What does radom miss fire mean

nissan
sentra

#1

my 2002 nissian sentra has this code how do u fix it


#2

It means that more than one of the sparkplugs are not firing. It probably has plugs or plug wire(s) going bad. Have you noticed it running poorly?


#3

Plugs/wires are a good place to start but it doesn’t exhaust the possibilities. Actually, since it is random I’d be more inclined to think of something that feeds all cylinders (e.g. distributor/coil pack - I dk the specifics of the ignition system). There are also fuel system issues that could be a factor as well as mechanical engine problems.

So there is no “how do u fix it” without first diagnosis.

You might give people some more info. E.g. how many miles are on this car? How old are the plugs and wires? Fuel filter? Air filter? The basics always come first and if any maintenance is out of date should be done regardless of whether it fixes the problem or not.

I’m assuming btw that your check engine light is on and you have a P0300 code. Any other codes appear?


#4

I have never heard of that code before, but a random misfire on a car generally suggests a lean air/fuel mixture. I would look at the air tubes between the mass air flow sensor and the throttle body. Remember that they generally crack on the bottom, so you have to pull them off to examine them. Also look for vacuum leaks in the vacuum hoses attached to the intake manifold. A leaking exhaust gas return valve or stuck open PVC valve can also cause a vacuum leak at idle that may be hard to spot.

Can you perceive the misfire or is the only symptom the code? Is it at idle or when accelerating? If it is at idle, look for a vacuum leak. If it is when accelerating, look for causes for a weak spark, or consider the age of your spark plugs.


#5

i have changed the plugs this is the only code that it has in it the first code was for the crank shaft pos. senor i have changed it sometimes it will start like it is brand new then it will turn over like it is flooded you can take the plugs out and they smell like they are flooded i have changed the plug boot do u think it might be the coil it has four one for each plug thanks for everybodys help


#6

Did you inspect the wiring for the CKP sensor? The sometimes starting, sometimes misfiring sounds like a prime candidate for this kind of problem - loose/broken with intermittent connection.


#7

Can you detect any actual mis-fire under hard acceleration?? You will feel a jerky stumble instead of smooth acceleration…Sometimes computers and sensors are WRONG!!


#8

i havent checked the connection but when i first changed the ckps it started goood form about a week then it stated doing the same thing again


#9

The connector to the CKP might have some dirt or corrosion. Disconnect it and clean it with some electrical contact cleaner. See what the contacts look like. A bad connection to the CKP can cause the random misfire code.


#10

My girlfriend has the same problem on her SpecV right now. Sometimes the code is random misfire, sometimes it’s for Cyl 2.

All the filters are new and vacuum hoses have been checked. The current thought is that there could be a leak in the head gasket between Cyl 1-2. They should be able to do a pressure test and diagnose this pretty quickly right?

The problem is intermittent and does not seem to be tied to engine temperature, road speed, humidity or ambient temperature.