Ask The Experts: Actuator Not Moving? Engine Losing Power? Common VGT Turbo Questions

Today, we're taking a look at some of your questions from YouTube relating to issues with your Variable Geometry Turbochargers.

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Diesel VGT Actuator Not Moving

One question comes to us from a user who asks: "My actuator is completely free when taken apart. I put it back together and it will not move at all. What is going on? Is the nozzle not properly lined up with the shroud? Is my turbo bad?"

2 Main Components Of Variable Geometry Turbo 

It's important to note that on VGT turbos you have a couple different components.

One is the electronic portion of the turbo, and that includes your actuator. Then you have the mechanical portion inside the turbo. This includes your vanes and shroud plate.

Default Codes? 

Typically, if your actuator is bad, you're going to have fault codes relating to your actuator. It's an electronic device, so you're going to have an electronic feedback to the ECM letting you know what's bad. 

Based on the info we have, this sounds like an issue with the mechanical portion of the turbo, your vanes and shroud plate. If your vanes have any type of debris on them or are bent at all, the vanes will have a hard time traveling through the shroud plate. 

Try This...

You could try taking off the shroud plate with the exhaust housing, which is absolutely going to free up your vanes to move in and out freely because they're not trying to get through the shroud plate. So, this could help you identify whether you're looking at damaged vanes causing your turbo to malfunction.

Engine Losing Power? It Might Be Your Actuator

Another commenter writes: "I have a 2015 Kenworth with a Paccar MX 13 engine. All of a sudden it loses power for a little bit and comes back again. On the computer, it says data erratic and sometimes it says VGT Actuator 1. What do you guys think?"


its Either Electrical or Mechanical

We'd probably break this down into two possibilities. Again, you could have a mechanical problem or an electrical problem. The trick is to take the code you're getting and determine if it's referring to an electrical problem or a mechanical problem. We just don't have enough information here to determine exactly what it is.

Check your ECM Voltage 

On your turbocharger, you've got an ECM that's controlling an actuator. That ECM sends a signal out to your actuator, telling it things like: "Hey, the engine needs more air, so you need to move." Then it gets a reference back. If it sends 5 volts out and it's supposed to move 30 degrees, then it's supposed to get something like 3 volts back. If it only gets 1 or 2 volts back, your computer will throw a code saying it's not moving where it's supposed to be.

Or you could have something going on mechanically. So, something in the turbo might be binding or locking up, and your ECM is telling it where it needs to be, but it can't get there physically because of carbon in the system, bent fins in the actuator, or whatever it may be. So we really need to break this problem down and determine if it's mechanical or electrical.

Get Your Fault Code 

You can probably take that system, get your fault code, and figure out what's going on there. If you have an electrical problem, it could be wiring, it could be a short circuit in the system, or it could be wires rubbed through. If it's mechanical, you may have a broken component, binding, or sticking.

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