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Engine Some scope readings for you.

  • Thread starter Thread starter CassieL
  • Start date Start date Jun 2, 2024

CassieL

Active Member
May 15, 2024
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Tyler Texas
Jun 2, 2024
#1
  • Jun 2, 2024
  • #1
These are scope readings I captured when my truck was cutting out and stalling.
I knew this felt like a tfi module so i scoped the pip output and the coil trigger output.
The green line is the pip, yellow line is coil trigger. You can see the trigger signal cutting out while the pip is steady.
The second picture you can see the pip dropping some pulses as the engine is stalling.
After a few more minutes the trigger stopped completely while the pip was normal.
The tfi module (remote mount) was only five months old and standard brand from O'Reilly's.
 

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General karthief

wonder how much it would cost to ship you a pair
5 Year Member
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polk county florida
Jun 3, 2024
#2
  • Jun 3, 2024
  • #2
That's great info IF you know what your looking at, square wave and spikes and sht involves math and science stuff, I slept through that class.
 
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limp

wrap a little cheese around it and its a done
5 Year Member
Oct 4, 2020
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#3
  • Jun 3, 2024
  • #3
General karthief said:
That's great info IF you know what your looking at, square wave and spikes and sht involves math and science stuff, I slept through that class.
Click to expand...
Too many bong hits for me to remember.....
 
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CassieL

Active Member
May 15, 2024
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Jun 3, 2024
#4
  • Jun 3, 2024
  • #4
PIP signal is a square wave. Coil trigger is the coil charging a the firing line. Those aren't spikes it's the firing line.
 
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CassieL

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May 15, 2024
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Jun 3, 2024
#5
  • Jun 3, 2024
  • #5
This one is a longer sample but it's a normal reading of a good running ignition.
 

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BigRix

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Oct 19, 2024
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Tucson
Oct 24, 2024
#6
  • Oct 24, 2024
  • #6
I'm not sure if a link is ok but Scott Brown did a fantastic video showing the problem with modern replacement TFI modules. He uses scope patterns to show that the new ones are not working the same as the originals. Even the new replacements from Motorcraft.

View: https://www.youtube.com/watch?v=-Fsid4EqXak
 
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CassieL

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May 15, 2024
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Tyler Texas
Oct 24, 2024
#7
  • Oct 24, 2024
  • #7
A good pip should be 0-10 volt square wave with one wave being more narrow every 8 pulses. The narrow one is number one cylinder.
 
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Rcdgl

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#8
  • Dec 15, 2024
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What setup did you use to scope this/
 

CassieL

Active Member
May 15, 2024
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Tyler Texas
Dec 15, 2024
#9
  • Dec 15, 2024
  • #9
I use a snap on modis. It's a scan tool and has a four channel scope.
 
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