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Re:Re:2013 Gm 2.4 ecotec cam/crank waveform

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1 year 3 weeks ago #60994 by Ben
Can't get into pico waveform library at the moment anybody have any insight on this 1? It's been to several other shops that did timing work to it (haven't received copy of invoice to know what yet) notice everything is the same size in these waveforms except the width of and between the 2 big towers 1 is with the exhaust actuator unplugged

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1 year 3 weeks ago #60997 by juergen.scholl
Not sure about channel 1 (blue) in your screen screen shot being a crank signal...could be a sync?

Maybe you find what you're looking for in the rotkee library:

rotkee.com/en/waveform-library?brand=161&model=2488

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1 year 3 weeks ago #61015 by Ben
Sorry I was having all sorts of technical issues yesterday, I got into the crank sensor for giggles today here's a better picture of what's going on, I can send a pico file to anyone that wants it

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1 year 3 weeks ago #61016 by Ben
Here's a shot of a known good from pico library, the gap on intake and exhaust is 22deg

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1 year 3 weeks ago #61017 by Ben
My symptom is engine noise/preignition but here's where it gets weird 1st cold start it runs fine and exhaust sensor pattern matches intake (phasing is active on these at idle) 2nd if I disconnect the exhaust phaser the pattern width returns to normal and engine runs smoothly without any noise....

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1 year 5 days ago #61304 by Ben
Anyone have any insight on the varrying widths of the cam sprocket? my theory is a bad phaser(leaking oil pressure)

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1 year 4 days ago #61308 by Matt T

Anyone have any insight on the varrying widths of the cam sprocket? my theory is a bad phaser(leaking oil pressure)

Maybe the oil pressure is moving something changing the CMP air gap? Bad phazer, phazer loose on the camshaft or possibly camshaft endfloat.

Why do Pico always put the cursor box in the way? I don't think low oil pressure would cause this but an air gap problem could.

The following user(s) said Thank You: Ben

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1 year 4 days ago #61310 by Chad
Here is a Known Good from a 2016 2.4 Ecotec, with solenoids disconnected.

Pico File:

File Attachment:

File Name: 2016 2.4 E...d.psdata
File Size:2,299 KB

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1 year 4 days ago #61315 by juergen.scholl
Could you share the PSD file? What seems to be an extra pulse is a repetitive occurrence at specific rpm? Could it be cam slap?

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1 year 4 days ago #61320 by Ben
Yes I can email the files to anyone who wants a copy, I don't believe there is an extra pulse just that the widths of the phaser teeth change when its warmed up and phaser is active. If I disconnect the solenoid it corrects itself immediately. I hadn't given thought to the camshaft potentially shifting from oil pressure I was leaning more towards oil being thinner when engine is warm and the phaser leaking oil

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1 year 4 days ago #61324 by juergen.scholl
Pm sent.

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1 year 4 days ago #61325 by Ben
Email sent, I am not familiar with the programs you mentioned in your pm.

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1 year 4 days ago #61326 by Ben
hmmm I didnt see the attached picture on the tapatalk app , Im not sure what that little pulse is , I did not notice that before I was just concerned with the length of the on time /offtime changing

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1 year 4 days ago #61327 by juergen.scholl


Why do Pico always put the cursor box in the way?


It's the user, not the software :angry: :P

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1 year 3 days ago #61334 by Ben
That extra sensor pulse happens to be at the same time as a secondary ignition strike, the voltage spike doesn't seem excessive but maybe this sensor is right on the edge of failing ? Although that doesn't make sense that it acts right if exhaust solenoid is disconnected?

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1 year 3 days ago #61335 by Ben
Ok here's where I'm at, I rechecked base timing compared to matt's disconnected solenoids and I match within 1 degree on both cams. If I let it run long enough it sets DTC p0366 and disables the exhaust cam solenoid and runs considerably better. I will try to attach a fresh capture to this post.

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1 year 3 days ago #61338 by Matt T

That extra sensor pulse happens to be at the same time as a secondary ignition strike, the voltage spike doesn't seem excessive but maybe this sensor is right on the edge of failing ? Although that doesn't make sense that it acts right if exhaust solenoid is disconnected?

The ignition spike may occur when the CMP signal is high with the phaser unplugged??

There appears to be two problems with the CMP waveform but which one is THE problem making the vehicle run like crap and set P0366? I'd probably try some CMP and/or coil swaptronics first.

And re. the vehicle running ok when cold, is phasing active? A lot of stuff like that doesn't turn on until the engine reaches a certain temperature.

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1 year 3 days ago #61340 by Ben
Yes phasing is active on cold start, appears to be about 5 degrees of phasing at idle(according to scan tool). I'm leaning towards swapping the intake and exhaust sensor and seeing if we change anything. (Although I took some more captures today and did not find any senor dropouts) (not that that says much I didn't see the first 1 right in front of me!) I was to focused on the varying widths of the sensor signal

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1 year 3 days ago #61343 by Ben
Swapped intake and exhaust sensor and it helped! It's not perfect but it's better. Bad news though there's was a bunch of metal on the sensor soo the timing chain must have eaten the guide...

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11 months 3 weeks ago #61477 by Ben
Ok since the last update I replaced sensor the suspect sensor with (now located at the intake cam) and it ran just like before swapping sensors, I removed both sensors and the exhaust sensor was covered in metal sludge again so I removed valve cover cleaned the cam target and general sensor area and it runs signicantly better. However I do still notice at warm idle it does too much phasing almost starts to run rough then snaps back to smooth idle (I assume timing solenoid is turned off briefly at that time)

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