Intermittent stall

Joseph Technician Wood Dale, Illinois Posted   Latest  
Case Study
Driveability
2006 Jeep Grand Cherokee Limited 5.7L (2) 5-spd (545RFE)
No Codes

We had a truck brought into our shop yesterday with an intermittent dying out problem. Scanned vehicle and found no codes. I brought the vehicle in and immediately hooked up my pico. I current ramped all 8 coils, fuel pump,back probed a fuel injector for sync and hooked into the crank sensor at the computer. Vehicle dies out. The crank sensor has 1 long tooth and one long missing tooth for sync. So when the tone ring passes one it should be 5 volts and when it passes the other it should be ground, and they should alternate evenly. I found that when it should be 5 volts it goes ground for three consecutive times in a row causing the vehicle to lose spark and die out. I verified the wiring integrity and replaced the crank sensor.

P.S. If you look at the waveform on pico, the event happens on page two. within the first ten seconds. 

+6
Orlando Technician
Toronto, Ontario
Orlando Default
 

I'm surprised that it wouldn't register the long tooth but still pick up the others. Good job!

+2
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Stuart Mobile Technician
Blue Island, Illinois
Stuart Default
 

Must be a common issue with Jeeps and Dodges with this motor because I had 2 with the same issue recently.

+2
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Angel Technician
Boston, Massachusetts
Angel Default
 

Great diag, Thanks for sharing Joseph

0
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