2004 Nissan Sentra starting and idling issues

Tiny
CAPTKCP
  • MEMBER
  • 2004 NISSAN SENTRA
  • 1.8L
  • 4 CYL
  • 2WD
  • AUTOMATIC
My car is giving me issues with driving and idling. I ran the trouble code and it throws a camshaft positioning sensor I replaced it and I am still getting the same issues. I have to keep the sensor out a little too even get the car to run. This is the third sensor I have tried I clear the code but it comes back. Any ideas to solve this issue.
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Thursday, July 24th, 2014 AT 7:55 PM

6 Replies

Tiny
CARADIODOC
  • EXPERT
Yup. Diagnostic fault codes never say to replace parts or that they're bad. They only indicate the circuit or system that needs further diagnosis. When a sensor is referenced in a code, that sensor is the cause of it only about half of the time. You also have to look for cut or grounded wires and corroded or stretched connector terminals.

You didn't say what code was set. There are multiple codes that refer to an incorrect voltage on one of the wires, and there's different codes that refer to a missing signal, even though the circuit is okay electrically. That's where incorrect spacing comes in.

By backing the sensor out, it won't generate a signal and the Engine Computer might default to the crankshaft position sensor as a backup and try to run on that.
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Thursday, July 24th, 2014 AT 8:11 PM
Tiny
CAPTKCP
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The code was a p0340 this is what I have done so far. I replaced both the camshaft and crankshaft sensors. And check the wires from the camshaft sensor to the Ecm they are good I'm still having issues getting it to start the code is no longer showing. It sound like it wants to start from time to time but won't keep running the only thing I haven't done is replace the ecm. Before I go that route is it possible to test the ecm out side of the vehicle
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Thursday, July 31st, 2014 AT 2:43 PM
Tiny
CARADIODOC
  • EXPERT
P0340 - Camshaft Position Sensor Circuit Malfunction

Unfortunately that code isn't very descriptive, but it suggests it's not an electrical problem. About all you can do is measure the voltages on that sensor but you have to do that with it plugged in by back-probing through the rubber seals. Typically you can expect to find 5.0 volts on the feed wire, and 0.2 volts on the ground wire. Beyond that you need a scanner to view live data to see if the signal is present.

Very often cam and crank sensor codes don't set just from cranking the engine. They set when the engine is coasting to a stop during stalling. You have to work with the code you read before any service was done or the battery was disconnected to erase the code. That's why it's important to read and record them before anything is done that will erase that memory.

The only way to test the computer is with very expensive specialized equipment that only the rebuilders have. For the rest of us, all we can do is to be sure we have all the 12 volt supplies, all the grounds, and all the proper inputs. If we have those and the computer is good, we'll get the proper outputs, ... Provided nothing is shorted on those circuits. There's often four 12 volt feeds and four ground wires. If you're missing the 5.0 volts to the cam sensor, that circuit feeds a number of other sensors, and any one of them could be shorted. To find that you'd have to unplug them, then turn the ignition switch off and back on to reset the power supply. Once you get the voltage back, monitor it as you plug each sensor back in. You'll set a lot of fault codes but it will identify which one is killing the 5.0 volts.
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Thursday, July 31st, 2014 AT 7:43 PM
Tiny
CAPTKCP
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Ok this what I have done so far. I have replaced both the crank and cam sensors ram the wires for sports and replaced the ecm and I still get the same issue of crank but no start I can here the fuel pump kick on I have even tried spreading starter fluid and still nothing every so often it will sound like it wants to start but won't I'm at my wits end. When I do a search for this issue it seems everyone in the world who owns a nissan has the same problem at about the same miles but Noone has a solution. That is divinitive
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Saturday, August 9th, 2014 AT 8:22 AM
Tiny
CAPTKCP
  • MEMBER
I checked fuel pressure it hits higher then what my Guage can read but quickly disapates. This is reading sight from the fuel line to the Guage I also checked for spark I don't get any spark both with the old and new ECM's I get the old code of the p0340 with the old ecm but not on the new one I also checked compression and it is fine and nissan is of no help
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Saturday, August 9th, 2014 AT 12:12 PM
Tiny
CARADIODOC
  • EXPERT
Don't concern yourself with the fuel system or starting fluid. It's the no-spark you need to address. Very often cam and crank sensor codes will only set when the stalled engine is coasting to a stop. Once it is erased, which also happens when the computer is unplugged to replace it, the code is erased and may not set again just from cranking the engine. You would need a scanner to view live data and see if a signal is listed as missing.
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Saturday, August 9th, 2014 AT 10:07 PM

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