L96 Variable Cam Timing

[Dutch]

Buggy with stock L96, custom ground cam, ECM from a 2012 Silverado 2500.

Trying to implement the following WOT/High Baro VCT profile into a E38 ECM:

RPM	Desired Cam Position
500	3 Advanced
1000	3 Advanced
1500	2 Advanced
2000	1 Advanced
2500	1 Advanced
3000	0
3500	0
4000	0
4500	2 Retarded
5000	4 Retarded
5500	6 Retarded
6000	7 Retarded

(EDIT: the cam is installed "straight up", 0 degrees)

Are the positive values in the cam tables quarter degrees retarded? ("20" = 5 Degrees Retard, "-12" = 3 Degrees Advanced?)
I have validated there is enough piston/valve clearance for the above profile.

Thanks!

[GHuggins]

You need to post the tune, but pretty much and positive value for a cam position is retarded, so if you put in a 1 or .5 or whatever it's that many degrees retarded at that load and rpm. Even on their dual overhead setups I've not known them to allow advance. That should have been designed into the cam to begin with then retarded from there.

[Dutch]

Attached is the stock tune of a 2013 Silverado because the tune itself is irrelevant -
I'm asking how the ECM interprets the cam position values. I do not believe they are 1:1 because the factory values do not make sense in that regard:
Screenshot 2023-11-10 185103.png


I remember someone explaining to me that positive values are quarter degrees retarded, negative values are quarter degrees advanced.
This makes sense given most stock reads I've seen, however it does not accept negative values:
Screenshot 2023-11-10 185613.png

Hence why I'm asking for confirmation to save time on the implementation:

- What do the numbers in the table represent? Quarter degrees, Half degrees, mechanical steps in the phaser, etc?
- Do the factory L96 cam phasers not support advancing the cam?
I (foolishly) installed the cam straight up assuming I had freedom to advance the cam with VCT.

Thanks!
chevy-silverado2500-2013-6.0-oem.hpt

[2xLS1]

8 = 0 advance or retard. Numbers smaller than 8, subtract that number from 8, that is the number of degrees advanced. Numbers larger than 8, subtract 8 from that number and that is the number of degrees retarded. This is my understanding of the tables. Look at the low table in either an 08 or 09 5.3 calibration with VVT and you will see a table that makes sense without all the stupid part throttle retard.

[GHuggins]

I've always seen the cam timing match what's in the table. When at 0 where it was installed that then equals 0 in the cal. Maybe I'm wrong but then all of the cam settings don't make sense off of cam cards?

[Dutch]

You both are correct - I confirmed that the values in the tables appear to represent whole degree offsets from the installed cam position.
At least thats how it is with this ECM and OS.

I reinstalled the cam at 3 degrees advanced, and will retard it from there.

Thanks for the help!

[verlon]

There are three Gen4 camshaft actuators.

2006-2015 12586481 Sprocket 3-bolt
2007-2017 12591689 Sprocket 1-bolt
2007-2008 12585994 Actuator 62* [17* Adv to 45* Ret] (L92)
2007-2014 12606358 Actuator 52* [ 7* Adv to 45* Ret] (Others)
2008-2013 12602699 Actuator 46* [17* Adv to 29* Ret] (Hybrid LFA, LZ1)

L96 utilizes 12606358 Actuator with 52* CKP authority. It parks fully advanced at -7* CKP (or -3.5* CMP).
Gen4 ECM Cam Position tables references camshaft park position so you have to simply add 3.5* to your desired position and put this to calibration.

P.S. 1:8 cam position thing came from some E39 OSes wrong HPT definition.

[GHuggins]

There are three Gen4 camshaft actuators.

2006-2015 12586481 Sprocket 3-bolt
2007-2017 12591689 Sprocket 1-bolt
2007-2008 12585994 Actuator 62* [17? Adv to 45* Ret] (L92)
2007-2014 12606358 Actuator 52* [ 7? Adv to 45* Ret] (Others)
2008-2013 12602699 Actuator 46* [17? Adv to 29* Ret] (Hybrid LFA, LZ1)

L96 utilizes 12606358 Actuator with 52* CKP authority. It parks fully advanced at -7* CKP (or -3.5* CMP).
Gen4 ECM Cam Position tables references camshaft park position so you have to simply add 3.5* to your desired position and put this to calibration.

