CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Misfire

have a 1997 nissan pickup 2.4 liter engine check engine light came on code say number 2 cylinder misfiring put in shop. they say that they can’t get to misfire.truck run great.just that light keep coming on with code (p o 302)

So whats the issue? The engine is running fine or runs fine when its in the shop and still throws a misfire code? The engine computer will know of a misfire when one occurs …FAR before any mechanic will. If the light is coming on …with the same code and same cylinder misfire number…I would simply replace the spark plug and THAT coil on the #2 plug… Hopefully you have individual coil over plug coils…so that you can change JUST the #2 coil and nothing else…as some vehicles have coil PACKS…grouping 2 or more cylinder coils together and forcing you to change out a perfectly good coil thats stuck in the pack with a bad one… SOOO…I’d change the #2 spark plug and its coil and see what you get…

Blackbird

honda blackbird nissan 2.4 liter don’t have a coil.and i did change all spark plugs and wires.

Well, go buy a new coil and install it !

The nissan 2.4 does have a coil, its inside the distributor. That little bump in the top of the cap that goes from the center of the cap to the edge is the built in coil wire. But your problem is likely a fuel injector that is partially clogged or maybe even leaking. Try a fuel system cleaner in your gas. Techron is one of the best for this.

I got to thinking about this after I posted, did you replace the distributor cap? If you didn’t, you might want to remove it and wipe down the inside. Sometimes they can build up carbon tracks inside them that can cause a little misfire. Wiping the inside with a dry rag usually removes these.

Heck, I’d just change the distributor cap and rotor rather than trying to wipe the cap out. I agree about the carbon tracks, they for high resistance shorts, but caps & rotors are cheap!

It’s 15 years old! How many miles on it??? If you are happy with the way it runs, then just run it!

A check engine light is no reason to spend hundreds of dollars if you are happy with the way the truck is running…It is NOT a crime to ignore the light…

But, Caddyman, if your in a jurisdiction that does emissions testing, that light on means you don’t pass. If it is as easy a fix as a distributor cap, rotor, wires, and plugs on a 15 yo truck, all for less than $100, you still come out ahead.

Ignoring the check engine light is to me abalogous to removing the batteries from your smoke detectors. It renders an important warning system totally useless. I recommend against it.

I would run a compression test. A cylinder that is dropping abnormally low can create a situation in which the spark plug may intermittently foul and misfire to some degree. It may clear itself up for a while only to return again at some point.

If the compression is good then the possibility of an injector or injector wiring circuit fault should be considered.