2006 peterbilt 379 with acert motor having power issues

The only sure fire way to test the harness is to totally disconnect it. All injectors, actuators and jake solenoinds need to be disconnected as well as both plugs to the valve cover base. Apply 12 volts to each wire one at a time, then test voltage at the other end with a load on it (load pro test leads or a Powerprobe hook can do this). If you find any wire that drops more than a few 1/10th of a volt when loaded, the harness is junk. There are some common grounds, so you have to check all points on those.

The first thing you should do though is get it hooked up to CatET and see the codes and run the solenoid tests. Flash codes on a cat will only show active codes, so it's not reliable for intermittent problems. You may have more going on than a flash code tells you. It'd be best to get any recent faults diagnosed and clear all faults.

I do think that you have an IVAP sensor issue, but I also think that there is also another issue causing the low power.

 

Most qualified shops can run all sorts of tests in order to locate the problem. The thing is, this is going to cost time and dollar$. You did state this was something you would try to tackle on your own. By knowing the codes displayed you can locate the part/sensor on the motor. Have you check to see if there is any voltage to those parts? Someone stated you could remove that oil sensor and replace the o-ring. This takes about less than ten minutes to perform. Actuator/injector harness mounts into the valve cover plate on the driver side. The actuator pressure sensor and solenoid are on the valve cover plate on the passenger side. Grab a test light or volt meter and probe those wires/connectors. You have to see if these parts are getting power then you go from there.

 

Another thing I forget to mention, it may help, is my Acert doesn't like cold operating temps. Anything around 125 in the winter and it acts funny. I don't get any codes, but I know not to lay into it until I get temp to 150. You say you idle alot, so this may not be the issue by a longshot. Yet, if you are in very cold climates you may choose to purchase a winter front for the grill. Just a thought.

 

I agree with most of what you said, except probing around with a test light. Test lights have no business near electronic engines. A decent multi-meter to test wires that need to be tested is what is needed, never blindly check to see what's there. T-pins are dirt cheap anywhere tey sell sewing suplies and are very good for back probing connectors. Some sensor tests require the sensor to be plugged in while taking measurements, please do not peirce insulation to do this.

Here is the proper instructions on how to diagnose an engine pressure sensor. Sorry I cannot copy the images from cat SIS.


Test Step 1. Determine if the Code is Logged or Active

1. Connect Cat ET to the service tool connector.

1. Restore electrical power to the engine ECM.

1. Monitor the active diagnostic code and the logged diagnostic codes on Cat ET. Note: Wait at least 30 seconds in order for diagnostic codes to become active.

Identify the diagnostic code.
Results:

• Logged code -
  Repair: Do not troubleshoot a logged code unless the code relates to an operator complaint. If the code is logged and the code does not relate to an operator complaint, clear the code.
  If the code is logged and the code relates to an operator complaint, proceed to Test Step 2.
• Active code - Proceed to Test Step 3.

Test Step 2. Check the Integrity of the Connections at the Connectors

1. Turn the keyswitch to the ON position. Do not start the engine.

1. Install a 7X-1708 Multimeter Probe (RED) and a 7X-1709 Multimeter Probe (BLACK) onto the test leads of a multimeter.

1. Check for an intermittent problem at the connector for the suspect sensor:
   Note: Do not disconnect any harness connectors in order to perform this procedure.
   1. Carefully install the spoons (multimeter probes) into the terminal locations for the +5 volt sensor supply and the sensor return at the connector for the suspect sensor.
   1. While you observe the voltage reading on the multimeter, wiggle the wires and pull on the wires at the connector for the suspect sensor. The voltage reading will not vary more than 0.5 volts for a solid electrical connection.
   1. Remove the spoons (multimeter probes) from the connector.

1. Check for an intermittent problem at the ECM connector:
   Note: Do not disconnect any harness connectors in order to perform this procedure.
   1. Carefully install the spoons (multimeter probes) into the terminal locations for the +5 volt sensor supply and the sensor return at the P2 ECM connector.
   1. While you observe the voltage reading on the multimeter, wiggle the wires and pull on the wires for the +5 volt sensor supply and the sensor return at the ECM connector. The voltage reading will not vary more than 0.5 volts for a solid electrical connection.
   1. Remove the spoons (multimeter probes) from the connector.