P.S. 1:8 cam position thing came from some E39 OSes wrong HPT definition.

This helps to explain the offset setting calibration in the gen V's although they state it as 2 degrees instead of 3.5. Always wondered about that. As always, Thank you Verlon

So basically the cam companies are just stating "there" settings from the "0" setting right? OR do you know if they actually mean 7.5 when they say 4? Guess you can't speak for them, but didn't know if you had talked to one of them or not.

I've always checked cam timing with them installed with the actuator in it's locked position, which I thought was 0, but maybe not?

[verlon]

This helps to explain the offset setting calibration in the gen V's although they state it as 2 degrees instead of 3.5. Always wondered about that. As always, Thank you Verlon

Gen5 uses different actuator which can have different parked position. I have no accurate data about it.
Where did you seen offset setting in the calibration?

So basically the cam companies are just stating "there" settings from the "0" setting right? OR do you know if they actually mean 7.5 when they say 4? Guess you can't speak for them, but didn't know if you had talked to one of them or not.

I've always checked cam timing with them installed with the actuator in it's locked position, which I thought was 0, but maybe not?

Usually they use 12591689 sprocket as reference ("0") position. That means parked actuator will be advanced (except Hybrid, which parks fully retarded).

[GHuggins]

I guess this setting is in both the 4td and 5th gens, but would intake min not be the offset at that point? I just figured since it was showing 2 degrees that meant it could move 2 degrees advanced based off of what you stated and then actual 0 would then be 3 degrees which sort of puts things how you said? Is that wrong?

Also if one wanted to run the cam in it's full advanced position at idle, could you then put 2 into the min idle setting and it idle there? Or would you need to then put a (-2) in that setting since it's the one table that will allow negative settings?

intake min.jpg

[GHuggins]

Then I also have another question solely in regards to fixed cams. Should we then be setting the cam tables to 3 instead of 0? I assume once you set the cam to none it's ignored anyway or at least that's how I've always thought of it. Just didn't know if it was like some of the newest stuff where tables are still referenced even though they are set to be ignored.

[2xLS1]

Then I also have another question solely in regards to fixed cams. Should we then be setting the cam tables to 3 instead of 0? I assume once you set the cam to none it's ignored anyway or at least that's how I've always thought of it. Just didn't know if it was like some of the newest stuff where tables are still referenced even though they are set to be ignored.

I don't know how a table could do anything without a phaser present.

[GHuggins]

Yeah, I guess that was meant more for the newer fifth gens. I was wondering in regards to it influencing torque management some weird way. Even with components missing they'll still use tables that should be locked out. O2's are a good example. Remove the rear O2's then have a precat one go bad or even make the mistake of unplugging a precat before the ecm completely 100% powers down. Swap in a new precat. It won't run right and will have completely screwy fueling just for that bank until you reinstall the rear O2's so they can run through their redundancy self check procedures. Really stupid how the engineers set them up. Guess on that one it's not technically a fair example as you can't 100% kill the rear O2's on the E90's short of killing codes for them. Another good example would be a VE tune. Even though you fail the MAF it'll still use airflow calculations from it somehow to control the airmass side of the torque models even if it's unplugged. Reason why I started dialing in the MAF tables even with failed MAF's. Actually proved that one on a couple of SD running trucks. One of which had it completely unplugged. I increased the MAF scaling to more realistic numbers he should be seeing and it increased his line pressure. A lot of things don't make sense, but if code ties to code it still seems to always be at play somehow. Only reason I asked that question, which I know seemed completely stupid

On a side note Verlon. Have you been able to get into the E90's?

