2018+ Mustang GT overlap tune: VCT Disabled Issue

[blackbolt22]

Hello,

Have any of you successfully done an overlap tune on 2018+ Mustang Auto? Had any issues where the VCT goes Disabled then back to Optimal Stability in a weird cycle with any significant overlap angles (like 0/20 spread?).

Any time I put any significant overlap into the car at idle it keeps triggering a cycle where it goes disabled, back and forth. All of the appropriate settings are present and I've tried over the course of my friend visiting a lot more than just the normal must have changes. I've never experienced this behavior on my 2014.

Finally I tried even the most basic of changes just to get the angles in ( and allow these angles at idle rpms ), and it still occurs. If there is any sort of decent overlap it freaks out.

Here's 2 log files. First one shows a startup and a lot of disables.
Second one shows a disable occurring even in Emissions Reduction mode. In these files I'm using -5/15 but I've tried lots of various angles including stock ones like MP8/MP9 and my own custom ones in MP1/2. More overlap = more disable frequency.

20-12-13 14-23-47-Disables.hpl
20-12-13 14-52-04-Disable in ER.hpl

[Vaderperformance]

my gt350 disables at WOT i havent been able to figure it out..

but here is a video of idle issue vct loosing phasing/disabling


https://youtu.be/yij4042WNQ4

[blackbolt22]

my gt350 disables at WOT i havent been able to figure it out..

but here is a video of idle issue vct loosing phasing/disabling


https://youtu.be/yij4042WNQ4

Watching right now! Wanna know what's crazy? Yesterday my friend's car said it needed an oil change when I was datalogging it to find out why it was idling erratically/killing like this.

A couple months ago I sent him on his way and it had no issues with a small overlap tune but did with a larger overlap (the same vct disable issue). He bought the car in May and it took me a few months to want to tune it for him. I know he's never done an oil change...

Recently though he told me it had started killing while idling in park. I figured it was because of the colder weather we have here and that the engine was cold, and an overlap tune would be harder but he was like nah it works fine when cold but once he drives for a while and stops, sits at idle in park (like lunch break at work), it starts doing it.

---------------------------------

If it's the oil then my theory is: The ECM is pressure checking the VCT system and disables below X psi. At idle with thin oil (due to old or hot), pushing high cam angles for overlap causing more of a pressure drop under the threshold for the oil pressure. When VCT is disabled the phasers go back to home briefly causing it to quickly regain the needed pressure to re-enable and continuing the cycle of enable/disable.

When I tried 0/10 it didn't happen but 0/20 did. This has got to be the problem! It just makes too much sense with the behavior I'm seeing and how when I use a large angle (mostly with exhaust cam) it starts glitching out!

So what's the 'easiest' overlap angles that will use the least pressure at idle.. That's probably the solution + an oil change. lol

[murfie]

Watching right now! Wanna know what's crazy? Yesterday my friend's car said it needed an oil change when I was datalogging it to find out why it was idling erratically/killing like this.

A couple months ago I sent him on his way and it had no issues with a small overlap tune but did with a larger overlap (the same vct disable issue). He bought the car in May and it took me a few months to want to tune it for him. I know he's never done an oil change...

Recently though he told me it had started killing while idling in park. I figured it was because of the colder weather we have here and that the engine was cold, and an overlap tune would be harder but he was like nah it works fine when cold but once he drives for a while and stops, sits at idle in park (like lunch break at work), it starts doing it.

---------------------------------

If it's the oil then my theory is: The ECM is pressure checking the VCT system and disables below X psi. At idle with thin oil (due to old or hot), pushing high cam angles for overlap causing more of a pressure drop under the threshold for the oil pressure. When VCT is disabled the phasers go back to home briefly causing it to quickly regain the needed pressure to re-enable and continuing the cycle of enable/disable.

When I tried 0/10 it didn't happen but 0/20 did. This has got to be the problem! It just makes too much sense with the behavior I'm seeing and how when I use a large angle (mostly with exhaust cam) it starts glitching out!

So what's the 'easiest' overlap angles that will use the least pressure at idle.. That's probably the solution + an oil change. lol

The position of least resistance is advanced, going with the pull of the timing chains. 0 for exhaust, highest negative for intake.

Retarded is fighting against the direction the chains are pulling the cams.

The intake cams retard at idle, nearly as far as they will go. The mid lock phaser makes it's starting point closer to desired idle position.