1. Turn the keyswitch to the OFF position.

Expected Result:
The voltage reading did not vary more than 0.5 volts during either test.
Results:

• OK - The voltage reading did not vary more than 0.5 volts.
  Repair: The connections are OK at the connectors. There does not appear to be an intermittent problem in the circuit at this time. Return the engine to service.
  STOP
• Not OK - The voltage reading varied more than 0.5 volts during the test.
  Repair: Disconnect the suspect connector and inspect the connector and the terminals for moisture, damage, and corrosion. Repair the connectors and/or the terminals. Return the engine to service. STOP

Test Step 3. Check the Supply Voltage at the Sensor Connector
Turn the keyswitch to the ON position. Do not start the engine.
Measure the voltage between terminal A (sensor supply) and terminal B (sensor return) at the harness connector for the sensor that relates to the code.
Expected Result:
The voltage is between 4.5 VDC and 5.5 VDC.
Results:

• OK - The voltage is between 4.5 VDC and 5.5 VDC. The supply voltage is at the sensor connector. Record the voltage measurement. If you are troubleshooting a -3 diagnostic code, proceed to Test Step 4. If you are troubleshooting a -4 diagnostic code, proceed to Test Step 7.
• Not OK - The voltage is less than 4.5 VDC or the voltage is greater than 5.5 VDC.
  Repair: The voltage of the sensor supply is incorrect. Refer to Troubleshooting, "5 Volt Engine Pressure Sensor Supply Circuit - Test". STOP

Test Step 4. Check for Battery Voltage on the Signal Wire
Measure the voltage between the signal terminal and the return terminal on the harness connector for the sensor that relates to the diagnostic code.
Expected Result:
The voltage measurement is less than the +Battery voltage.
Results:

• OK - The voltage measurement is less than the +Battery voltage. The signal wire is not shorted to the +Battery. Proceed to Test Step 5.
• Not OK - The voltage measurement is approximately equal to the +Battery voltage. The signal wire is shorted to the +Battery.
  Repair: Repair the wiring, when possible. Replace parts, if necessary. Verify that the problem is resolved. STOP

Test Step 5. Check the Signal Wire for an Open Circuit

1. Disconnect the sensor that relates to the diagnostic code.

1. Connect a jumper wire between the signal terminal and the return terminal on the harness connector for the sensor that relates to the diagnostic code. This will replace the sensor with a short circuit.

1. Look for a -4 diagnostic code.

Expected Result:
The -3 code does not change to a -4 code when the jumper wire is connected.
Results:

• OK - The -3 code does not change to a -4 code when the jumper wire is connected. Connect the sensor. There is a problem with the wiring harness or with the ECM. Proceed to Test Step 6.
• Not OK - The -3 code changes to a -4 code when the jumper wire is connected. The wiring harness and the ECM are OK.
  Repair: Perform the following procedure:
  1. Remove the jumper wire.
  1. Connect a new sensor to the engine harness. Do not install the sensor into the engine.
  1. Verify that the active -3 diagnostic code does not recur.
  1. Install the sensor into the engine.
  1. Clear all logged diagnostic codes and return the engine to service.
  STOP

Test Step 6. Check the ECM for Proper Operation

1. Determine the P2 signal terminal and the P2 return terminal that relates to the diagnostic code.

1. Remove the signal terminal and the return terminal from the P2 connector.

1. Install a jumper wire into the P2 connector between the signal terminal and the return terminal. This will replace the engine wiring with a short circuit.

