2001 Pathfinder difficult start, pinging when running

[skipfletcher]

Driving home a couple weeks ago my Pathfinder's engine temp shot up so I pulled over and turned it off. Turned the key back on and checked codes through my bluetooth OBD reader. The engine temp was suddenly fine, but I had P0335 (Crankshaft position sensor) and a couple more related to the immobilizer.

Got towed home and started to trouble shoot.

Replaced:
- Crankshaft position sensor
- Starter
- Battery
- Negative battery cable
- checked coolant level
- checked and added oil

Still doesn't turn over when I turn the key. I get rapid clicks when the OBD is installed, and a single click when it is not.

BUT when I connect jumper cables directly from the negative battery post to the starter housing, it DOES START and run about once out of every 5 tries.

While running, there is a constant pining sound coming from the front of the engine. No codes.

My plan is to run auxiliary ground cables around the engine.

This is the weirdest thing. Any suggestions?

[MisterH]

Your immobilizer circuit apparently no longer recognizes your key. You mentioned that you got codes for that fault so you should probably investigate that.,

[skipfletcher]

Follow-up: I got the car to start reliably by adding a 2 gauge wire directly from the battery to the starter. Immobilizer was fine. The codes were a symptom of bad grounding.

The pining noise was from the new CPS being too close to the crankshaft ring. Reinstalled old sensor and problem solved.