2007 6.0L LY6 crank and cam signal waveforms (58t crankwheel)

Hopefully, this will help others in their research, and to check if they installed their crank reluctors properly on this engine family.
This is from a 2007 rwd silverado 6.0L LY6 engine with displacement on demand feature (kills cyls 1,4,6,7 on the highway).
This engine has the 58T reluctor and not the 24x reluctor.
Interesting thing I found out....the #1 TDC moment occurs at exactly the same time as the gm 3.9L v6 engine (the one that jumps time alot).
There is a bulletin on the 3.9L slipping its reluctor out of time, probably after an overheat condition.

so....here we go.
I count the first tooth after the 2-tooth gap as 1.
The width of each tooth is 3 degrees. Top or bottom is the same in the pictures. The large gap is 12 deg. wide. (2 missing teeth, including valleys)
When I describe a tooth edge, I will say H2L for logic High going to Low, and L2H for logic Low going to High.

Attachment 13909

In the following waveforms: 1/yellow= cyl #1 compression, 2/green= #1 injector, 3/blue= cam signal, 4/red= crankshaft signal.
#1 TDC occurs @ 14T (H2L) edge.
End Of Injector Time occurs (in double-fire mode) @ center of tooth gap and 43T (H2L) edge.
The computer detected the misfire I created with my setup, and put itself into double-fire mode. Sorry, couldn't be avoided.

Attachment 13910
This is the cam reluctor/gear used in this engine. I just am not sure if a raised portion is logic HIGH or LOW. My guess is HIGH = raised.

Here are the higher resolution shots for all those tooth-counters out there. Events are edge clocked, per typical design.
Attachment 13911 Attachment 13912 Attachment 13913 Attachment 13914 All taken @50ms sweep time.

These are my other shots I took.
Attachment 13915 @200ms
Attachment 13916 @100ms


I may edit this later to provide details on the 4X cam signal, but it is very late, and I am tired. Took forever to get ahead of my workload in order to snag these shots before the customer picked it up. Hopefully this information is useful, since no one has ever posted this data on the web, yet.

Thank you vilefly! That is awesome of you to share your "homework"!

I'm thinking about how to expand on your "homework" to build a Gen IV harness test fixture. It would awesome if a harness could be verified before installation. I'm thinking about a test fixture that would use a "mule" computer with CKP / CMP sensors being triggered by a sync'ed cam / crank trigger wheels. With the CKP / CMP inputs going to the computer, a scan tool connected to the ALDL could be used verify RPM's, coil packs are working, and other sensor inputs. The harness test figure would be able to confirm the computer connectors and sensor connectors are correctly wired.

dave w

Thanks. I figure since I can't be the brains, I can be the brawn.......and snag these truth-telling snapshots.
I spliced the 50ms sweeps together, and worked out a truth table according to the crank signal.

CAM---------CRANK---------EVENTS

H ----------- GAP----------- EOIT
H2L--------- 9T L2H
L2H-------- 13T L2H
H ----------14T H2L ------ #1 TDC-POWER STROKE
H2L-------- 39T L2H
L ------------GAP----------- EOIT
L2H ---------3T L2H
H2L--------- 9T L2H
L ----------14T H2L ---------#1 TDC-EXH/INT STROKE
L2H --------33T L2H
H2L ------- 39T L2H
L2H ------- 43T L2H
H ------------GAP ----------- EOIT

The EOIT occurs at 3* after H2L, where an imaginary L2H pulse edge would be if no teeth were missing. (IN DOUBLE-FIRE MODE)

I must also ask that someone post these pictures in a more public way, besides this forum. I have no public accounts that are google searchable......I think.....perhaps....I dunno. Spread the information around, please.
Should I ask that we make this thread "sticky" ?
Oh, btw.....the spliced nasa-like picture.
Attachment 13927

Another great chart from vilefly.
Thanks for the effort.

I draw this chart but later noticed that #1 tdc is offsetted by 12 degrees, according to pressure data. Really interesting why cam wheel events don`t match TDC but are offsetted, is the chain stretched, wheel misaligned or gm design it that way. The way it is designed might suppose some variable timings in mind. Offsetting +-12 degrees or total of 24 degree cam movement.

There is another strange thing in the graph. Right after the empty 58x slot there is one wider slot. I looked at all kind of pictures of the wheel and couldn`t find one that match that pattern. Is the misfire huge enough to slow down the graph or something else I am missing.
The empty slot must be 15 degrees wide. 3 empty slot + 2 full slots missing.

The first pulse from the 58x signal is stretched from the misfire, for sure.
This engine also had 200,000 mi on it, so there might be a little timing chain stretch in there, but i could not wiggle the chain by hand easily. I didn't get a chance to nab a shot without the pressure sensor connected, as I was supposed to be replacing the oil pan at the time.
This is why I posted the data as referenced in relation to the 58x signal. Wish I had more time with the vehicle. My original source vehicle had 58k miles on it, but I was being rushed badly to get it out on time, despite the 5 hr labor time for the oil pan, as it was 4wd. Lucky for me, the 200k vehicle came in just as the other left.
I suspect maybe a maximum cam error of 4 degrees (+/- 2 degrees). Since the teeth are 3* wide, this seems about right.

I suspect the 12* offset might be a base timing thing. Probably really 10*, since this is common practice on many engines, but the engine doesn't care that much.


The cam reluctor in your picture Kur40, turns clockwise, with the crankshaft. Please make your corrections as needed.

You are right about the rotation. I will try to fix it an reupload the chart.

I think the cam wheel is offsetted for one reason. Fast crank syncronization.

Missing crank teeth slot + high cam signal = 90* before #1 tdc
Missing crank teeth slot + low cam signal = 90* before #6 tdc

My estimate is that the first tooth after the missing ones` is 90 before #1tdc. So the crank wheel is retarded 90 degrees also.

Another mystery to solve is why the wider tooth slot appears each 360 degree of crank rotation. The misfire should occur each 720 degree of crank rotation.
I will keep thinking about it.

After counting teeth, I concur with the 90* strategy. I still wonder about the "fat tooth" thing. I think it might be a reluctance-charging thing, but these are magnetorestrictive sensors, and I need to read up on inductive charging/etc theory with these things. Maybe they are regular hall effect sensors, but I think they would not show a fat tooth for any reason, though. Another waveform capture may be needed to answer this.

Ok. After scouring the web, I found another 58x waveform from a Picoscope. It had no fat tooth. So, I looked at my 3.9L saturn crankshaft sensor capture, and found the fat tooth again. So I have come to the conclusion that my test leads suck. Personally, I blame Snap-on tools. They don't use shielded BNC cables like everyone else for selfish proprietary reasons, even though it is a proven industry standard. I have always hated those test leads.....they are simple banana plugs that stack on each other for grounding. Ultra-stupid design. Stray capacitance is a problem with them. I should sue them for "deformation of waveform" .......the scurvy naves should take a long walk on a short plank.

Incidentally, the best scope tuned for automotive is the Picoscope.