Hi!! I changed all spark plugs, all ignition coils, all 4 fuel injectors, i have no vacuum leak, but…

Nolj

Hi!! I changed all spark plugs, all ignition coils, all 4 fuel injectors, i have no vacuum leak, but my 05 Nissan Altima's engine is still misfiring, what should I do?

Comments (5)
No. 1-4
BH1
BH1

Do check if the sparkplugs are getting enough current, bad wiring can prevent from getting the current for spark and cause misfire. Scotty has a video for checking sparks

Nolj
Nolj

It does it when I'm driving and on stationary?

Nolj
Nolj

Code is PO300,i checked everything already and they're fine

Naser Oric
Naser Oric

It is always annoying if you replace a lot of parts, but nothing goods happens. Since it is a 2005 Nissan. I would read the codes with a scan tool first. You can get a cheap one for 25 dollars that should work fine. Also, if the car runs on three cylinders it can misfiring like you said. So also check if you get spark at every cylinder/spark plug. If you have spark everywhere than I would check if each injector really sprays enough fuel. You can check this by removing the fuel rail and trying to start it with a piece of paper in front of it so you can compare the spraying. This is also eyeballing if all the injectors get enough fuel pressure. It could also be the fuel filter that causes there isn't enough fuel pressure. And check if an unplugged MAP-sensor will get it running better. Does it misfire only stationary or also while driving?