SureTrack Community Fix: The Pathfinder to the Fix

Real Fixes from ShopKey’s SureTrack® expert information resource are documented issues from actual shop repair records and community discussions. Read on to see how SureTrack can help you correct issues that are not easily diagnosed using OEM information alone. SureTrack is currently available free with the purchase of a current Snap-on® diagnostic software version or in our ShopKey Pro product.


One thing technicians don’t like is when customers worked on their cars themselves, especially after previously bringing the vehicle in for a diagnosis and rejecting service. SureTrack community member Mart2018 had a Nissan Pathfinder in the shop that had been in before to diagnose a misfire but the customer declined the work and took it home and replaced some parts and now it won’t start. They posed their question to the community, and with the help of fellow community member ericsautomotive and others, they were able to resolve the issue quickly.

The following Community Fix summarizes the interaction between members of the community that led to the solution.

Vehicle
2008 Nissan Pathfinder SE 4.0L

Title
Crank, no start, replaced timing chain.

Complaint
Customer complains that vehicle won’t start.

Diagnostic Steps Performed/Parts Replaced
Vehicle was driven in on previous visit for a faulty coil and misfire code. The customer declined work and replaced 2 ignition coils and 6 spark plugs themselves. Pulled plugs and they are wet with gasoline. Put a spark tester on coil and noticed no secondary spark. Tested powers and grounds as well as used a bulb to simulate load and all functions ok. Scanned for DTC and noticed no codes current or pending but monitors had been reset at some point before towed in. Scan tool shows start PID and injector percentage to be within nominal values showing vehicle is aware of request to start. Examined CKP for powers and grounds as well as CMP sensor on drivers bank, easiest to get to, and all tests came back good. Used a lab scope to view patterns and while it wasn’t a good looking pattern there was a presence of a cam and crank signal on cranking. Cycled fuel pump on and off to listen for running as well just to check all aspects of the motor spark fuel and compression. Tested cylinder 2 and cranking was close to 100psi even though a visual inspection with a scope shows fuel wash on the cylinder walls.

Before I Pull the ECM and do resistance testing from sensors and coils to ECM and check for presence of inputs and outputs is there anything that could be a dead giveaway that I’m not seeing?

Best Answer from Community Member ericsautomotive
Try unplugging the cam and crank sensors one by one while attempting to start engine each time. If it fires up? The PCM thinks the engine is out of time !!!

Cause
I unplugged the same CMP sensor (drivers side) and the vehicle DID start and run. While running you can hear a very loud audible of a timing chain that is missing a guide. Vehicle had skipped timing due to an internal timing chain (and or guide) failure. Big thanks to ericsautomotive for the insight and knowledge that hopefully will help others in the future.

Correction
Replaced timing chain and guides. Vehicle now runs as it should.


SureTrack® adds to the power of ShopKey Pro with an exclusive combination of expert knowledge and detailed parts replacement records, all wrapped in an interactive community. Designed to help automotive shops increase accuracy and efficiency from diagnosis to completed repair, the industry’s most comprehensive repair information resource is just a few clicks away.

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About the Author

Nick Taylor

Nick Taylor is the SureTrack Community Administrator and a Senior Applications Specialist at Mitchell 1 with over 25 years of experience with electronic repair data systems. Nick previously worked in the automotive dismantling and engine rebuilding industries.