HELP!!! Turbo problem??? Loss of power at low rpms.

[cartmanea]

Ok, weird symptoms here, seems like maybe the turbo is stuck in the high rpm position, but please give input. So, here's the story. 2003 F250 6.0L Torqshift with 71k miles and only thing that its had done until now is the ICP sensor. Truck was totalled, hit front left corner last February. I bought it in June and just finished rebuilding it. It has fresh fluids in everything. The truck is absolutely GUTLESS at anything under about 2750 rpms. Idles great, sounds great, just won't GO! It acts like the throttle isn't opened up, but the shift points are where they would be for wide open throttle, it just takes a lot longer to climb rpms between shifts. When it gets to about 3000 rpms, it absolutely takes off like a bat out of hell! It feels like it will almost break the tires loose at that point and from 3000rpms on up it runs just like my dad's 6.0L. My thought is the turbo is stuck in the high rpm position so it has no boost at low rpms, robbing power. Could this be true or is it a sensor, servo, something else that could be causing the problem? The CEL is not on, however the ABS light and airbag light are on for other reasons. Please give me input! Thanks!

[brickie]

Vgt actuator is the first thing I would check.Next is a turbo cleaning.

[cartmanea]

Also, I just made a 300 mile all highway trip. First half was rolling hills, 55-65mph. I would have to stuff my foot in it and shift it down to not lose speed on hills, and I got 11mpg for the first 150 miles. Second half was mostly flat, running 70-75mph so the rpms stayed over 2000, got 21mpg!!! This is really weird. I think the higher rpm leg of the trip was better mileage because I had it up where the turbo was boosting instead of the low rpm stuff before where it may have been causing more restriction than natural aspiration...

[cartmanea]

Is there a way to check the VGT actuator other than replacing it?

[brickie]

I am not sure.It is opperated on the low pressure oil system so if there is varinsh deposits on the plunger it may stick.Pull it out and see how well the plunger moves would be the only way I could think to check it.

[cartmanea]

I read in the ford service manual on this. They do a test where they set turbo levels with a computer and watch the actuator control signal with a test light. 0% and the bulb is out, 80% and the bulb lights up. It is a variable voltage signal that controls it. Seems like I can put a test light on it and watch the light to make sure the PCM is sending the control signal, if it is then I try a new actuator. If that doesn't fix it then I need to clean the turbo

[cartmanea]

Ouch, just checked with directfordparts.com, a new actuator runs $248.

[tippmann87]

Originally Posted by cartmanea

Ouch, just checked with directfordparts.com, a new actuator runs $248.

When you think about it, $248 isn't too bad....There are plenty of other parts to go that could cost you over 1k....just tryin to make you feel better

[ozx3+1]

Have a look at the attachment to this post for the troubleshooting guide. I hope this attach thing works this time!

[ozx3+1]

AK2 DIAGNOSTIC TROUBLE CODE (DTC) P0046

• Possible causes:
  • control circuit open
  • control circuit shorted to voltage
  • control circuit shorted to ground
  • VGT actuator
  • PCM.
• Key off.
• Disconnect the VGT actuator electrical connector.
• Key on.
• Measure the voltage between the VGT electrical connector pin 1 and ground.

Is the voltage greater than 11.0 volts?

Yes	No
GO to AK3	REPAIR open in circuit. RESTORE the vehicle. CLEAR DTCs and RETEST the system.

AK3 CHECK VGT ACTUATOR

• Key off.
• Enter output state control.
• Install a test light between the VGT electrical connector pins 1 and 2, harness side.
• Key on.
• Access VGT PIDS.
• Command VGT to below 10% duty cycle.
• Command the VGT to 85% duty cycle.

Does the test light go out as VGT duty cycle is driven low and lights as the duty cycle is driven high?

Yes	No
GO to AK7	GO to AK4 .

