Reduced engine power?

Hello,

The first thing you want to do is to scan and retrieve any trouble code(s). That can help with the diagnostics.
One of the common causes of low power or limp mode is a faulty or dirty throttle actuator. Sometimes simply cleaning out can fix the issue.

Take a look at this helpful guide:

https://www.2carpros.com/articles/reduced-power-limp-mode

Let me know what codes are showing or if you have any questions.
Thank you.

Hi,

First, we need to scan the computer for diagnostic trouble codes. In this case, you already replaced the accelerator pedal position sensor and that didn't change it. So, it could be a variety of other causes. For example, oil pressure, temperature, throttle body, and so on.

In this case, I would rather have the can-bus scanned if possible. CAN stands for controller area network. Basically, the different computers/modules are tied together via a few wires. This type of scan will retrieve codes regardless of the module storing them.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

If that isn't an option, use a traditional scan tool to see if there are any codes that may be relevant and point us in the right direction.

Let me know.

Take care,

Joe

Hi,

Two of the codes are specific to the heated O2 sensors. I don't feel that would put it in limp mode, but the U0107 indicates the ECM is not receiving or transmitting messages on the CAN bus related to the electronic throttle control system. That would place it in limp mode.

There are two primary components, the throttle actuator control motor and the accelerator pedal position sensor. I will tell you that it isn't uncommon for the electronic throttle body to fail and need to be replaced.

Here is what to start with. First, locate the accelerator position sensor on the throttle pedal and inspect the electrical connector for tightness, corrosion, or any wire damage. See pic 1.

If that appears good, go to the throttle body and do the same.

Let me know what you find. Also, make sure to clean any dirty connections. It may be a good idea to apply dielectric grease at the connections.

Take care,

Joe

See pic below.

Hi,

Two of the codes are specific to the heated O2 sensors. I don't feel that would put it in limp mode, but the U0107 indicates the ECM is not receiving or transmitting messages on the CAN bus related to the electronic throttle control system. That would place it in limp mode.

There are two primary components, the throttle actuator control motor and the accelerator pedal position sensor. I will tell you that it isn't uncommon for the electronic throttle body to fail and need to be replaced.

Here is what to start with. First, locate the accelerator position sensor on the throttle pedal and inspect the electrical connector for tightness, corrosion, or any wire damage. See pic 1.

If that appears good, go to the throttle body and do the same.

Let me know what you find. Also, make sure to clean any dirty connections. It may be a good idea to apply dielectric grease at the connections.

Take care,

Joe

See pic below

Hi,

I have a feeling it is the throttle body. However, that is a theory at this point. By chance, have you checked the connectors to make sure there isn't an issue?

Let me know which engine you have in it so I can get the right directions and schematics.

Take care,

Joe

At the throttle body, the connector will have yellow and brown wire. Inspect them to make sure they are not damaged, or the connector isn't loose, corroded, or has a damaged pin.

See pic below.

Take care and let me know what you find.

Joe

Hi,

If the U0107 is still present, we still have an issue within the can bus system. I need confirmation of the exact engine size. I realize it is a V8, but there are three options.

Let me know that so I can dig deeper.

Take care,

Joe

Okay.

Here is where I want to start: First, I want to supply a new ground between the battery negative and the throttle control module. It should be on the firewall, under the hood, and on the driver's side.

Get a good copper wire to do this. I would say approximately 10-gauge wire. Remove one of the bolts on the throttle control module, clean it with sandpaper, and then reattach it.

From the module, I want you to make another ground to a place on the engine block. You can do this at any convenient spot on the engine block. Just make sure it is a clean connection and keep it away from the exhaust or anything that can cause the insulation to melt.

From the engine block, I want you to run another ground jumper wire to the powertrain control module. Do the same here. Remove one of the mounting bolts, clean the metal with something like sandpaper, and attach the ground on the PCM mounting bolt.

I realize this may seem confusing, but it's really simple. In general, you are making three ground wires that start at the battery, go to the throttle module, then to the engine block, and then to the PCM.

The 4.8L engine block has a ground strap that runs to the firewall. It is basically impossible to access where it mounts on the engine, but they are known to fail there. I have a feeling we are having a voltage loss.

Let me know if this makes sense. LOL

Take care,

Joe