Ive put like 6000 miles on this thing in two months, have gotten a best of 40.1mpg out of it, and just the other day found out I've been running on 3 cylinders the whole time. The wires for one of the injector plugs were loose. Now I'm pretty sure this is why I was getting abysmal mpg with the o2 sensor plugged in, like 32 mpg. I would get 38-39 without the o2. I would imagine missing a whole cylinder worth of fuel would look quite lean to the o2 sensor and tell it to dump in as much fuel as possible.
I thought the car was quick already but holy crap this thing screams now. It will rip the tires off in 1st and half of 2nd and has no trouble maxing out the 85mph speedo. I only have a few issues now, one of which is the rear suspension is worn and is squatting under hard acceleration allowing the front end to come up and spin the tires. Another thing is Im running open exhaust now (hearing that turbo whistle coming from a FESTIVA is awesome) and theres too much flow basically, the wastegate cant bypass enough, so it creeps up to the 11psi overboost cutout, which you can see in my video. I need a chip for the ecu that allows you to go over 11psi.
Heres a video of me ricing around, don't mind the granny shifting, overboost cut, or oil light.
ON THE FLIP SIDE OF THINGS (the more mpg friendly side)
Its REALLY friendly to drive ecomodder style. This thing lugs down to idle. I can seriously drive around in 5th at 25mph, about 1000 rpm, and then get up to 55 just fine without downshifting. Theres gobs of low end torque for low rpm acceleration and cruising, and Im finding that its pointless to row thru all 5 gears when I just end up shifting every 5mph (which is every half a second or so lol). I could probably skip 1st, and just go 2-4-5. I swapped the .8 5th gear thats stock in the capri trans to a .71 from a 626. It runs about 2200-2300 rpm at 55. It could probably cruise 55 at 1500. I think I have the tallest 5th gear that came in any G25MR transmission though. The engine just seems to work so much less in the 1800lb festiva than the 2500lb capri. I only wish I could still run the little 12 inch festiva wheels instead of the heavy 15 inch capri wheels.
Now that I have all 4 cylinders working Ive plugged the o2 sensor back in. Im hoping to maintain 40mpg (If I can keep the right foot relaxed), and I'd be super happy if I can get 45 out of it. I averaged 34.5 in the Capri with a best of 38.5. I averaged 47-48 in the stock festiva with a best of 53. So I think logically this should get somewhere between that. I'll keep y'all posted on it.