VIBRATION/SHAKING IN 1400 RPM

[removebeforeflight1994]

Hello everyone,

I own a 2012 Toyota Yaris, 1.0 manual, currently at 164,000 km. I bought the car about 7 years ago when it had 38,000 km on the clock.

To put it briefly, ever since I bought it there’s been a noticeable vibration around 1,350–1,450 rpm. Outside of that range, there’s absolutely no vibration at all.

When the engine revs slowly, or if I hold it right at 1,400 rpm, the vibration becomes strong enough to noticeably shake the body of the car. But if I accelerate quickly and the revs pass through 1,400 rpm, I only get a short “zzzzzsstttt” sound along with a slight vibration.

This happens regardless of whether the car is in gear or not: while idling, coasting downhill, or accelerating uphill—it’s always the same as long as the revs are between 1,350 and 1,450 rpm.

Many mechanics have looked at it over the years. We all agree the vibration is real, but every part that could potentially be causing it appears to be fine, so we haven’t been able to find the source.

Throttle body was cleaned

Spark plugs replaced

Injectors checked

Engine and gearbox mounts inspected

Car hooked up to OBD—everything within normal parameters

Clutch was replaced at 90,000 km due to gear-shifting issues, but it didn’t affect the vibration

I’d be very grateful to hear from anyone who has experienced something similar with their Yaris, or who might have an idea of what the cause could be.