Crankshaft position sensor question

[heavenjumper]

Iknow this will be kinda long, but any help is greatly appreciated. I recently bought a 93 Pathfinder and was told a bunch of parts had been replaced, but it turns out that most of them weren't replaced, were replaced incorrectly, or were replaced with used parts. We've already repaired a couple of things that were necessary, but in the last 2 days we've had a new issue pop up. It was running fine and my husband drove into town and as he was driving the vehicle just cut off. It did the same thing 3 times, but cranked right back up each time. The next day, it died randomly while he was driving again but still cracked back up. After parking it at one point, it didn't want to crank at all. It has a brand new alternator and battery, but somebody jumped it off and it stayed running for about 2 minutes, then bogged down and died and wouldn't crank again. I got off work and somebody else offered a jump because it acted like the battery was dead. It took several attempts to get it cranked that time with it going between trying to start and not trying at all. We ended up having it towed home because on the 2 occasions we did get it cranked, it would run for about a minute and then bog down and die. After sitting for a day, we used a jump box and it cranks up fine, but still bogs down and dies after several minutes running. I'm thinking it's the crankshaft position sensor, but I can't find the sensor to save my life! The part online also shows to be a disc shape, but in any videos that I watch it looks more like a tubular shape... which one is correct? I need to get this vehicle operational ASAP, so any help is greatly appreciated! 

[peejay]

Could you mean the camshaft position sensor (located in/part of the distributor) as I don't think these models have a crankshaft position sensor.

 

Also, a fuel pressure check may be another good thing to verify/rule out.

Edited May 24 by peejay

[Slartibartfast]

These only have a camshaft position sensor. It's inside the distributor. It's an optical sensor, like what's in an old computer mouse with the ball in it, not a hall-effect like most other stuff. There's a plate under the rotor in the distributor, and the sensor is under that. I've heard of them acting normal when cold but playing up when warm, which sounds like what yours is doing. Check the bearings while you're in there, especially if you find debris under the plate. I don't know whether the worn bearings take out the sensor, or just confuse it.

 

That said, if the starter is struggling/engine is turning slowly/it won't start without a jump, that's not the cam sensor. I would check that the battery is good, and that the alternator is charging it when the engine is running.

 

I recommend downloading the service manual. Free from either cardiagn.com ('90 manual, if yours is square-dash) or Nicoclub ('94/95 manual, round dash). EF&EC is your friend for engine control questions.

 

Sorry to hear it got "rebuilt" with worn-out junk. One of my dad's friends bought a Triumph like that. I think it was assembled with the parts left over from rebuilding a few others. It ran surprisingly well, other than the alarming clacking noise, the clutch that didn't disengage all the way, and the steering column that was about to fall out. It took us a while to sort it out, but it was a nice driver when it left. Hopefully yours comes around too.

[level9]

It sounds like strange electrical issues -> check all of your grounds.

Given the age of the car, I would pull off all of the grounds and sand off the oxidation while checking that the ground is even still there. Do the same to the battery connecting terminals. You can find the locations in the FSM. Also check that the fusible link at the positive battery post is still intact (no signs of burning) and just generally look around for any frayed wires / short-to-ground situations.

[heavenjumper]

On 5/23/2024 at 10:09 PM, peejay said:

Could you mean the camshaft position sensor (located in/part of the distributor) as I don't think these models have a crankshaft position sensor.

 

Also, a fuel pressure check may be another good thing to verify/rule out.

After finally getting the Haynes manual yesterday, I think what the guy I was talking to was referring to on this vehicle is the crank angle sensor. What I can find on parts websites, it looks like a disc with a box on one side. One or more of the fuel injectors being bad is another fear I have that may be the issue. 

[level9]

According to the FSM (EF & EC), if the crank angle sensor is bad, the engine will still start and run in fail-safe mode. It will also trip the 'Check Engine' light (if you have one).

I would try pulling codes from the ECU but honestly if the car requires a jump to start, you aren't getting charged by the alt. And if it's acting like the battery is dead... you have an electrical issue...

[peejay]

On 5/25/2024 at 10:19 PM, heavenjumper said:

After finally getting the Haynes manual yesterday, I think what the guy I was talking to was referring to on this vehicle is the crank angle sensor. What I can find on parts websites, it looks like a disc with a box on one side. One or more of the fuel injectors being bad is another fear I have that may be the issue. 

Now, don't "quote" me on this, but I thought the crank angle/position sensor didn't appear on the Pathfinder until the VG33 engine ('96 and later) as part of OBD-II emissions?

 

Have you downloaded the FSM? The Haynes is good for better explanations of things once you know the problem, but the FSM is more detailed at helping track down the problem first.

[heavenjumper]

4 hours ago, peejay said:

Now, don't "quote" me on this, but I thought the crank angle/position sensor didn't appear on the Pathfinder until the VG33 engine ('96 and later) as part of OBD-II emissions?

 

Have you downloaded the FSM? The Haynes is good for better explanations of things once you know the problem, but the FSM is more detailed at helping track down the problem first.

My husband reminded me that the guy left the old distributor in the truck when we bought it, so I took it apart to find the sensor and it was there, under the plate below the rotor. I've ordered a new distributor so I don't risk damaged any parts to replace the sensor. I'm downloading the FSM now to have it handy as well. 

[peejay]

22 minutes ago, heavenjumper said:

My husband reminded me that the guy left the old distributor in the truck when we bought it, so I took it apart to find the sensor and it was there, under the plate below the rotor. I've ordered a new distributor so I don't risk damaged any parts to replace the sensor. I'm downloading the FSM now to have it handy as well. 

Excellent! (The FSM says to "replace the entire distributor assembly with camshaft position sensor if faulty", so you're on the right track!)

 

Good luck, and keep us posted!

Edited May 27 by peejay
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