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I have a miss in number 4 cylinder on my 98 altima. Ive checked compression and it is 180 pounds, put in new fuel injector, new plugs and new plug wires and distributor cap and rotor.
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Check these three things in the misfiring cylinder: spark, gas, and compression. One of them is wrong or missing. For spark check the spark plug and wire. Make sure you have spark on the plug wire, a strong blue spark. For gas, the fuel/air mixture may be wrong. Does the fuel injector pulse, putting gas into the cylinder? Possibly you may have a leaking injector or a clogged injector.
If gas and spark seem okay, you need to check compression in the cylinder. Low compression will cause a misfire. If compression is 20 or 25% lower than adjacent cylinders, that could be causing a misfire. For example, say numbers 1 and 3 cylinders had about 150 psi compression. 80% of 150 = 120, so if cylinder 2 is 120psi or less, that could be setting the misfire code. Low compression can be caused by valves not seating well, or bad piston rings, bad head gasket- something in the combustion area of the cylinder is losing compression.
Always start with basics. Check compression on each cylinder should be within 20 pounds of each other check manufacture spec.( Make sure new plugs and coils are firing) If thats all good get vacuum gauge on intake and check vacuum (18-21hg) if low check for vacuum leaks or plugged catalytic converter. If good go and fuel pressure and injectors. You have to do it systemmatically to narrow it down. Good luck.
Friend, replace the fuel injector on that cylinder. That's really good compression and nothing at all wrong with the valves. That misfire is what we call a dead cylinder and it is repairable. #4 cylinder is the front cylinder on the drivers side. You must remove the coil pack, disconnect vacuum lines from the front of manifold, pop all the electric connections off, remove the 6 bolts securing the upper plenum chamber and lift it off the manifold. Unclip the fuel injector wire connection from #4 injector at this point. There are small bolts securing the fuel rails to both heads to remove so the fuel rails can be pulled up to get to the fuel injectors, the will stay in the fuel rail when lifted, and it's a stiff removal because of the rubber O-rings holding the injectors in. When you have that up and able to get to the injector, just twist it out of the fuel rail, put the new one in it's place after a light lubricant is put on all the O-rings on top and bottom #4 and all the lower O-rings that are exposed, guide all the injectors back in their ports and push them all down until the fuel rail mount brackets are in position for the bolts and put the engine back together.
engine missing could be caused by faulty spark plugs and wires,bad ignition coils,dirty fuel injectors,leaking egr valve,low cylinder compression,intake vacuum leaks.many things will cause engine to miss, first do minor fix,replace distributor cap and rotor,replace spark plugs and wires,clean fuel injectors,replace fuel filter and air filter,if this minor tune up dont help engine and engine still missing, do a vacuum test and compression test to check condition of engine.engine could be worn out have low compression by worn valves and pistons rings.
simply swap out one injector for another (I simply say if you there already just replace the injector...its a possibility that it is a bad or plugged up fuel injector. on number 4 cylinder. if spark and fuel are ok, its the injector doing this. good-day !
CHANGE FUEL FILTER AND CLEAN FUEL INJECTORS,CLOGGED FUEL INJECTORS WILL CAUSE ENGINE TO MISS, MAKE SURE SPARK PLUG GAP IS 0.060, LEAN MISFIRE FROM WEAK FUEL PUMP,CHECK FUEL PRESSURE SHOULD BE 40 - 50 PSI. IF EVEVY THING CHECK OUT OKAY,MISSING PROBLEM COULD BE LOW CYLINDER COMPRESSION OR INTAKE MANIFOLD AIR LEAKS.DO A COMPRESSION TEST IF NECESSARY.
First check plug and make sure the right plug for this vehicle,make sure that the heat rating for this plug is correct. Your problem could be a wrong heat rating plug been installed. Also make sure that the misfire is due to a bad plug and NOT a bad injector or injector wiring or uneven compression or even bad coil. Check injector wiring and make sure it not shorting or broken. To check injector pulse use a NOID light can be bought at almost any auto parts store like Auto-zone etc. Also compression can be checked with compression guage. A rule of thumb to go by is if any cylinder has more than 10 PSI in difference in compression there is a problem like a burnt valv etc. Here is a n example cyl# 1 170psi cyl#2 176 psi cyl#172psi cyl# 4 150 psi, there is a problem with cylinder # 4 and will cause a miss from cylinder #4. Good luck and thank for using FIX YA
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