One of the first things to do is perform an ECU code readout with a portable scan tool to see if any fault codes are set. The tool can be purchased at most auto parts stores. Post the actual codes here on the forum so that we may be able to help you further. If there is one or more fault codes set, they can help point to the malfunction. If you have a copy of the FSM for your vehicle, the code readout procedure is described there along with a listing of codes. You can download a copy of the FSM from this web site:
Nissan and Infiniti Service Manuals or
https://diyservicemanuals.com/. The section EC.PDF is the one you need to read.
The idle misfire (rough idle) could be due to any of the following:
* Dirty spark plugs. What brand of spark plugs are you using? You should be using OEM NGK plugs; other brands such as Champion or Bosch many times cause driveability problems in Nissan engines.
* A cam position sensor may be marginal.
* Incorrect fuel pressure. Tee-in a temporary fuel pressure gauge at the output side of the fuel filter. The reading at idle should be 51 psi.as follows:
* There may be a major intake system vacuum leak To check the intake system for a vacuum leak, attach a vacuum gauge to a full vacuum source. With the engine fully warmed up, the reading at idle should be 18 - 20 InHg. At 3,000 RPM, it should be 21 InHg. If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. The gasket may have failed; spray a water mist at the gasket to see if the gauge reading changes. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps.
* Dirty fuel injector(s). Run some good injection cleaner, like Techron, Redline SL-1 or BG products 44K, through the system; give the cleaner about a week or two to do it's job.
The engine noise could be one of the following:
* - If the noise is really a lifter tick, by using the FSM, you can very easily check the valve lifter clearances.
* - It could be a low oil pressure issue. You can check the pressure very easily by installing a temporary mechanical oil pressure gauge. You would remove the oil sensor which is located next to the oil filter and install the mechanical oil pressure gauge in it's place; you may need to get an 1/8 BSPT to 1/8 NPT adapter to hook up the gauge. With the engine fully warmed up, the pressure should be as follows:
idle - at least 14 psi
2000 RPM - 43 psi
* - The timing chain assembly could have a worn-out chain guide.
* - There could be a damaged rod bearing.
* - It could be a bad water pump or alternator bearing.