I used the search function but could not find an issue like mine. Here it goes.

2003 6MT Nissan Maxima 58000 mi
Recently I had a real rough start after a few weeks of the car sitting. All was fine at the time. A few days after on startup I had a misfire/rough idle for a mile or two and then it cleared. At this time the car threw a p300.I have since then been getting the same issue on a COMPLETELY random basis. Car will start and run like a top for a day or two, code clears. Then with no rhyme or reason I will have the same rough idle/misfires. If I keep the rpm's up around 2500 the issue is not noticeable and clears shortly. Changed plugs(oem) and inspected coils and all looks ok there. Premium fuel only. I am being told MAF, Camshaft/Crankshaft positioner or Fuel pump. Any ideas??

 

As per the FSM
MULTI CYL MISFIRE P0300 0300 2 X EC-300

POSSIBLE CAUSE
I Improper spark plug
I Insufficient compression
I Incorrect fuel pressure
I The injector circuit is open or shorted
I Injectors
I Intake air leak
I The ignition secondary circuit is open
or shorted
I Lack of fuel
I Drive plate or flywheel
I Heated oxygen sensor 1
I Incorrect PCV hose connection

Probably a bad coil / plug

 

Yea, I just changed the plugs and the coils look fine. If a coil went bad wouldn't I get a specific cylinder code?

thanks for the reply.

 

Not necessarily.

Test the coils, test the injectors. Those and the plugs are the three main reasons for a misfire.

 

I got a P0300 too, and I'm gonna be diagnosing it soon. I did a search, and couldn't find anything on testing injectors though. How do you test the injectors?

 

Ohm out the injectors. You're looking for 13.5-17.5 ohms. Also they should all be quite similar in resistance across the two pins.

10-14 ohms for the VQ30.

 

im going to be changing my plugs this weekend, will be checking the injectors as well. thanks for the info. for you 3.5 guys, i plan on doing the 04 rear valve cover fix, i dont know if mine is bad, but for 45 bux its piece of mind. do you need to replace the IM gasket, my IM was off once before when the headers went on the car, i dont want to skip any corners. thanks

 

I just got code p0300 and p0011 at the same time...My car is shaking and If I give it gas it picks up fine. It seems to mainly be a rough idle issue. Check engine soon light stayed on, then starts flashing over and over again.
I have 95,550 miles on the car...

Should I first go for the obvious = spark plugs?

2002 max = 6spd

 

I would, yes. Next step would be ohming out the coils and injectors.

 

This morning I started the car and let it warm up..I noticed the rough idle was not present so I took it for a spin. The car runs great again so I cleared the codes.

NOTE: I was going to change the oil this morning because yesterday evening I put a can of "engine restore" (6-cylinder), and within two miles of driving time, it threw those codes. I am thinking that had something to do with the codes being displayed so last night I took it for a 30 minutes highway spin and wonder if that made it correct itself.

 

If you're going to ask for help, you always need to mention anything you've done recently to the car. A can of that 'restore' crap is information that needs to be known.

 

I agree, but did not think anything of it until my trouble-shooting gear kicked in and then I realized, ah, ma'an I bet that restore stuff caused the codes to show up.......

 

i'm having the exact same trouble with the P0300 code.. i replaced all plugs, tested all the coils, and they are fine.. i did the pull test on the injectors already, and they came out good, but i'll do the OHM test... hopefully i can fit the OHM rods in there without pulling the manifold.. is the OHM test more reliable than the pull test?

 

What is a 'pull test'?

 

when you leave the engine running, and pull the plug on each injector/coil.. and if the engine starts to stumble, then that coil/injector you pulled is good because it was doing its job.. and if the engine keeps the way it was then that injector/coil is bad because it was never doing anything in the first place.. thats what i was told is a reliable test to see if isolate an injector/coil that may be giving you problems.. does that method have the same validity as testing it with an OHM meter?

 

Two entirely different types of tests. Disconnecting the coil/injector merely narrows it down to a specific cylinder, ohming out the injector tests to see if the coil in the injector is good (it could still be physically damaged/clogged).

Ohm the injectors, yes.

 

i'm gonna do this test.. is it the same numbers for the VQ35? also, where do i put what rods on the injector to test it?

 

The first set of numbers is for the VQ35 injectors.

You put the leads across the two pins on the injector.

 

ok.. does it matter which pins the negative and positive leads are attached to?

 

No.

 

Wyche89,

Did you ever figure out what was causing your rough idle? I've been having the same random rough idle problem for about 6 months. My car's symptoms usually occur with a cold start where the ambient temp is in the 30s. The rough idle will last maybe 1-2 minutes and then completely goes away (usually the check engine light just flashes for part of the time and then goes out). After it goes away, the engine runs strong, like normal the rest of the ride/day. And it doesn't always happen every time, just sometimes.

When it first started, it threw a code for "Cam position sensor". I talked to DaveB at Southpoint Nissan and he said there are 3 sensors that tend give people fits (2 cam position sensors and a crank position sensor) and suggested changing all 3 to start. I ordered from him and replaced all three. It didn't help. I still get the rough idle randomly and just Friday, the check engine light flashed and then stayed lit. I went to Autozone and they said P300.

BTW, I have a '03 SE 6speed with 64K miles and it is pretty much stock.

Pete