0302 Help

[jbea0064]

i have an 06 Pathfinder LE that was running fine earlier. got to a location and when i went to drive home it was a tough start, rough idle and lack of power. got an 0302 code so i changed out the plugs and swapped the # 2 coil for # 4. once started still ran rough as decsribed. read code again after clearing and code still ran 0302, didn't follow coil. is the #2 coil on drivers side as i have read? anybody else have this issue? can anyone point me in the right direction without just throwing parts at it? thank you for any help.

[smj999smj]

Cylinder #2 is the first cylinder on the left, or driver's side (US). I would check the fuel injector circuit using a noid light and doing a resistance check of the fuel injector. I would also check the coil circuit. I would recommend you download a factory service manual for your vehicle, specifically the "EC" chapter, for trouble diagnostic steps for DTC P0302.

[jbea0064]

you don't have a link to the manual do you? i am having trouble finding online.

[eieio]

you don't have a link to the manual do you? i am having trouble finding online.

our very own service manual.........
http://www.thenissanpath.com/filelib/R5 ... ce/fwd.pdf

[jbea0064]

thank you

[jbea0064]

ok. i checked ohm on injector, i checked spark and ground. positive is showing 2.4 volts while running. ground is good. ohm on injector was at 13.6. starting to think it is fuel injector itself, but not wanting to spend $130 to check. it makes me nervous the ohms are close to correct. listened to all 3 injectors on this side, all 3 sound different. #2 here is the quitest.

[smj999smj]

That's why it's good to use a noid light. It plugs into an injector's harness connector and when you start the engine, it will (or should) flash, letting you know that not only is the injector getting power, but that the ECM is pulsing the ground wire to "fire" the fuel injector. If the the noid light is flashing, if you have spark to the plug, and compression is good at that cylinder, then the most likely problem is a bad fuel injector.

[jbea0064]

went and rented oe. about to see. thank you for the help so far.

[jbea0064]

well i used the light to discover there is no light at all on the #2 valve. it felt a little funny, so i tried it on the #4 and blinking commenced on that location. any advice on the next step?

[jbea0064]

also, thank you for keeping me from spending $ and doing work it didn;t need. i appreciate that.

[smj999smj]

Since it is not "firing" the #2 injector, it explains why you are getting the P0302 trouble code. Turn the key "on" and use a 12v test light to check for power at the #2 fuel injector harness connector. If you have power, then either the ground wire between the injector harness connector and the ECM is open or the driver in the ECM is bad (meaning a new ECM will be needed), or you have a poor connection, likely at the ECM harness connector. So, if you have power, you'll need to unplug the ECM and use an ohmmeter to check for continuity with minimal resistance in the circuit between the harness connector and ECM. Also, make sure there is no continuity between that wire and any chassis ground point. If the circuit is open or shorted, you'll need to trace the circuit and find the open or short. If the circuit's good, inspect the pins and terminals in the harness connector, plug everything back in and start the engine. If you still have no firing of the #2 injector, replace the ECM. If you should check the connector with the test light and find there is no power to the injector, you'll need to trace the injector power circuit back to the problem. Again, refer to the factory service manual.

[jbea0064]

i appreciate it. i will be in meetings for the next 8 hours, so i won;t be able to do anything until tonight. i went to review the manual to discover that link is not for the full manual. it looks like i may need to pay th e$ to get the full version as i still have not found a full verison.

[jbea0064]

Man this is frustrating,
I have tested the working injector plug and it shows 11.3v the not working one shows 11.2v but the noide will not light up on the nonworking injector harness plug. I dont understand why the light in not lighting if the plug is getting 11.2v?

Any ideas. I test resistance against the working plug and they are the same. they both have a constant ground when not running.
They test with the meter as both getting the same stuff. I just dont know where to turn next or what to test next?

[jbea0064]

Is the ECM the same thing as the ECU?
I can get a used ecu from a junkyard for 200. You think it would be worth trying or should I take it to the dealership (i am not huge fan of dealers but they would know how to diagnose this gremlin) to have it diagnost?

[smj999smj]

Even if it gets power, it will not flash the noid light unless the other wire in the circuit is grounded (the ECM, which is the same as an "ECU," pulses the circuit to ground via an internal driver). The first thing I would do is disconnect and reconnect the ECM harness connector to see if re-seating the connector corrects a possible bad contact. If that doesn't work, you would need to unplug the ECM and injector and test the circuit between the injector and ECM for continuity. There is no sense spending money on an ECM unless you know the circuit is good.
NissanHelp.com has service manual chapter downloads in their "knowledge base" section for free. Nico Club's website also has free Nissan service manual downloads, but they are in .rat format, so you will need a program like WinZip to extract the files.