Intermittent stall

Joseph Technician Illinois Posted   Latest  
Case Study
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. 

Orlando Technician

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

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Stuart Mobile Technician

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

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Angel Technician

Great diag, Thanks for sharing Joseph

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