Hi guys,

Been trying to troubleshoot the infamous P0300 misfire code for my 2003 Maxima 6 speed. Used the search function and read through TONS of threads and possible fixes. Engine vibrates like crazy at idle once at operating temperature. However, it's super smooth once at highway speed and experience no loss of power or pick up. I also have the FSM and have been trying to follow that.

Mods are I/H/E and NWP Block Plate. When I rev the car at idle or do a hard 1st gear or 2nd gear pull, a lot of smoke comes out from the exhaust. Looks blueish/grayish from my rear view mirror and then it disappears. Car does have 215k and I'm leaning towards a bad engine at this point but I'm trying to rule that out if possible.

Here's what I did so far:
Cleaned MAF, changed PCV valve, changed crank position sensor, changed both cam shaft sensors, checked fuel injectors - all six makes the tick tick tick sound with a screwdriver, changed all six coil packs, changed all six spark plugs with NGK Platinums. Tried finding a vacuum leak by spraying brake cleaner around the vacuum lines but couldn't detect anything. Still get P0300 and shakes a lot at idle. Can it be a defective A/F O2 sensor?

Any feedback will be appreciated.

Thank you!

 

I am hoping that you replace the ignition coil with Genuine OEM not the aftermarket , including the Camshaft and crankshaft position sensor.
Possible causes
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
Good Luck

 

It can be a number of things like stated above. However, I am going to make a guess that the problem is coils.

 

Also check the throttle unit. It may sound off base, but if they go faulty they can screw with AFR, which can potentially cause the misfire issue. Beyond that, I would be looking at fuel related items, especially the filter, based on the smoke you're describing. Could be the pump itself, but you can check all of them at once since they're interconnected.

 

Hm..I did go with aftermarket coil packs and all three sensors. I still have the other coil packs that I removed. Not sure of the brand though. As for the O2 sensor, are you talking about the ones that plug into the front header and rear header? I have an O2 sim for the secondaries after the headers install.

Also considering a flywheel issue as well though it's last on my list. I do need a new clutch and was thinking about replacing the flywheel while everything is out.

If it can relate to AFR, will it also relate to the A/F O2 sensors as well? I'm just curious because I am assuming oil is leaking into somewhere and once I go WOT, it burns the oil and creates a big plume out of my exhaust.

 

It's possible, but I really think you need to get a compression test done. I'm pointing towards checking fuel related items in the hopes that you'll find the problem and it therefore won't be the problem I really think it might be. Which is pistons rings. If you're losing compression in one or more cylinders it can cause everything you're describing. I would recommend getting a compression test and leak down test done to make sure.

 

i also have a very similar problem. oem coils and chrankshaft position sensor. ne plugs, cleaned maf. it only throws the p0300 AT IDLE, otherwise car runs fine down the road. checked for vacuum leaks, no dice. but. watching the fuel trims on torque pro, both banks continously escalate in leaness until the ecu corrects it around +20, back down to 0.0. i want to say theres a vacuum leak small enough that i cant find it. only other thing is after i drive the car for around 30 minutes when i shut it off there is a humming noise that comes and goes like every other 30 seconds in the rear of the car near the gas tank. im unsure if the evap system is trying to release pressure or build it. ive read that a saturated canister can cause p0300 as well.

 

Sorry, my personal view your problem is the aftermarket coil and sensor.

Oxygen Sensor:
Front sensor 1 Bank 1 (near the firewall)
error code:0031 0051 0130 0131 0132 0133 0134 0135 1143 1144 1148
Front Sensor 1 Bank 2 (near the radiator)
error code:0032 0052 0150 0151 0152 0153 0154 0155 1163 1164 1168

Kindly give me favor replace your ignition coil 1,3,5 with OEM Genuine parts and replace camshaft and crankshaft sensor with oem genuine parts. Ignition coil 2,4,6 replace it with any brand you prefer because its accessible.

 

Thanks for your input. I'm hoping that's not the case but part of me feel like it will be. Going to take it to the shop tomorrow and have them fully check it instead of my driveway mechanic skills.

Does your engine shake like crazy at idle? I have the Car Gauge Pro app but I'm not sure which gauge to look at.

I assume the Hitachi brand is the direct OE replacement?

