183K miles. Started having poor acceleration, poor responsiveness, and the occasional stalling after starts. Decided to replace the ignition coils since they’ve never been changed (plugs done at 153K miles). Bought NGK ignition coils off RockAuto, and decided to do the work myself. While I was at it, I also cleaned the throttle body, replaced the air filter and a bunch of small hoses connected to solenoids and the intake manifold that were cracked/damaged.



Car fired right up and drove beautifully for about a week before it started randomly hesitating/stuttering/jerking (h/s/j). No check engine, and no codes. The h/s/j happens after the car is warmed up, and is fairly random (some drives it doesn’t happen at all, and it seems to happen most often when I’ve driven it on the highway for a period of time). When it happens, it’s usually under low-medium acceleration.



Re-examined my work and found the PCV valve upper hose clamp wasn’t in the right place so I readjusted the clamp. Drove fine for another week before the h/s/j returned. The hose was already looking old/bloated so I decided to replace the hose. Drove fine for a couple of days before h/s/jerking returned.



Took it to my local mechanic who I trust, and he replaced my PCV valve because it wasn’t the right size (I bought mine from O’Reillys, and the threaded end was 1mm too small). Drove fine for a couple of days before hesitating and stuttering again, but not as strongly. Took it back to my mechanic again and had him just take the intake manifold off again to check my work, thinking I must have reassembled something wrong. He replaced the spark plugs (at my request so that I could rule that out), throttle body gasket (which was brittle and had weak points) and intake manifold gasket (which also was brittle and hardened). I barely drove it an hour after all that work before the hesitating and stuttering resumed. Still random, and still no check engine light or codes.



I’m at a loss for what the problem is at this point. I’ve clearly exchanged one problem for another, but honestly the car drives so much better when it’s not hesitating or stuttering.



Any ideas what this could be?

 

It is quite challenging to diagnose hesitation when there is no codes. Given what you’ve already done, the next area to investigate is a failing MAF sensor.

 

I just tried cleaning the sensor. Will report back if it fixed the issue. If I do need to replace it, would the Hitachi sensor off Rock Auto be the OEM replacement?

 

If the MAF sensor is defective, you can't just clean it. Looks like a Hitachi MAF sensor from Rockauto for your car is only $65. If you are short on cash, you can get a generic MAF from Amazon for about $25. Hitachi has a long life but more $$$. It all depends on how much $ and time you want to spend on messing with your car.

 

Replaced the MAF with Hitachi off Rock Auto and the issues still exist. Could it be a fuel pump or injectors?

 

hey man. Sounds like exactly what mine did around that mileage. Would only happen AFTER the CVT fluid is warmed up. Would barely go after sitting at a red light. Anyway, I did a drain and fill on the CVT fluid. Fixed the issue after the first one, but I did another after 1k miles after the initial drain and fill. Obviously, old fluid was my issue, and I suspect the same for you.

 

if its not rough idleing then its a transimison proplem cvt oil need to be changed every 30k or so