Hi everyone! Since my family's starting to trust me more with the car, I get to drive it on longer trips now which means I now get to drive the car on highways (Yay me!).

I've been complaining about the car's unusual thirst for petrol for the past months and so far, we've only cleaned the first O2 sensor. Fuel economy improved very slightly after that (around 8 Km/L from 7.5 Km/L) Since someone else pays for my gas, it's not that important right now. What's been bugging me is the lack of power the car's been giving me on the highway.

A week ago, I wanted to overtake another car (Toyota Vios, 1.3L engine). We were both doing roughly 100 Km/h on the highway. I gave the car full throttle, expecting to easily overtake the other vehicle, but the car refused to go faster. The other driver actually pulled away from me when I changed lanes to overtake. After I decided to ease off on the throttle (around half, I would say), the car suddenly decided to pick up speed and I caught up with the other vehicle.

Now. Has anyone had this experience before? I'm suspecting dirty fuel injectors, but my dad keeps telling me to just leave it be. Not sure if it's related, but the car sort of chokes and shudders very slightly when you give it full throttle from idle. It would choke for a brief moment before revving to the redline when I do that.

I've checked the usual easy to check things. Oil, Air filter, AT Fluid and data from the OBD scanner. Only thing out of place in the readings is the occasional misfire and a high LTFT (15%). That reading strikes me as odd, since my STFT reads nicely. Any ideas on what I should be looking at?

Is it an automatic or manual? If it is a manual, did you change to a lower gear then put your foot down? if automatic, did you put your foot down hard enough to 'kickdown' on the gears? I ask this not to insult you, it just sounds through your description that putting your foot down in top gear resulted in not much acceleration, it wouldn't without first dropping to a lower gear.

It's a 4-speed automatic. You're correct, it didn't downshift to 3rd when I did that - but still. You'd expect to see /some/ acceleration from with that kind of throttle input. When I put my foot down, it stubbornly stayed around the 100 Km/h mark on my speedo. When I eased my foot off, it still stayed in 4th but it began to pick up speed, reaching around 145 Km/h until I had to slow down for the toll station.

Hmmm... Is there an issue with kickdown? does it normally kickdown when it gets floored?

Now that you mention it, it's hard to predict when it'll kickdown. In low speeds, a sudden jab at the throttle will immediately make the car downshift but not on the highway. In high-ish speeds, I find that I either have to pump the throttle a few times or use the sequential shifter to get it down to 3rd gear. Not sure if the car is supposed to behave like that though, since I've only had the car for half a year.