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VCT Causing stalling FG


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Currently having issues with a customers FG XR6T Ute. The vehicle came in with a issue of stalling once at operating temperature.

After many tests and data logging it has been determined that the issue is caused by the vct advancing and retarding the cams beyond a stable condition. These conditions have created and overlap of 60 degrees. After reaching operating temp if the vehicle comes to an idle condition it immediately stalls and will not start without unplugging the vct solenoids. Now interestingly enough the vehicle runs brilliant under any load or power conditions. Can cruise on the highway without any cam angle errors. As soon as you pull up, cam angle errors on both cams.

Now before we get too carried away I will list the solutions and tests I have conducted.

  • Read the codes using Forscan, Launch and Snapon scanners, codes are - P1383-00 and P1381-00
  • Replaced VCT solenoids
  • Replaced VCT cam angle sensors
  • Replaced VCT cam gears
  • Replaced the cams themselves
  • Checked cam craddles and oil passages
  • Checked oil pressure
  • Changed Ecus and tunes, strategies etc
  • Disabled VCT control at rpms bellow 2000rpm
  • Raised airflow at idle
  • Raised idle rpm to 1000rpm
  • Checked voltage at the vct solenoid plugs and at the ecu. Approx 4.5v before the issue and 12v+ once the issue occurs
  • Checked and added engine earthing points
  • Checked fuel trims stft and ltft.

I'm stumped at this point. I've tried and looked at anything surround this issue

 

Here is the log from last run, also a screenshot.

 

If anyone could throw their 2 cents worth, Would be great thanks you.

New Bitmap image.jpg

30-08-2022 06-16-08 PM Log.teclog

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12 minutes ago, Roland@pcmtec said:

Have you put a completely stock tune in the car? 

Do you have a spare pcm? 

Also have you checked the cam timing itself hasn't skipped a tooth? 

Standard valve springs? 

You've tested everything id recommend otherwise. 

Yes tried stock tune just with injectors scaled in. 

Have also tried 2 other pcms, all with either current tune or with different strategies.

 

Cam timing checked multiple times, has brand new crow cams springs. Like to note it runs without fault for approx 20 mins.

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Wiring.

 

 

4.5V before issue and 12V after issue happens (operating temp) Is a this a signal wire into the PCM from the Cam Angle Sensors? if so I don't think a signal wire is meant to be 12V for an ecu. I would check every wire on the PCM plug for shorts to a 12v power source. What gets 12V at operating temp? Cooling fans do, might be something to check.

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The solenoids are PWM so you'll be seeing an average voltage on a multimeter. I'm not sure what 100 the peak amplitude voltage is however being a fairly hefty actuator 12v doesn't sound out of the realms. Depends if the driver is in the pcm or external and it is just a signal wire, wiring diagram would confirm. If it's external and the pcm output is a low load control output then I agree 5v is what I'd expect to see as the max voltage. Also depends where you are measuring the voltage. 

12v should match 100% duty cycle with 4.5 being approx 30% duty cycle. If you have a proper scope set it to measure pulse width and check if it matches the datalogger value. 

A short is possible but it's fairly normal to see 100% duty when the actuator fails and the pcm cant obtain the required angle. 

Im pretty sure you can put vct into test mode and 0, 25,50,100% duty to verify this. 

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On 8/30/2022 at 6:41 AM, Roland@pcmtec said:

Is the intake and exhaust wired back to front? 

Try locking the cams in software and see if they do what you tell them to. 

Edit:

Could be this. As those DTC from your scan tool reference the following:

1381 P1381 Camshaft Position Timing Over Advanced (Bank 1)
     
1383 P1383 Camshaft Position Timing Over Retarded (Bank 1)

 

   

But they do not error for the following:

1380 P1380 Camshaft Position Actuator Circuit (Bank 1)
     
1382 P1382 Camshaft Position Timing Solenoid #1 Circuit
     
1384 P1384 Variable Valve Timing Solenoid A Circuit
     
Edited by jakka351
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