The Difference Between a Cam Phaser Lockout and a Cam Phaser Limiter

Some people think that locking out your cam phaser and installing a cam phaser limiter is the same thing. That's actually a misconception. Installing a cam phaser limiter when you should really be locking the cam phaser into place can cause further damage to the engine.

We’re here to clear up this common misconception by explaining the difference between the two similar parts.

What is a Cam Phaser Lockout?

Lockout explained

A cam phaser lockout is a wedge that basically prevents the variable cam timing (VCT) system from shifting out of the 'advanced' timing mode. The cam phaser is essentially locked into place and cannot move at all.

What is a Cam Phaser Limiter?

A VCT (variable cam timing) cam phaser limiter is basically an undersized lockout that allows for some timing changes. The limiter is designed to restrict the range of the cam movement to 20 degrees or so.

The Difference Between the Two

What is the difference between a cam phaser lockout and a cam phaser limiter? A lockout doesn’t allow the cam phaser to move at all. The limiter allows a limited range of movement as compared to stock.

Both parts serve different roles, too.

Lockout installed

A cam phaser lockout is designed to solve the problems caused by a broken cam phaser: excessive noise and the potential for long-term damage. A cam phaser lockout kit (like this Forbidden Diesel lockout kit for 5.4L and 4.6L Ford 3 valve engines) contains a precisely machined metal block that is inserted between two of the vanes in order to lock the cam into the advanced timing position. (Read more here about how a cam phaser lockout kit works). You’re not required to reprogram the ECU after installing a lockout, but it’s highly recommended.

A cam phaser limiter is used for performance applications, not for fixing a noisy cam phaser. It’s designed to replace the cam phaser’s factory back-plate. The limiter prevents the valves from hitting the pistonswhen performance cams are used. You’re required to reprogram the ECU after installing a limiter.

In a nutshell:

  1. Lock out your cam phaser if it’s broken. A cam phaser lockout kit is a permanent repair for this problem. If you install a limiter into a broken and noisy cam phaser, it will still make noise. At some point, the phaser will fail and then there's risk of engine damage.
  2. Use a cam phaser limiter if you want to use an aftermarket cam in order to increase your engine’s performance. A cam lockout doesn't allow for any cam timing variability. Timing variability is needed when using a high performance cam.

Got any questions about how these two parts differ from each other? Feel free to contact us. We'll be happy to discuss these parts with you!