E250 from hell.. weird CKP sensor signal fluctuation.

Long story short, Ford E250 2008 5.4L, the car shuts Down entirely, sometimes after 10 minutes, sometimes Even after 2 hours, the trouble codes are

*P0600 Serial Communication Link - Manual and Automatic Transmission
*P2105 Throttle Actuator Control System - Forced Engine Shutdown - Manual and Automatic Transmission
*P061B Internal Control Module Torque Calculation Performance - Manual and Automatic Transmission

We have already changed PCM, ignition coils and throttle body and nothing, i decided to scope the CKP and noticed a strange and constant fluctuación so i decided to take a look at the reluctor wheel but it looks alright, what else can be cauaing this strange fluctuation and could that be the source of this problem?

Greetings everybody

I think BEN THOMPSON did a video on utube on jeep liberty a few months ago. Just Lok for it

Is your ckp signal wire touching the CMp signal wire? Unplug computer and ohm check the harness?

mashili wrote:

I think BEN THOMPSON did a video on utube on jeep liberty a few months ago. Just Lok for it

I'll look for it, thanks.. i'm running out of options...

ferris48 wrote:

Is your ckp signal wire touching the CMp signal wire? Unplug computer and ohm check the harness?

Why would you think they could be touching? I think if they we're touching the signal would be way more erratic, i'll look into it still..

mashili wrote:

I think BEN THOMPSON did a video on utube on jeep liberty a few months ago. Just Lok for it

Are you sure thats the name? could not find anyone doing diagnostics with that name...

samuel.barajas wrote:

ferris48 wrote:

Is your ckp signal wire touching the CMp signal wire? Unplug computer and ohm check the harness?

Why would you think they could be touching? I think if they we're touching the signal would be way more erratic, i'll look into it still..

The fluctuation is occuring every 2 rotations of the crankshaft and it dips down and up again like a cmp pulse. Seems like the capture was taken at 1200 rpm thereabouts so i can't explain how the engine could still be running with the signals crossing over like that

Also, The name is Bernie Thompson he has youtube channel Automotive Test Solutions https://www.youtube.com/@AutomotiveTestSolutions

ferris48 wrote:

samuel.barajas wrote:

ferris48 wrote:

Is your ckp signal wire touching the CMp signal wire? Unplug computer and ohm check the harness?

Why would you think they could be touching? I think if they we're touching the signal would be way more erratic, i'll look into it still..

The fluctuation is occurring every 2 rotations of the crankshaft and it dips down and up again like a CMP pulse. Seems like the capture was taken at 1200 rpm thereabouts so i can't explain how the engine could still be running with the signals crossing over like that

Also, The name is Bernie Thompson he has youtube channel Automotive Test Solutions https://www.youtube.com/@AutomotiveTestSolutions

Yeah the every 2 rotations of the crankshaft has me thinking it is something that occurs once every full cicle, but the more obvious culprit would be an ignition coil of which we`ve already changed all of them..

I did got to Bernie Thompson, I'm going through the video it is pretty interesting but the car that he is checking is 2010 jeep patriot with a Hall effect CKP, so i don't think it is going to be a similar kind of situation, the van has an inductive type.

Thank you very much for your replies.

This is the first video that came to mind:



Cliffnotes version: The crank bolt was loose, allowing the reluctor to flop around. I would be surprised if that's the case here, but food for thought anyway.

It does so happen that there's a CMP pulse right around where your crank signal does its weirdness. :huh: This is a known good from the Rotkee library:

Does the deviation of the crank signal disappear when cranking the engine with the coils disconnected?

I would expect an ignition interference with the crank signal to look different than the pretty consistent deviation your captures show....

The photo indicating the zoom position within the whole buffer seems to show another irregularity as a change/decrease in voltage level at the end of the trace.

So against my best guess it is indeed the camshaft signal overposing to my crankshaft signal, don't know how it is possible and why just the first pulse of every cycle, tomorrow ill do more testing, right know i just unplugged it and the interference went away, replugged it and it came back, props to the 2 guys that saw a camshaft signal there :lol: :lol: still cant quite believe it.

Cheers.