# 2 cylinder misfire i changed # 2 injector plugs wires roter egr light is still on does the vent breather have any thing to do with this problem nissan frontier 2004 xe

If you have already checked the spark plugs, plug wires, fuel injectors, and distributor and are still experiencing a misfire in cylinder 1 and 2, here are a few more things you can check:

1. Compression: Check the compression in cylinder 1 and 2 using a compression tester. Low compression could cause a misfire in one or both cylinders.
2. Vacuum Leak: Check for a vacuum leak by inspecting all hoses and fittings for cracks, damage, or looseness. You can also use a smoke machine or propane torch to locate any leaks.
3. Ignition Coil: Check the ignition coil to ensure it is functioning properly. You can do this by swapping the coils from cylinder 1 and 2 with the coils from another cylinder and see if the misfire follows the swapped coil.
4. Fuel Pressure: Check the fuel pressure to ensure it is within the manufacturer's specifications. Low fuel pressure can cause misfires.
5. EGR Valve: Check the EGR valve to ensure it is functioning properly. A malfunctioning EGR valve can cause misfires.
6. PCM/ECU: If all other components have been checked and are functioning properly, it is possible that the PCM/ECU (Powertrain Control Module/Engine Control Unit) may be faulty and may need to be replaced.

It is recommended to perform these checks in a methodical manner to narrow down the cause of the misfire. If you are not comfortable performing these checks yourself, it is recommended that you seek the assistance of a professional technician.

codes p 0300 through refer to misfires on each cylinder with the end number ( 301 is no 1 cylinder , 302 is no 2 cylinder ans so on)=== causes --engine mechanical fault , ---wiring---ignition/ fuel ---injector/s---ECT/ MAF sensor/s ---ECM
most misfires are from injector faults like dirty/blocked tips, low fuel pressure , no pulse or problem pulse from ECM rather than plugs and wires and coils
codes p0171 refers to system to lean bank 1===causes ---intake exhaust leak---air system---maf/vaf sensors ---fuel pressure / pump---injectors ---heated oxygen sensor ( HO2S)
code p 0172 is system to rich-====causes ---intake blocked ---EVAP cannister purge valve ---fuel pressure --EGR system---injector/s ---HO2S
couple these two codes with the misfire codes , I suggest you look at the injectors, fuel pressure (too low) from EVAP problem not venting tank, fuel pressure regulator, EGR system

the misfire could be the distrubiter cap also could be bad...tha cap is where the other ends of the spark plug wire go

Might be dirty injector or burned valve. Check the connector on the injector. If good, run a compression test on all cylinders. If compression is significantly lower on #3, the head will have to come off. If compression is good, pull up the injector rail with injectors and wiring attached. Watch the injectors spray as someone cranks the engine.

Without testing we would be just guessing . Hook up a spark tester to # 3 cylinder plug wire , is there spark ? Is the fuel injector for that cylinder squirting fuel , they make tools for checking this . Hook up a fuel pressure gauge an fire the injector , does fuel pressure drop. Could be a engine mechanical problem , compression test . Videos on youtube showing how to do these test's .

Dirty fuel injectors. Computer will show misfire on the cylinders that are malfunctioning. If injector cleaner in tank won't clean them, pull them all out and have a professional take them apart and cleaned. Each injector has a screen in it that can get plugged up. Think about Bro, all other stuff has been renewed.

The only thing left is a bad injector or possibly a valve not properly seating. Those particular engines do tend to have injector issues.

Is this the 2.4L? If so, I bet the Exhaust Gas Recirculation (EGR) valve passages are clogged. Likely has 3 of 4 EGR ports clogged, sending all EGR flow to the #2 cylinder. Check if it still has 8mm plugs in each runner for EGR transition passages. If so, remove those plugs to clean the EGR passages.
Hope this helps. Good luck!

OBD II 300 Random/Multiple Cylinder Misfire Detected

When the misfire monitor detects a misfire, it will trigger the check engine light with the specific cylinder number as the last digit in the P030X code. For instance cylinder 1 misfire is P0301, cylinder 2 is P0302 etc. In this case we have either multiple cylinders misfiring, or the computer simply can't determine the specific cylinder, and as such we are left with the P0300 in computer memory.

Possible Causes:

Fuel injectors, related wiring, sensors and computer issues
Running out of gas, or poor fuel quality
Evaporative emissions system (EVAP) concerns: fuel vapors leaking into engine
Incorrect Fuel Pressure
EGR system concerns: leaking EGR valve or restricted ports
Base engine concerns: low compression, valve train problems and timing issues
Ignition system concerns including, but not limited to:
Faulty spark plugs
Faulty coil or related wiring
Ignition module or related wiring issues
Ignition related sensor faults or wiring issues