
Team Toyota
90 day: 48.92 mpg (US)
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Surprise, surprise. The elephant is still in the room.

I took the xB on a 10.4 mile P&G EOC drive (with mostly 18-32 mph delta), reaching 57.7 mpg. I ran without grill blocks. The engine coolant temperature reached Toyota's warm up temperature of 137F after 4.5 miles. Ambient temperature started at ~40F. Normally, with the grill blocks, EOC P&G warms the engine up to 137F in ~4 miles. At 137F, the blue dashboard temperature warming light goes off. Coolant temperature had reached 172F at the end of the 10.4 mile drive, v. a normal 185F

During the 10.4 mile drive, the cat lit up (exceeded 550F with the engine running) only once, during a pulse while climbing a hill. Total duration the cat was lit was ~1 second during the entire ~25 minute drive.

Let me explain. I watched the cat temperatures during each pulse. When I stopped a pulse, the cat temperatures lagged behind, and typically rose another 75-150 degrees a second or two after the pulse ended. If I ended a pulse at 375F, the cat temps usually rose to 450-525F with the engine off. Only that one pulse exceeded 550F with the engine running, and it was the highest recorded cat temp during the drive at 605F. Cat temps topped 550F half a dozen times in the 10.4 miles, but all these other occurrences had the engine shut off when cat temps were under 500F, and the cat temps topped 550F with the engine already off. In other words, by the time the cat lit, the engine wasn't emitting combustion byproducts.

So, I got 57.7 mpg on a 10 mile drive emitting pollutants the whole time through an unlit cat. I drove the warmed up car on three 10 mile loops in the same area, with engine-on P&G (18-32 and 25-40 mph deltas), and 35 mph cruise control. Ambient temperature rose to ~50-55F, wind <10 mph, sunny and dry.

18-32 mph 3rd gear NICE-On P&G 46.3 mpg, coolant temperature 185F, cat always lit*.
25-40 mph 4th gear NICE-On P&G 47.7 mpg, coolant temperature 185F, cat always lit*.
35 mph 5th gear cruise control, 45.7 mpg, coolant temperature 185F, cat always lit. Cat temp dropped to 970F on a downhill, stayed in 1100-1200F range most of drive

* Cat sensor 1 was 900F by the time cat sensor 2 topped 550F at 0.8 miles. Observed during cruise control loop.

Boycotting Exxon since 1989, BP since 2010
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac? George Carlin
Mean Green Toaster Machine
49.5 mpg avg over 53,000 miles. 176% of '08 EPA
Best flat drive 94.5 mpg for 10.1 mi
Longest tank 1033 km (642 mi) on 10.56 gal = 60.8 mpg

Last edited by SentraSE-R; 02-11-2012 at 05:52 PM..
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