P0300 codes

CASEYREHRER

MEMBER
2000 TOYOTA TACOMA
3.4L
V6
4WD
MANUAL
131,000 MILES

My truck hasn't been running well lately. At first it felt as if the clutch was slipping, it would shake a little in all gears, even when it was above 2000 rpm. Feels like a serious loss of power. A few days ago, my engine light came on, so I checked the codes, and they were p0300, p0306, and p0120. The p300s are cylinder miss fires and the p120 is throttle position. The p300 indicates that it is more than one cylinder misfiring correct? Iv replaced ignition coils and spark plugs before, I was wondering what would be the best way to go about this? Obviously I'll replace the 6th cylinders ignition coil and spark plug, but how can I tell what other cylinder is miss firing? And how many ignition coils/spark plugs should I buy? Just two?

1 Reply

HMAC300

MECHANIC
48,601 POSTS

Misfires are hard to diagnose. Check fuel pressure with a gauge auto parts rent it as that may be the cause and check for a vacuum leak as well, cracked hose et. These are best left to pros as you can end up dumping a ton of money into parts that good yet replacing them because you thin they are bad. You need to freeze frame and check voltages on sensors. Got to how to repair to see how to check fuel pressure. Should be 38-44psi and not drop for 5 minutes.