It seems to be only under light acceleration right as I'm about to hit 2k rpm, like just over 1900 ish. It happens whether I'm going uphill, downhill, flat ground. I recently put in fresh NGK coils and plugs and it seemed to fix it for a few weeks, but now it's happening again and not just in lower gears, seems any gear light acceleration right as I approach 2k rpm is starts to hesitate. I guess its kind of a misfire, I hooked up my scan tool (foxwell 510 elite preloaded with mini cooper/bmw) with logging and tried to reproduce it, but of course it didn't do it even after 10 miles, yet it happens almost every time I drive. Ive checked the ignition wires, connectors, made sure new plugs hadn't already fouled. My PCV "valve" seems fine. Im not getting any codes so I want to believe it's not a sensor. I always let the car warm up until the rpm drops under 1k rpm. The hesitating happens sometimes when I first start driving, sometimes after an hour of driving but only ever just as I'm hitting 2k rpm under light acceleration.

I am running original timing chain, but could that really be it if its only happening exactly in the same spot? I think if it was the chain or valves, there would be other issues, or at least this issue would happen in a broader range of engine speed, but its only with that small margin right before 2k rpm. I have to let off the throttle and then reapply to get it to stop or it just keeps lurching like its losing power and wants to stall. Alternator voltage is stable even when its hesitating. It has fresh oil and coolant, full, regular oil changes, 0w30 Mobil1 euro (it also happened with 5w30, no difference) it happens on 91 and 93 octane. I look under the car pretty often for oil leaks, haven't seen any, no issues apparent witht he exhaust system. No other issues, noises, again no codes, nothing else seems unusual so I feel like I'm going to lose my mind haha I do have a backup car in case I need to rebuild the engine but ive never done that before. I'm going to test the fuel pump soon, not hopeful that it's the cause

I really hope its not a transmission issue, it doesn't seem like one as it shifts clean and isn't noisy. I'm hoping its something simpler but im running out of simpler. It doesn't do it under heavier acceleration, but the issue has me paranoid to drive hard, so I've just been driving easy, anticipating the hesitation and letting off the throttle when I know its about to happen, its fairly predictable. Im going to take another run with the scan tool, hopefully it doesn't magically not happen again when I do, otherwise it seems like my solution will be to just always have the scan tool plugged in lmao or i guess i can just go harder on acceleration and cross my fingers but that seems reckless and stupid. Ive heard people say "you have to drive these cars with a heavy foot" but im not sure here, seems like a recipe for a blown motor haha

 

Are you able to check for pending codes?

 

What ignition wires?

My PCV valve "seems" fine? How did you determine this?

You don't need to logging, and you don't need to duplicate the problem; if there is a problem, any DTC will stored in memory; if it's a misfire (and many other faults) freeze frame data will be stored with the DTC. If you clear the code, you will also delete the freeze frame data, so be careful deleting DTCs.

I had a friend with a 2001 Toyota Avalon, V6; she had the exact same problem ... hesitation under light acceleration, but fine with you floored it, no DTCs in memory. It turned out to be her VANOS (VVT in the Toyota), solenoid, so I changed it and the car was fine; 6 months later the other VANOS solenoid failed. The Avalon had over 200K miles on it.

OBTW, the diagnostic tests on the VVT solenoids passed.

 

No pending codes. Turns out it was spark plugs, 3 of the NGKs i ordered online were somehow gapped way to big. Got a fresh set, checked the gap, tossed them in and for the last 50 miles no hesitations. When I said the PCV valve seemed fine, I meant it was free of visible damage, didn't seem warped and the flap and setting were not visible warped or otherwise misshapen. Sure, it could have still been faulty, but unlikely imo. I have a fresh set of vanos solenoids for down the road, and im going to get a timing chain kit because I know those typically need replacing by 70k miles. That'll be a fun weekend. Thanks for the help!