Hello again VR4 community,

Need help figuring out what’s causing my VR4 to start to vibrate at around 4-5k RPM range?

This issue arise after timing belt / water pump service done at a local shop. Car drives fine under 4k rpm BUT starts to vibrate after that. I returned the car back to the shop and explained to him the issue. He took another 2 days with the car and still can’t figure out the source of the issue. He initially thought it might be the motor mounts, not the case.

Any advice or recommendations will greatly be appreciated.

Thanks in advance

Step 21. click

They didn't know to set the balance shafts in the first place? If they don't take responsibility for this, I would certainly look for someone more qualified to do repairs in the future. Even then I'd probably still think twice about continued business with this mechanic.

the funny thing is, when you have this vibration, it's almost always the rear shaft (oil pump) not the front shaft that's out of phase, since that mark is so obvious.

Since the oil pump can be 360* out of phase, it can look lined up and still be totally wrong. Take the plug off and check it with a screwdriver per the vfaq. You can probably get the car on a stand, and check that with ~15 minutes of work.

With the car warmed up and the timing ground set you could try adjusting the idle set screw in the throttle body. Look at the manual for further details.