MPG check today…
First crank start. Idle begins at 1200 rpm. Can’t call idle perfectly stable—hunted for 1 cycle down to 1000 and up to 1300 then stabilized at 1200. Runs at 1200 for some seconds, then slowly settles to 800. Filled tank at Shell till pump itself cuts off. 93 oct. Background notes: Tire pressures cold: 25 F / 29 R (Found tires wear better—more evenly across width—with lower than recommended psi. I realize there is the question of which is more economical, higher tire pressure for less fuel use, or lower pressure for longer lasting tires?) Oil now and after engine’s break in: Motul 20 - 50 synthetic. (Break in was with Motul mineral.) Gearbox: 5 spd. Engine mods just done: 964 cams set to 1.45, SSI exhaust, Dansk 2 in 1 out muffler. Sound is slightly more robust than stock but no drone and not loud.
Went downtown Miami to Islamorada and back. Returned to exactly the same Shell fuel pump that I filled with. Did same refill allowing pump to cut itself off so fuel used should be spot on.
Miles driven.
Refill gallons.
Miles put on are highway for the most part with sections of stop & go in Miami and in the Keys. Only a few heavy footed accelerations were made during this test. Highway cruise = 60-80 mph. MPG = 27. Good news (so far.) No idea what the AFR is. Am inclined to think that without an Ox sensor, there’s nothing telling the ECU what the burn status is. Am guessing the ECU must default to some set measure of fuel delivery—total guess so do not quote me. Manual check of AFR obviously needs to be made. Thinking this through, it seems sensible even with an Ox sensor installed to check the AFR.
Mission today was to drive the fuel tank down immediately to see if there is or isn't an improvement from where this fix started, that being 11 mpg (city.) Clearly things are headed in the right direction. Now, and with last fill up just made, city mpg test starts. Will take several days before next refill. Update when city number is had.
Just received the new Ox sensor. Setting it aside for the time being---not installing it.
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