[verlon]

I guess this setting is in both the 4td and 5th gens, but would intake min not be the offset at that point? I just figured since it was showing 2 degrees that meant it could move 2 degrees advanced based off of what you stated and then actual 0 would then be 3 degrees which sort of puts things how you said? Is that wrong?

intake min.jpg

This is not offset, this is minimum allowed commanded actuator position. Actuator will be kept parked for any desired position lower than this threshold. It is used to avoid fretting of actuator parking pin.

Also if one wanted to run the cam in it's full advanced position at idle, could you then put 2 into the min idle setting and it idle there? Or would you need to then put a (-2) in that setting since it's the one table that will allow negative settings?

I can tell only for E38/E67/E78/E92. All LS engines (except Hybrids) are stock running with parked (fully advanced) cam at idle and zero position in the tables means fully advanced.

Then I also have another question solely in regards to fixed cams. Should we then be setting the cam tables to 3 instead of 0? I assume once you set the cam to none it's ignored anyway or at least that's how I've always thought of it. Just didn't know if it was like some of the newest stuff where tables are still referenced even though they are set to be ignored.

Those tables are meaningless when cam is set to none. But you have to be very careful if you are using stock VVT calibration with simple sprocket and cam set to none. While actuation is completely disabled, actual cam position is still measured and used in VVE, Virtual Torque and Injection timing.

Yeah, I guess that was meant more for the newer fifth gens. I was wondering in regards to it influencing torque management some weird way. Even with components missing they'll still use tables that should be locked out. O2's are a good example. Remove the rear O2's then have a precat one go bad or even make the mistake of unplugging a precat before the ecm completely 100% powers down. Swap in a new precat. It won't run right and will have completely screwy fueling just for that bank until you reinstall the rear O2's so they can run through their redundancy self check procedures. Really stupid how the engineers set them up. Guess on that one it's not technically a fair example as you can't 100% kill the rear O2's on the E90's short of killing codes for them. Another good example would be a VE tune. Even though you fail the MAF it'll still use airflow calculations from it somehow to control the airmass side of the torque models even if it's unplugged. Reason why I started dialing in the MAF tables even with failed MAF's. Actually proved that one on a couple of SD running trucks. One of which had it completely unplugged. I increased the MAF scaling to more realistic numbers he should be seeing and it increased his line pressure. A lot of things don't make sense, but if code ties to code it still seems to always be at play somehow. Only reason I asked that question, which I know seemed completely stupid

On a side note Verlon. Have you been able to get into the E90's?

Haven't put my hands on E90 and it's not likely I will. We have almost no such cars and trucks.

[GHuggins]

This is not offset, this is minimum allowed commanded actuator position. Actuator will be kept parked for any desired position lower than this threshold. It is used to avoid fretting of actuator parking pin.

Also good to know and helps explain some other things I've observed over the years with the way it seems like a cam will jump at times. If I lower this to 1 will it cause damage?

Those tables are meaningless when cam is set to none. But you have to be very careful if you are using stock VVT calibration with simple sprocket and cam set to none. While actuation is completely disabled, actual cam position is still measured and used in VVE, Virtual Torque and Injection timing.

So, set the tables to 0 and 0 out the variable cam settings for VE. Are there variable cam settings anywhere for the torque model or do you literally have to make the torque model settings all the same as that would really suck... Or since variable is 0ed out and the tables are 0ed out would it then only reference the 0 torque model row regardless?

Haven't put my hands on E90 and it's not likely I will. We have almost no such cars and trucks.

This also really sucks. Seems all of my coders can't or won't be able to get into them. I actually have something else to talk to you about, but will email you in regards to some other tables. As always thank you Verlon...

[verlon]

Also good to know and helps explain some other things I've observed over the years with the way it seems like a cam will jump at times. If I lower this to 1 will it cause damage?

It will not cause instant damage, just wears a little bit faster. But if it will make clicking noise revert back to stock.

So, set the tables to 0 and 0 out the variable cam settings for VE. Are there variable cam settings anywhere for the torque model or do you literally have to make the torque model settings all the same as that would really suck... Or since variable is 0ed out and the tables are 0ed out would it then only reference the 0 torque model row regardless?

1. Zero out variable cam settings for VE
2. Dublicate rows for virtual torque