Okay I'm finally going to not be lazy now and share some data I formatted into charts. I'll say in advance, I wasted quite a bit of fuel by ecomodder standards, so don't cringe so hard lol.
The first 10 minutes of driving today:
Well immediately, I see why P&G didn't do s***. The accelerator pedal position is not scaled correctly but you can see that one peak where I floored it. Even though I was only pressing the pedal about halfway, manifold pressure is atmospheric and load is 90%, engine is running in the 13.x AFR :/ No wonder people gain so much mpg from just about any performance tune. That said, this means I was burning ~10-15% more fuel than I should have been on the freeway, so with just a throttle remap, 39 mpg => 44 mpg should be
easily within reach, and with high load fueling table cells adjusted 45 should be a piece of cake. Who knew this car was so fuel efficient!
As for around town driving, it's basically impossible to not be running rich all the time while accelerating, so that should get a noticable improvement too. Right now I'm getting maybe mid-high 20s mpg "city" driving. Cutting fuel burn by 10% in all cases would kick me up to 30 which is very respectable for a 2800lb car.
I had driven about 1 mile and walked into the hardware store prior to this log, so the coolant temp starts at 65ish. It appears that coolant takes around 5-8 minutes to reach operating temp, seems typical. Cat hits ~225C in 1 minute, which sounds kind of slow? Well, it passes CARB testing so I guess it's okay lol.
Idle fuel flow is 0.26gph at 980rpm fast idle, settles down to a surprisingly low 0.17x ish gph! That's lower than my MR2's 1ZZ-FE at 0.18x! On that note, the engine actually pulls pretty strong at low rpm so I am optimistic about a low idle speed working. The idle does sometimes hunt a little but after 3 years of 1ZZ quirks it doesn't bother me.
Since my P&G was a total fail, let's take a look at some steady state 6th gear cruising data:
It was hard to keep my foot steady but you can see that at just 42% load it's already going rich. As you can see from accelerator position vs. engine load, this throttle is CRAZY sensitive.
Catalyst temperature was right around 600C, if you use that line as a reference you can see around 35% load will hold 65mph, and MAP is at ~6.5 psi ~ 44kpa ~13mmHg. My 1ZZ-FE ran around 9mmHg by comparison, though it was revving 25% faster. That said, it was fighting a bit more aero drag too, so the FA20 represents a significant improvement.
Awesome. Note that catalyst temperature is well below the 700C continuous operation rating, so we have quite a bit of room to play with going lean.
So tuning:
1. Remap throttle, smooth out the requested torque ramp-up. I'll check out the tables other people are using but I feel like to get good mpgs I'll have to smoothen the response a bit more.
2. Borrow an off the shelf ignition and fueling map, then lean out a few more medium load cells. Gotta keep that engine running stoichiometric while pulsing.
3. Set 1600-3600rpm, 2nd lowest load cell up to the 43% load cell to leaner than stoich, maybe like 1.14 lambda. That comes out to the same amount of fuel injected as 36% load at stoichiometric. I'm thinking a few cells can probably go to 1.2, but that'll take experimentation.
4. Check intake cam settings, keep it at max retard for a little longer for low pumping loss if applicable, dial exhaust overlap back a little to stabilize lean burn.