Also, I suspect the K&N filter was probably supposed to be oiled. If the previous owner didn't oil it or when they cleaned it they failed to oil it again. Dry K&N filters allow dust and dirt into the engine, which scores the cylinder walls and rings. Leading to low compression.
Stop buying parts and fully diagnose the problem first. Then decide if the car is worth the repairs. My guess is that you're looking at an engine rebuild. Looking like around 2 grand. A used engine (with 90 day guarantee) will run around $1200. THAT is why you fully diagnose the problem before you begin throwing parts at it.
Hope this helps.
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It's time to take the car to a Nissan Dealer to fond out which of the OTHER ignition coils aren't firing. Too much oil on the air cleaner will foul the mass air-flow sensor.
OK thank you guys for the answers but I forgot to mention it was every where p0302,p0304,p0306 I got the p0306 more than anything until I replaced a vaccum tank that was broken that helped the misfire a lot then it just went to p0300 then I replaced the number 4 coil because I broke it trying to remove a spark plug that has brought down to a p0304 and if I replaced one injector don't I have to replace them all which would cost me a lot of money
All of the plugs were sooty black, but only a misfire on selected cylinders. I'd make sure that each plug has good spark while out of the cylinder.
http://www.nationaltoolwarehouse.com/Sta...
I'm suspecting a sensor is telling the ecu that there's a lean condition so it's pushing more fuel into the cylinders than needed.
But, I could just be blowing smoke out my....
You have concentrated on plugs and coils how about fuel injectors now. And don't go buying any just yet move the number four to another location to see if the code moves. Don't take to long to cure this because your cat is catching hell with the flood of fuel coming out.
I don't know about this but i am interested to know about this....
ok so i bought a 2003 nissan maxima with 135k and it had a p0300 it had a preformace k&n filter on it so i though someone might have installed it wrong or what ever so i bought the car cheap. i have replace the k&n filter with a stock 2000 nissan maxima air box with new filter i got from the junkyard it helped the misfire calm down a little then i bought the car to a machanic and he said because of my hard starting it could be a cam senor or crank senors so ive replaced that still no luck then he pulled out the sprak plugs and they were sooty black but when i bought the car i checked and they were brand new so i swap them out with ngk platium sprak plugs then help a little but still same problem. i had a p0302,p0304,p0306 when i clear the p0300 but usally its all ways a p0300 any ideas its been a month and im still driving like this.
SYMPTOMS:
hard starting after 20 mins of sitting
i can smell gas from the driver seat when i start the car and open the window
exhaust air isnt smooth but in pops
getting like 14-15 mpg in city
when stoped at a stop light i can feel the car misfiring
WHAT I HAVE REPLACED
front bay 3 ngk spark plugs cylinders 2,4,6
cylinder 4 coil
air box
cam sensor and crankshaft senor
coolant temperture sensor
battery
Video of it hard to start
http://youtu.be/puJPuPV0Kx4
Video of me checking the gasket and rear spark plugs and my discovery
http://youtu.be/aJIAwn2uEYg
