1998 QX4 Chocking / Backfiring Need Help

[Mick300ZX]

I was driving my QX4 at a highway; regular driving conditions (60mph) and it just started backfiring/chocking to the point that it was shacking like an earthquake. Got to my exit and it just died at a red light. It did start again and was able (after stalling a few times) to make it home.

Hook it up to my lap top and gave me codes P0340 (pending) Camshaft position sensor (CMPS) and P1336 Crankshaft position sensor (CKPS)

Try to start and it would not. Sat there for a day and it did started right up, went around the block with no problems, but I’m afraid to use it before I get the codes solved.

Now is one code triggering the other? What should I do first? Any suggestions will be greatly appreciated.

Thanks in advance.
Modified by Mick300ZX at 3:24 PM 5/22/2008

[nissandoms47]

From what ive learned about the crankshaft position sensor on the Qx4s/pathys is that it is only used for diagnostics, not to actually run the engine but I might be wrong. If both your camshaft position sensor and crankshaft position sensors have gone bad then the ECU has no idea where the engine is in its rotation cycle which probably caused it to die and stall and not start back up. IIRC the camshaft position sensor is built into the distributor and cannot be replaced without replacing the whole distributor. I would just reset the codes and see how it drives. It could just be a hiccup. Ive had it happen once or twice in my pathfinder.

[Mick300ZX]

From what ive learned about the crankshaft position sensor on the Qx4s/pathys is that it is only used for diagnostics, not to actually run the engine but I might be wrong. If both your camshaft position sensor and crankshaft position sensors have gone bad then the ECU has no idea where the engine is in its rotation cycle which probably caused it to die and stall and not start back up. IIRC the camshaft position sensor is built into the distributor and cannot be replaced without replacing the whole distributor. I would just reset the codes and see how it drives. It could just be a hiccup. Ive had it happen once or twice in my pathfinder.

I will try that, this is the second time that it happens in three days.

If it does happens again, can I assume that the camshaft position sensor is going or went bad? Than my next step would be to change the whole distributor?

[nissandoms47]

Thats right. As far as the crankshaft position sensor. Thats a little harder to change out because it is located on top of the bellhousing on the drivers side. Unless you have a small hand its very hard to get to.

[Mick300ZX]

Started the QX4 today, let it warm up and did it again. At this point, I'm just going to change the crankshaft position sensors and the distributor. As soon as I finish, I'll post again with the results.