1. Look for a -4 diagnostic code.

Expected Result:
A -4 code is active when the jumper wire is installed.
Results:

• OK - A -4 code is active when the jumper wire is installed. The ECM detected the jumper wire at the P2 connector. However, the ECM did not detect the jumper wire at the harness connector for the sensor. There is an open circuit in the wiring.
  Repair: Repair the wiring, when possible. Replace parts, if necessary. Verify that the problem is resolved.
  STOP
• Not OK - A -4 code is not active when the jumper wire is installed. The ECM does not detect the jumper wire at the P2 connector. There is a problem with the ECM.
  Repair: Perform the following procedure:
  1. Restore the P2 wiring to the original configuration.
  1. Temporarily install a test ECM. Refer to Troubleshooting, "Test ECM Mode".
  1. Verify that the problem is resolved.
  1. Install the original ECM and verify that the original problem returns.
  1. If the problem returns with the original ECM, replace the original ECM. Refer to Troubleshooting, "Replacing the ECM".
  STOP

Test Step 7. Check the Signal Wire for a Short Circuit

1. Disconnect the sensor that applies to the -4 diagnostic code.

1. Look for a -3 diagnostic code.

1. Connect the sensor and look for a -4 diagnostic code.

Expected Result:
When the sensor is disconnected, the -4 code remains.
Results:

• OK - When the sensor is disconnected, the -4 code remains. There is a problem with the wiring harness or with the ECM. Proceed to Test Step 8.
• Not OK - When the sensor is disconnected, the -4 code changes to a -3 code. The harness and the ECM are OK. There is a problem with the sensor.
  Repair: Perform the following procedure:
  1. Connect a new sensor to the engine harness. Do not install the sensor into the engine.
  1. Verify that the active -4 diagnostic code does not recur.
  1. Install the sensor into the engine.
  1. Clear all logged diagnostic codes and return the engine to service.
  STOP

Test Step 8. Check the ECM for Proper Operation

1. Determine the P2 signal terminal that relates to the diagnostic code.

1. Remove the signal terminal from the P2 connector.

1. Check if the -4 diagnostic code becomes an active -3 active code.

Expected Result:
A -3 code is active when the signal wire is disconnected from the P2 connector.
Results:

• OK - A -3 code is active when the signal wire is disconnected from the P2 connector. The ECM detected the open circuit at the P2 connector. However, the ECM did not detect the open circuit at the harness connector for the sensor. There is a problem with the wiring between the P2 connector and the harness connector for the sensor. There may be a problem with a connector.
  Repair: Repair the wiring or the connector, when possible. Replace parts, if necessary. Verify that the problem is resolved.
  STOP
• NOt OK - A -3 code is not active when the signal wire is disconnected from the P2 connector. The ECM did not detect the open circuit at the P2 connector. There is a problem with the ECM.
  Repair: Perform the following procedure:
  1. Restore the P2 wiring to the original configuration.
  1. Temporarily install a test ECM. Refer to Troubleshooting, "Test ECM Mode".
  1. Verify that the problem is resolved.
  1. Install the original ECM and verify that the original problem returns.
  1. If the problem returns with the original ECM, replace the original ECM. Refer to Troubleshooting, "Replacing the ECM".
  STOP
  

 

Roger4 on the no test light. I do realize there are proper CAT procedures performed that determine whether a part is deemed good or bad. Yet, I live out in the country. A lot of the work I do is out on farms, produce fileds, then haul it to inner cities. If I get a code on the dash, I crack open my CAT manual in order to correspond code to the part/sensor/ecm connector(pin#s). I turn the key to the on(not running) position and unplug that sensor. I check connector for power. If no power, then I take my allen wrench and disconnect harness at the ecm to see if I have power at the pin or pins. If I have power then I check continuity in the proper lead in question. I use an old Mac multimeter or a Fluke 115. Nutn real fancy. No, I do not hook up to the high voltage components while engine is running. One day I will buy the CAT ET though. Naturally, the test light won't give voltage reading or variances etc, but it gives a starting point.

 

hello i got 04 379 pete have boast problem i can only get 25 lb out if it i look for the boast line on motor can't find them can anyone give idea about what wrong or is that normal boast

 

Type in, "acert low boost" in the search forum. There a several good threads.

 

When is the last time you had the valves adjusted. Also check all your cac hump hoses. You can buy 4 inch pcv plugs drill and tap both ends put a gage in one and the other side put a ball value with a male air line quick connect. Put one of these ends on the last hump hose before the intake pipe. The other one on turbo outlet hump hose and make sure you use a air regulator and put in about 10 psi close the ball value see if it holds. Also check your lines going to air compressor feed from head and small hose from little air box behind fuel filter to the head.