VCT mode “disabled”

[engineermike]

Anyone experience this and what are all possible causes?  No DTC, just VCT disabled when it shouldn’t be.

[Roland@pcmtec]

What is your oil and coolant temp reading?

[engineermike]

Coolant temp is 185 F.  Oil temp when it does it is around 190 F.  The issue seems to stop around 210 F.

[Roland@pcmtec]

Is this a new issue or a specific car? 

[engineermike]

I just noticed it on my own car.  I’ve searched parameters, channels, and read the ford obd diagnostic manual and can’t seem to correlate what causes “vct disabled” beyond inadequate oil pressure.

[Roland@pcmtec]

So your cams are locked and not moving? 

[engineermike]

It only happens at high rpm/wot, intermittently, and seems to resolve when the oil is hot.  Everything works fine until vct schedule switches to “disabled” which sends all cams to 0,0.  I just don’t know the possible reasons the logic would decide to do that. 

Edited September 10, 2023 by engineermike

[Roland@pcmtec]

Are you seeing high duty cycle or high cam error just before this happens? If the cams go out of range you will get cam fault but it will clear so fast it won't log a DTC. 

Try "locking" the cams at some degree and see if it goes away, this is likely a mechanical issue. 

Do you have upgraded valve springs or any modifications to the head? 

[K44]

Mike, have you figured this out?

[Roland@pcmtec]

I spoke to him and they have upgraded the dfi pump and its likely changed the mechanical properties of the actuator due to oil pressure or load somewhere else causing it to go out of bounds enough to go into fault mode. 

I'm not sure if he found the limits for the fault bounds to increase them and bandaid the issue. 

[engineermike]

I made progress but not solved yet.  The question in my mind was, is the EOT value causing this or the actual EOT?  Someone else had the idea to "fool" it to believe a different temp to see if the problem followed the temp reported to the PCM or the actual temp.  I found auf60084 and learned if you put a smaller value in, it will report lower EOT.  When I did this, I found the "VCT disabled" issue tracked with the actual oil temp, not the inferred temp.  In other words, after the engine oil was good and hot it did not have the issue even if the reported EOT was 150 or below.  Therefore, it's not some EOT vs XYZ table in the calibration doing it.  It leads me to conclude the problem is physical in nature and the PCM is seeing something it doesn't like and disables VCT as FMEM of sorts.  

Being a physical problem, I've compared a ton of logs and observed that the cam angle, angle error, and phaser duty cycle do not seem to correlate to the disabled issue.  I'm thinking in the direction of cam-to-crank reluctor diagnostics but can't get my head around how this might be affected by oil temp or viscosity when the phaser and solenoid seem to be working properly at the time.

Edited September 22, 2023 by engineermike