My wife's 01 Altima started idling rough 2 weeks ago. No CEL was on atthe time, so I changed plugs, wires, rotor/cap, fuel filter, air filter. Still idles rough. Took it to a garage (didn't have scanner at the time) 'cuz the CEL came on and they said 2 codes came up; front O2 sensor and #4 cyl misfire. Guy checked the 4 wire and said the retention clip to the plug terminal was loose. I replaced the wire and sensor, same results. Thru this forum I read all the rough idle posts, and since then have changed the Engine Coolant Temp sensor, removed and cleaned the injectors, swapped #4 injector and plug w/#1 cyl. Spark looks weak on plug 4. There is no sign of oil in the disatributor and the code reader I bought sez 2 codes (I erased the previous O2 related). It reports now 2 codes:
P0304 Cyl 4 misfire
P0300 Multiple cyl misfire detected
I also ran the unlit propane torch around the intake and hoses looking for a vacuum leak, but none found. How can I isolate malf. this to the distributor or other component? No CEL is on at the present.
I am having the same problem with my 2001 Nissan Altima GXE. So far have replaced spark plugs, spark wires, distrib. cap and rotor. My code scanner was reading 100 and 304. I replaced the MAF sensor. Now just getting cylider 4 misfire. My plugs are about 1 1/2 weeks old. I am getting carbon buildup already which indicates too much fuel. I'm thinking o2 sensor. Have you replaced yours? Both or just one? There is another o2 sensor after the catalytic converter. I'm still having the problem though. Anyone with any ideas please help!
I had someone recommend taking carburetor cleaner and spraying the gasket on cylinder 4 which was the one misfiring for me. When I do, it clears up for a few seconds and starts again. Obviously the gasket is leaking. Might want to try on yours.
I'm having the same problem with my 2001 Altima 2.4L. I have a engine code PO304, # 4 cylinder misfire. I sprayed some carb cleaner in the area of # 4cyl intake and it definetly changed the idle. I noticed some bubbles in the puddled up carb cleaner and figure that's air getting out as well as carb cleaner getting sucked in. This car has 92,000 mi. on it and it's probably time for gaskets, hoses or anything else made of rubber or material that can disinegrate to start doing just that. Plus, torques on bolts start to loosen over the years and miles from shaking and heat-up/cool-down cycles. So, I'm off to R & R the intake manifold and gaskets. I'll let you know how it turns out.
When you check your distributor you have to remove the cap then the rotor then the next cap to see if there is oil. I had a same problem on mine found oil under the second cap . Replaced distributor runs great. Seal goes out on the cam of the distributor.
I had the same problem with a 94 Altima. Seems the 4th cylinder runs hot. It will eventually burn through the gasket. Try this. Have someone put the car on drive and while the car is on drive it should start running rough. Spray brake cleaning fluid on the back side of the engine (by the #4 cylinder) and see if the rough idleing stops for 2 seconds or so. If it those stop you have a blown gasket thanks to that hot #4. Many people have this same problem looks like Nissan screwed up this engine with out knowing! HOPE THIS HELPS GUY AND GALS!!!!!
I have a 98 altima that did the same coding back in 2005. After spending much time and money, I took it to a mechinic who found intake gasket had blown an eighteth of an inch cap over the # 4 cyl. I went through the injector replacement - plugs and wires - even cabibalized another distributor - to no avail.
engine misfiring can be several things. first check plugs and wires. next check timing belt may have jumped a tooth or worse worn to the point it is about to break. Obviously check gas for water in tank. Especially if you like to run tank very low before putting in more gas. What happens in this case is condensation forms on inside of tank and forms in bottom of tank. Does misfiring only happen when tank gets to a certain level? but filling up and it goes away? suspect water in tank.misfiring can be as simple as way past due for tune up ,fuel filter, bad plug wire.You did not say what the engine size and if it had a distributor or was distributor less.If it has distributor then look at cap and rotor button. If distributor less could be cam or crank sensors acting up. But remember keep it simple, if you have not given it a tune up in a long while start there, 90 % of the time that fixes it.