I have an 02 maxima (stickshift) and today I went out to start my car and noticed that it was running crappy, misfiring when I first started. I never noticed it before because I remote start my car so this has probably been going on for a while. I got the P0300 Random/multiple cylinder misfire and the CEL was flashing. Now as the car warmed up the misfire disappeared and the car ran after thereafter. So being that not specific to a cylinder or so the code says, it's gonna be kind of hard to diagnose, plus when it warms up it disappears.

Does anybody have a clue as to what it might be or experienced this same issue? Anything specific to my year and model that goes bad?
Thanks in advance

 

First things first, start simple. Look at plugs and ignition coils. That's one of the most common causes for misfires.

What I like to do sometimes as a diagnosis is let the engine idle, and remove the coils one by one while the car is running. Each time you remove one, you'll notice the engine run like total sh*t. Plug it back in if it does and move onto the next. If when you remove the coil you notice NO change, you obviously have a bad coil/boot. I'd say start small and change the plugs though.

 

[QUOTE=Stru;8758821]First things first, start simple. Look at plugs and ignition coils. That's one of the most common causes for misfires.

What I like to do sometimes as a diagnosis is let the engine idle, and remove the coils one by one while the car is running. Each time you remove one, you'll notice the engine run like total sh*t. Plug it back in if it does and move onto the next. If when you remove the coil you notice NO change, you obviously have a bad coil/boot. I'd say start small and change the plugs though.[/QUote/]

Actually plugs are fairly new, coils are very old. Problem is this goes away minutes after the car warms up, but I'll check the coils anyway for loose connections, who knows
thanks for your input

 

The 300 code shows up first then you will get the code for what one failed like a 305 etc either wait it out or do the coil unhook procedure to find it now and Do Not buy aftermarket coils spend the extra$20 and get oe ones or face the problems

 

I do find it odd though that it happens cold but ok when warm. My experience with other cars has been that when coils get hot, they start misfiring. But thanks for this infoI'll unhook before its too late. Was gonna take my car on a 350mile trip tomorrow, guess not

 

P0300 code can also appear if one has allowed their oil level to get to low, which then allows for the sludge and other impurities sitting in the pan to get pushed up into the engine and thus going into the Variable Timing Solenoid. The VTS has a very narrow passage way that can become clogged which puts the timing off resulting in the p0300 code going off. It can take several oil changes and filter replacements to get this passage way cleared up once again.

 

Interesting info. I did let it go kind of low in oil but that was maybe 3 months ago. This misfire just happened. I'll add this info to my library
thanks

 

i have a p0300 code also it comes on and off like 10 percent of the time. also it use to have the cylinder 2 misfire code but i changed the coil with a oem and i still get the p0300 code but no longer cylinder 2 idk if another coil or what. i know i may need to replace my valve cover and gasket cause my dad was was just inspecting the car and saw a lil oil on the spark plugs. if i still have my maxima by the summer i will replace the valve cover with the 04+ vc and gasket for my 03 maxima and minus well change all the spark plugs. i guess ill change the rear since i have to install my nwp spacers anyway itll just be part cost and ill do the labor

 

When I changed my rear valve cover and plugs as well as installed NWP spacers I encounter the p0300 code about three weeks later. I did find my oil level down to low and had read about this clogging of the VTC. I purchased a Bootle of Auto-RX and followed the internal engine cleaning procedure and have not had any further issues. Auto-RX works to breaks down the internal gunk and dirt to a liquid form which is then cleaned up by the oil filter. Even though you allowed the oil level to get low 3 months ago you could have still pushed engine gunk up into the top end which may now have built up to block the passes way and bring on the p300 misfire code.

Was just a thought I would share with you as a possible cause and how I found a way to resolve it.

 

Thanks guys for these last 2 posts. I had actually replaced my rear valve cover last summer and never got a 300 code ever before. And actually since that time that I got the 300 code I haven't seen it since. Always been outside to start my car and so far so good. So this is one of those odd situations.

 

i think it was oil on your plugs as you stated before, perfectly plausible

 

Well I had replaced the plugs right after I did my valve cover seals.
Although in this car and I'd like to see what every one else has to say about this, Everytime I took the plugs out the threads on them are kind of wet as with oil but the electrodes are dry and looking good. I know these cars burn oil and I do have to put a quart in about every 1500 miles and I'm using full synthetic. I was thinking about switching back to normal oil to reduce the oil burn but haven't yet.

 

P300 can also be a bad injector. Its very unlikely but keep that in mind.