Gen 2 Prius 50MPH+ rough running. Timing chain?
Hi, I have a 2007 Prius touring with 201K miles. Over the last year I've thrown parts at it and I've gotten it to run better but it still feels like the engine struggles over 50mph. It gets about 42-45 mpg when kept at about 50-55. But once I hop on the freeway anything above 60mph and MPG drops to low to mid 30s. The motor doesnt seem to settle down into the right gear to maintain 65-70. I was just visiting my mom and she has a 2006 with 165K miles and I drove it on the freeway and it is so much smoother and the balance between electric motor and gas engine is great. My car engine sounds louder and I can feel a slight vibration in the accelerator.
My prius has new plugs, coils, injectors, MAS air sensor, throttle body, VVT solenoid and CAT. I've unplugged the battery and reset the ECU after any time I've worked on the car. It doesn't throw any codes but I wonder if the timing chain is stretch or the tensioner is maxed. Or is the VVT system not fucioninng properly. Is there any way to test or check without removing valve covers and really getting in there. could any sort of diagnostic tool test or check this?