Why does my 1998 Nissan Frontier misfire when the motor is cold?

Question

I have a 1998 Nissan Frontier with a 4 cylinder engine with over 300,000 miles on it.  It's been running fine but it recently began misfiring when the engine is cold.  When I start the car it seems to run fine but when I try to accelerate hard (I have to enter a busy road with few breaks in traffic), it hesitates.  After about three miles, it runs fine.  Today, for the first time, the check engine light came on along with the hesitation.  The code is P0304 indicating a misfire in the number 4 cylinder.  What can be causing this?

Shellback · Accepted Answer

I would suspect it needs new spark plugs or wires, and a good tune up. Also with 300k on the clock you could have a sticking injector, bad ignition coil, obviously engine wear could be a tad excessive and the clearances tighten up as the engine warms up making it run normal.

Like I said if you plan on just throwing cash at an unknown issue I would start with new plugs and wires, reset the ECU and go from there.

Best bet is though take it to a good mechanic for a tune up and diagnosis! To avoid throwing money at a possible unknown problem.

auto m · Answer

What seem to be a simple operation like replacing spark plug may end up in a worst case scenario

These Nissan require a air volume relearn often enough after a simple procedure and it is a gamble as if the manual procedure will work so you need the Nissan scanner 

Now you know

D · Answer

Did it rain or you wash your engine. Maybe water went in the no. 4 cylinder spark plug.  Dry it off. Otherwise, spark plug, spark plug wire or fuel injector on number 4 cylinder is defective.

Why does my 1998 Nissan Frontier misfire when the motor is cold?

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