VVT Tables

[waynehartwig]

How do they work?

The way I understand it, you have three tables of which you can set the Baro amount to switch between them - I'm assuming that if it's below 75 it will use the low table? And then between 75-84 it uses mid and above 94 it uses high? The value in the table retards? cam timing the #* in the table?

I ask because some of the searching I've done has brought up that the phasing runs from about 5* advanced to 50* retard? (I dont recall exact numbers, but it is both ways?)

So that leads me to ask if I set the table at 0*, would that actually be 0*? Or would it be 5* advanced? So like right now, stock, it has 8* in the table up high in RPM's. Woudl that then be 3* retarded? Or 8* retarded?

[waynehartwig]

Searching around I found this thread:
http://www.hptuners.com/forum/showthread.php?t=17883
But I think it confused me more/didn't answer my questions?

But it did get me to look at AllData to try to come up with an answer...

A CMP actuator dynamically changes valve timing events relative to piston timing by controlling camshaft position. This is sometimes referred to as variable valve timing or camshaft phasing. Variable valve timing or camshaft phasing does not change duration or lift.



By advancing camshaft timing, an improvement in low end torque can be achieved.
By retarding camshaft timing slightly, an improvement in high end power can be achieved.
By retarding camshaft timing significantly, an improvement in light load fuel economy can be achieved.
There are 5 cavities divided by vanes within the CMP actuator.



When oil is directed to the advance cavities (1), the camshaft timing is advanced.
When oil is directed to the retard cavities (2), the camshaft timing is retarded.
When oil is directed to both cavities, the camshaft is held stationary.






The 6.0L L76 and 6.2L L92 CMP actuator has a 62 degree range of authority. With the engine not running and no engine oil pressure to the CMP actuator, the high tension spring positions camshaft timing at the 17 degree advanced park position. During normal engine operation and based on performance requirements, the ECM may adjust camshaft timing, as required, within a range from 17 degrees advanced to 45 degrees retard.







The 6.0L LY6 CMP actuator has a 52 degree range of authority. With the engine not running and no engine oil pressure to the CMP actuator, the high tension spring positions camshaft timing at the 7 degree advanced park position. During normal engine operation, and based on performance requirements, the ECM may adjust camshaft timing, as required, within a range from 7 degrees advanced to 45 degrees retard.

So in the table, if you put 0 in the table, is that actually 0*? Or is it the park position? In other words, if you set it at 52 on the LY6 motor, would that actually be 45* retard? And if you set it at 0, would that be the 7* advanced?

[LEDbetter]

Yeah the low, med, and high tables that you mentioned work just as you thought. I got to drive into some higher altitude awhile back and scanned the BARO pressure and seeing where the cam position was. The lower pressure had put it in the med table.

Later on for giggles I maxed out the threshold tables for low, med, and high so that it would be in the low table. I did just that and kept the cam from retarding at cruise. It's all back to normal settings now and I haven't done anymore with it.

[waynehartwig]

Yeah the low, med, and high tables that you mentioned work just as you thought. I got to drive into some higher altitude awhile back and scanned the BARO pressure and seeing where the cam position was. The lower pressure had put it in the med table.

Later on for giggles I maxed out the threshold tables for low, med, and high so that it would be in the low table. I did just that and kept the cam from retarding at cruise. It's all back to normal settings now and I haven't done anymore with it.

[4evervette]

just to throw another Q : how does these table work the the variable cam spark ..the spark tables ?

[cam]

I set the phase curve the same in all three tables and zero's out the VVT spark and started messing with the main spark advance with decent results. Then the weather turned sour so I'll be waiting to spring to start testing results and finish it off on the dyno it but right now my phaser table now looks like this;

[LEDbetter]

just to throw another Q : how does these table work the the variable cam spark ..the spark tables ?

I just made a log with the VVT set to low baro and the variable cam spark looks to be about a tenth of what it is in the cruise areas. WOT, in the high rpms, there were no changes to the variable cam spark. So it looks like there are some multipliers or another that we don't see in the spark menu.

[Higgs Boson]

I zero'd the vcam spark table and just redid my main spark tables. My vvt table looks similar to the one posted above but not quite so retarded.

[cam]

I zero'd the vcam spark table and just redid my main spark tables. My vvt table looks similar to the one posted above but not quite so retarded.

My cam has 4 degrees of advance ground in and I run the comp phase limiter. That table will likely change once I get it on the dyno and see how it responds. I'll post up results but it'll be spring time now

[Closer_2001]

Results? My buddy and I tuned his 2010 Sierra 5.3 this past weekend and I could only get 18* timing advance without KR in the main tables. The VCP was zeroed out. Anything past 18 caused audible knock on 87 and (with a half a tank of 93 on top) or 89 equiv, .5 KR after the 3rd WOT run in 3rd.

[cam]

We're still working on it. The a/f etc is done and dialed now. Hoping to dyno soon and thats where we plan on testing cam timing adjustments to see where we gain/lose.

As of now im only running 8 degrees of retard but it seems to run well