Cam Phaser Operation and Monitoring Other Stuff.

[budwich]

I was wondering if anyone has done any active monitoring of the cam phaser operation while monitoring other things in the system such as fuel trims, O2 sensors, etc. Interested in understanding any impacts changes in the exhaust output might have on the downstream results. Of course, I don't really know / understand how the dynamics of the cam changes happen in the first place which needs more reading but just curious at this point.

 

[Mooseman]

I just posted a bunch of YT videos on this engine and the one where he dyno runs it, he shows the difference that the VVT does for power. Quite interesting.

(Videos) 4.2L performance build with dyno

I have watched Richard Holdener do a lot of builds and testing on LS engines and he just happened to do some work on a junkyard 4.2L. It's gonna be a series of videos starting with this intro, calling it the Ameri-Barra 4.2 in reference to the Aussie Barra inline 6.

gmtnation.com

 

[TJBaker57]

I was wondering if anyone has done any active monitoring of the cam phaser operation while monitoring other things in the system such as fuel trims, O2 sensors, etc. Interested in understanding any impacts changes in the exhaust output might have on the downstream results. Of course, I don't really know / understand how the dynamics of the cam changes happen in the first place which needs more reading but just curious at this point.

That old curiosity gets me every time!!

I ised to have a wealth of data available until the phone it was on decided to reset to factory while in my pocket 2nd time it has done this. Anyway, I'll grab some more data for us to examine.

 

[TJBaker57]

Can someone confirm there were changes in the amount of cam angle change available between years? I know there were several iterations of the phaser.

 

[budwich]

sorry I didn't mean to make any other "cats work and get killed"... I am wondering about problems that people are seeing with not working correctly VVT solenoids and the results one might see with "stuck" or otherwise at various times. I have downloaded your PIDs file for this on torque (thanks) and hope to start actively monitoring some of these at times especially around towing heavy.

 

[Mooseman]

It will usually throw a P0014 or P0017 for a bad CPAS. Also seen P1345 but that one is more due to the phaser itself being bad. The system is pretty robust for checks and balances on the VVT if anything is out of whack.

 

[TJBaker57]

I may have mentioned this a few times elsewhere on this site.... the Car Scanner Pro app excels at data acquisition and presentation for later analysis. Below is a short clip showing engagement of my phaser. The chart provides a double Y axis, degrees on the left for desired and actual angles and percent on the right for the solenoid.

edit: I should have added that this graphing is right within the app itself.

 

[budwich]

Good stuff. Of course, The timings are rather interesting which looks like about 40 sec (if I understand the scale correctly). Then a "switch" and then back to the same value. I guess my question would be why the "drop and punch back"? Probably your discussion else where. Thanks for this.

 

[budwich]

Can someone confirm there were changes in the amount of cam angle change available between years? I know there were several iterations of the phaser.

Not sure if this is what you are referring to / asking about, but the SI for 2006 indicates max 25 degree (10%steps to 100 percent). I haven't checked others.

edit: 2008 si indicates the same maximum.

 

[TJBaker57]

Not sure if this is what you are referring to / asking about, but the SI for 2006 indicates max 25 degree (10%steps to 100 percent). I haven't checked others.

edit: 2008 si indicates the same maximum.

Maybe it is another of those 2002 unicorn things... but my phaser never goes greater than about 12°, actual or desired.

Thr particular phaser is listed as fitting 2002 to 2004 only.

 

[TJBaker57]

Good stuff. Of course, The timings are rather interesting which looks like about 40 sec (if I understand the scale correctly). Then a "switch" and then back to the same value. I guess my question would be why the "drop and punch back"? Probably your discussion else where. Thanks for this.

I could look at the rest of the data, like map, etc.. Would maybe find something there. These parameters were selected from a larger dataset and sort of chosen to see the action of the solenoid and reaction of the actual angle. Sometimes the solenoid punches to 100%, I thought maybe to get a fast reaction from the phaser. Other times I don't see the 100%. This could be due to the rather slow refresh rate of using an OBD2 smartphone app and service 22 vs the faster streaming data of service 2C/2A like a Tech 2 does. It's possible the 100% is so brief it is missed by the App. The more pids you monitor the slower the refresh rate as they have to be requested sequentially.

 

[budwich]

I was reading a bit more. The cam phaser is / can be adjusted in 10% increments which gives you 2.5 degrees / increment. Further, the coding (fault) has some timing of 12.5 / 15 seconds to determine whether things are set as expected... ie. if there is a difference (3.5 degrees), that has to exist for longer than the time period before coding. So for some, perhaps a component might be slow to cause change but eventually happens.... will that make any difference overall. Kind of like the o2 sensors (and others) impacting fuel trims but the fault for the trims has to exceed 25% "correction" before being flagged. By that time, it is almost too late if you aren't already looking at / for running issues. I am thinking the same might exist for the phaser operation and resulting motor response overall. Of course, I don't have any idea if this actually means anything. Again, just curious.... especially with the age of my truck and the fact that I changed the VVT with a unit from RA that was "clearance". :-( what the heck is that... old stock that never worked properly or otherwise ...

 

[TJBaker57]

Just watched this video linked below in which Calvin talks a good bit about VVT application, albeit in a far from stock project. At any rate he also states 25 degrees of exhaust cam angle retardation on a 2002. So I am going to go back again and recheck my equation(s) and do some recording with the Tech 2 to see if I screwed the pooch with my existing equation and maybe I am only seeing half of what I should be seeing.

Besides, I think this a cool video and really enjoy watching Calvin's stuff..

 

[mrrsm]

FWIW... You've probably read this Article published about Mr. Ron Kociba (arguably "The Father of the GM Atlas Vortec In-Line Engine Series") about a Dozen Times already. But if not... there is an arcane passage here about his use of "Math Tools" during its development phase that might pique your interest... especially if you can *winkle* out exactly what these are and perhaps even get your hands on one or more of them that could be foundational digital tools to amplify your work on this matter:

http://www.tbmsport.com/images/4200_Overview_1_.pdf

 

[TJBaker57]

I am going to go back again and recheck my equation(s) and do some recording with the Tech 2 to see if I screwed the pooch with my existing equation

Nope! Equations are spot on, or as near as I can figure since the Tech 2 uses only whole numbers here. Round mine and they agree.

 

[budwich]

I seen somewhere (can't remember where and didn't save the link) but it indicated that "normal" phaser operation is 50% so it is likely that you are indeed seeing a correct number. Further, the graph looked exactly the same with two activations close together.... but I do believe it was also a graph that had phasers for both intake and exhaust so that graph might have some differences elsewhere.

 

[TJBaker57]

The odd thing is each time I come across talk of cam phaser operation on the 4.2 they state 25 degrees as a maximum. The numbers from the Tech 2 (and my PID) NEVER go beyond 13 degrees on mine. Is it a case of cam angle vs crank angle I am getting mixed up here??