2000 nissan xterra knock senor and plug 5

po328 is a knock sensor code ,0174 &0420 are emissions codes. Possibly a faulty knock sensor throwing out the timing, It may just have a vacuum leak causing it to run lean, affecting the timing causing knock sensor code, Scan for live readings, ck knock sensor, o2 sensors, A/F ratio & converter,clogged injector ect. Good luck
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could be many things,but i'd check airflow meter first,then fuel pressure and volume

Trouble Code: P0304

Cylinder 4 Misfire Detected

Possible Causes:


Air leak in the intake manifold, or in the EGR or PCV system.Base engine mechanical fault that affects only Cylinder 4.Fuel delivery component fault that affects only Cylinder 4 (i.e., a contaminated, dirty or sticking fuel injector).Ignition system problem (coil or plug) that affects Cylinder 4.Trouble Code: P0505

Idle Air Control, Auxiliary Air Control Valve Circuit Malfunction

Possible Causes:


IACV-AAC valve control circuit is open or shorted to ground.IACV-AAC valve control circuit is shorted to system power (B+).IACV-AAC valve is damaged or has failed.PCM is damaged or has failed.

Mass air flow sensor might be dirty or failing.
Clean sensor when cold with mass air sensor cleaner only.
that controls the throttle opening and closing.

You got a timing chain
Injector cleaner,in my opinion is a waste of money
PO306 could be a missing coil on cyl #6,still should start
PO325 Knock Sensor-most likely okey
Plugs,cap and rotor,will not prevent it from starting,it used to run with old parts, before the current problem!

I suggest you make sure you got the plug wires on correctly and number them with a ball point pen,on both ends.
Make a diagram of the dist cap wire locations.
Check out the TPS Sensor and make sure you have all intake ducting in place. You need the MAF Sensor in the system to run have it run
Have you checked fuel pressure? The pump may be going bad

CODE PO505 - IDLE SPEED CONTROL SYSTEM MALFUNCTION.SOUND LIKE IDLE SPEED CONTROL ELECTRICAL CONNECTOR IS DISCONNECTED OR HAS FAILED.

Sometime just need tune up.

Sounds like you need a valve job

0340 is camshaft position sensor and the other 0325 is the knock sensor. Chances are you need to replace the sensors and good to go.

It's the valley of the engine underneath the intake manifold. It's about an $800 job because the top of the engine has to come off. However, unless you have a supercharged xterra it shouldn't effect performance. Also, the knock sensor will not trip the check engine light, as it does not indicate a primary problem, so if your light is on you should have another code that should be fixed first.