AK7 CLEAN THE VGT ACTUATOR VALVE AND RETEST

CAUTION: The VGT actuator valve is sensitive to contamination. All work areas must be clean before starting this procedure. Do not allow contamination to enter the valve ports, cam follower, or turbocharger housing. Handle the VGT actuator by the solenoid body only. Do not attempt to wipe oil off the valve. Do not let the valve come in contact with materials that could contaminate the valve mechanism

• 
  
  
  
  
  
  CAUTION: Use only the Carburetor Tune-Up Cleaner PM-2 to spray the actuator valve. Brake cleaner or other solvents may damage the actuator valve.

• Remove the VGT actuator from the turbocharger assembly. Note: Do not spray the zinc coated larger diameter housing, or electrical connector.
• Spray the valve with Carburetor Tune-Up Cleaner PM-2 while pressing the cam follower (tip of the actuator).
• Install the VGT actuator and connect the VGT connector.
• Key ON, engine running.
• Access the output state control.
• Access the VGT PID.
• Increase the commanded engine speed to 1,250 RPM using output state control. The calibration may limit the actual RPM between 1,150 and 1,200 RPM.
• Increase the VGT duty cycle to greater than 70%.
• Decrease the VGT duty cycle to 0%.

Does the turbocharger pitch change when the VGT duty cycle is increased and decreased?

Yes	No
The system is operating correctly at this time. The concern may have been caused by a contaminated VGT actuator valve. CHANGE the oil and oil filter assembly.	INSTALL a new VGT actuator. CLEAR the DTCs. REPEAT the self-test.

AK4 CHECK VGT CONTROL CIRCUIT FOR A SHORT TO VOLTAGE

• Key off.
• Remove the test light.
• Disconnect the PCM engine harness electrical connector.
• Key on.
• Measure the voltage between the VGT actuator harness connector pin 2 and ground.

Is the voltage less than 0.2 volts?

Yes	No
GO to AK5 .	REPAIR short in control circuit. RESTORE the vehicle. CLEAR DTCs and RETEST the system.

AK5 CHECK VGT CONTROL CIRCUIT FOR A SHORT TO GROUND

• Key off.
• Measure the resistance between VGT actuator connector pin 2 and ground.

Is the resistance greater than 10,000 ohms?

Yes	No
GO to AK6 .	REPAIR short in control circuit. RESTORE the vehicle. CLEAR DTCs and RETEST the system.

AK6 CHECK VGT CONTROL CIRCUIT FOR AN OPEN

• Measure the resistance between the VGT actuator connector pin 2 and PCM connector pin 10.

Is the resistance less than 5 ohms?

Yes	No
REPLACE the PCM.	REPAIR open in control circuit. RESTORE the vehicle. CLEAR DTCs and RETEST the system.

[denman81]

if the trubo has been sitting since june id say your vanes are rusted up. Tear her apart and clean her. you see this off the lot if a truck sits for a couple of weeks, and yours has been sitting for 8 months...... Id say it just needs a cleaning. thats a cheeper fix compared to the actuator. and if the actuator worked when it was in an accident, it should be just fine when you restarted it after you fix it. Good luck! let us know what you find out.

[denman81]

awsome write up oz! good info!

[ozx3+1]

Originally Posted by denman81

awsome write up oz! good info!

Thanks, it's my pleasure...

[3000 FPS]

Originally Posted by denman81

if the trubo has been sitting since june id say your vanes are rusted up. Tear her apart and clean her. you see this off the lot if a truck sits for a couple of weeks, and yours has been sitting for 8 months...... Id say it just needs a cleaning. thats a cheeper fix compared to the actuator. and if the actuator worked when it was in an accident, it should be just fine when you restarted it after you fix it. Good luck! let us know what you find out.

I think denman81 has it right if the turbo has been sitting for a long time it is probably stuck. The unison ring in the turbo will not rust because it is non magnetic I checked mine. The vains themselves are just slightly magnetic but the housing will rust like a son of gun and that is where the vains lay against.
Also any soot that is in there will have a tendency to dry and stick in place. I would clean the turbo.

[brickie]

Thanks OZ! I love FTE. I learn more everyday on the 6.0 through this fourm.