acceleration hesitation power loss

[nepal1344]

Ok I will start from the top just in case something I think is trivial may in fact not be. Car is a 2008 2.0L 5spd GS model sedan.

Car has been running great for months (just replaced plugs 3 or 4 months ago). I started getting a click in the suspension that I identified as a sway bar link. This is fixed. Right before i changed that i started getting light hesitations or random power loss while driving on the highway. This puzzled me but i assumed i had water in the fuel or something of that sort (I had recently run a tank of premium and this started right before the tank hit 1/4 full) so i dumped an appropriate addative in to dry the fuel and added some more. This did not help at all. Through all of this there is no cel. We investigated further though maybe the maf so i have a buddy with a 3 and swapped in his known good maf and no dice. He also has spare engine parts so we swapped the injectors bc we thought fuel supply issue. This did nothing as well. We then changed coils out of confusion and checked my plugs. Plugs still look good and while plugs were out ran a compression test all was goo there too. None of this has fixed my issue but i have managed to narrow when i can force it to do this and when i can force it not to. If i keep the rpm under 3000 it's fine no issues. The issues happen between 3-5000 and it feels like you hit fuel cut. It will cut for a sec or so then kick the power back in and sometimes it does it repeatedly between those rmps. If i keep it over 5 it's fine under 3 its fine but between it goes crazy. This only happens under load of accelerating as well.

Any help or advice on this issue would be appriciated. If you have any questions that may help identify the problem please ask and i will do my best to answer them fully.

Thanks in advance for the help.

[Nikhil Pali]

Which intake you running. This happened to me also. I got Injen CAI with dryflow filter. Apparently, after cleaning, I oiled it by mistake which I wasn't suppose to. It caused the same acceleration hesitation every time I accelerate. Try some other filter if you haven't, maybe that would fix it.

[Genpu_Mz3]

it may be a tranny problem.....

[Kiyomi]

sounds like the ecu might be the next place to check or replace (try someone elses before buying). going from closed to open loop which is around 3500-4000rpm, and/or having to do with the intake butterfly valves not opening fully, or not at all.

or, just take of your cai, and put back your oem box/filter. see if that changes anything.

[nepal1344]

Already gone back to factory intake just to be sure so eveything I'm running is factory equipment. On a side not my fuel ecoomy has gone to hell a couple weeks prior to this problem which is why I thought fuel issue. It sounds like the intake is open but it cuts the fuel randomly. It almost feels like when the vvt should kick in it cuts out until 5000

[nepal1344]

So the code i seem to have picked up is P2251 it says an O2 sensor circuit open bank one sensor one....could that cause all my problems?

[nepal1344]

Ok so I found out that code is commonly caused by the bracket wearing trough the o2 sensor harness. I checked and indeed had one wire that was wore trough grounding out to the bracket. I have repaired this and all my problems are gone. Thanks everyone for your thoughts on this.