Exhaust Valve Modification for 5VZ-FE
The 5VZ-FE variants of the 90 series came with an exhaust valve from factory which was presumably designed to quieten the exhaust at low rpm. Considering the age of our vehicles, it's not uncommon for the exhaust valve to be stuck. If stuck in the closed position, the valve can restrict exhaust flow which theoretically will run inefficiently, making the car run low on power and sound terrible. Aftermarket mufflers do away with the valve, so it's not necessary for the operation of the vehicle.
Detailed below is a quick and easy method to modify the valve to allow the exhaust gases to pass through freely. It's possible to completely remove the valve mechanism, but I believe the marginal obstruction caused by the pin and the housing wasn't really worth the effort of cutting a metal plate and sealing to patch the hole where the mechanism would sit.
**_DISCLAIMER: The studs can be brittle due to their age and the condition they're in. If you break the studs, it's not possible to replace them! You will have to replace the muffler completely, or Macguyver a way to seal the muffler again.
_**Time required: 15-30 minutes
Tools required:
- Penetrating Oil / Lube
- Socket Set (10 & 12mm)
- Flat Screwdriver / Pry bar
- Drill with drill bits
- Exhaust safe gasket (maybe)
****NOTE: Looking back after some feedback from some other members, I've over-complicated the process! Don't bother drilling out the flap, just remove the whole mechanism/housing/plate all together and just chuck the cover plate back on.
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To make life easier, spray down the nuts with penetrating oil. I sprayed the nuts immediately after driving the car, and waited for the car to cool down before removing the 6x nuts.
Remove the cover plate to expose the valve mechanism.
![]- Use a pry bar / flat screwdriver to remove the valve mechanism housing from the muffler. If you are gentle/lucky enough, you might be able to reuse the gasket. Notice that the screws (in my instance) had been tacked to the pin, so it wasn't possible to unscrew them.
- Use a drill with varying drill bits (going from small to large) and drill away the head. Eventually the flap will loosen.
- Remove the flap and reinstall the mechanism/housing in reverse order. Use suitable exhaust gasket if the original gasket is too damaged. Tighten till fairly tight, but don't over do it.
- Enjoy that deeper low end exhaust note
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