 

it doesnt shake "like crazy" or anything, but you can clearly tell it idles strange once the car has warmed up

 

if you have torque (pro) you can add gauges of your selection, hold screen to add gauge, select style, then when it brings up what the gauge will read scroll untill you find short term fuel trims for banks 1, and 2. that will tell you which bank, or how both banks are running i.e. rich or lean.

perfect reading at idle warmed up is 0.0.

positive reading indicates lean

negative indicates rich

hope that give you some help in diagnosing. if you figure it out though let us know what it was

oh had to edit this. i believe on car guage pro... the gauges are different.

100 is perfect

+25 lean

-25 rich

same concept though

 

I purchased most of my OEM Nissan parts at courtesyparts.com (dealership of Nissan in Texas) All OEM parts have one year warranty

 

My friend and another mechanic at his shop looked over everything today. Issue may be the MAF. I guess cleaning it with MAF cleaner didn't work. They could only get their hands on a rebuilt MAF and it idled smoothly without P0300 coming back. However, the rebuilt one failed and they're waiting for an OEM to come tomorrow. Hope it's as simple as that.

 

Swapped in OEM MAF, swapped out front and rear O2 sensor and still P0300. Everything else tested ok. Going to use smoke machine and then run a compression test next.

 

Yeah this code is a bummer, I've dealt with it for years and no solution after replacing numerous parts and a engine. There are soo many possibilities with a PO300 that its never ending for some us.

I think there's an air leak somewhere near my intake manifold, close to VIAS Control solenoid that may be causing my problem. I need to do a full leak test.

 

Disassemble VTC solenoids and clean with lots of brake cleaner or w/e. Merely spraying them out still in one piece isn't enough sometimes. Put power to them and make sure it's actuating, then you know it's still working.

It doesn't have to throw the timing over advanced code for the car to misfire.

 

Still at the shop..can't figure it out. Any one heard of "oil burning" spark plugs?

 

As in, the spark plugs themselves causing oil burning? That's what I'm gathering and, if so, then no. There would have to be oil reaching the chamber for oil to burn and present itself on the spark plugs.

 

Also, check that your cat isn't clogged. My P0300 was caused by clogged precats. I spent thousands of dollars and a year and a half resolving it, and changed everything under the sun except the short block and timing chain related parts. It was a nightmare, but testing for clogged cats is very simple assuming you have a vacuum gauge. Let me know if you'd like a run through on how to test it.

 

Yeah ignore that part about oil burning spark plugs lol. So there was nothing left to diagnose or rule out anymore so I finally asked them to do the compression test. Front three are at 100 PSI and the rear three are at 130 PSI.

Not much left to do but drive this car to the ground.

 

Is this engine number three in the last couple weeks that are gone due to the cats?

 

I have headers so the cats are eliminated. Don't think this was cat related.

 

Interesting. Previous owner must have did something very bad.

If you're in the Midwest... I'm interested :O

Edited b/c I can't read.

 

Yeah even though I'm the third owner according to CarFax, not sure what the previous owners did.

And unfortunately I'm not. I'm in NYC

 

It's not hard to swap, though.

 

Hi Guys,
I am also that unfortunate guy with a P0301 code.
I bought a 6 (aftermarket) ignition coils and 6 Bosch spark plugs. Replaced them myself but I have the same symptoms as everyone else.
1. When at idle the engine vibrates crazy, very abnormally.
2. White smoke from the exhaust.

I have cleared the code and re-read multiple times, first it started with P0301,
indicating Cylinder 1. so like some suggested "process or elimination", i swapped the spark plug and coils with cylinder 6, now I am getting P0300.

Now I've read multiples times that aftermarket coils are a bad idea and suggestion are to go with OEM. Is there anyone who did what i am going through and swapped out with OEM's and got successful results.
Someone went as far as suggestion to change the harness- i seriously don't think harness could be the problem.

Please, please some help me. this is my 1st and only daily driving car, all stock with 205K miles on it.. I can't let it die this way.

Any and all suggestion are welcome and appreciated.

Thanks
G10

 

You already posted this same problem. As previously said you need to replace those ignition coil with OEM Genuine Nissan parts or the oem. Aftermarket parts (Rockauto )Hitachi brands. Buy on the classified section of org a used working oem genuine coil. You also need to do the throttle relearn procedure. Swapping of coil is not a good idea because the ecu will trigger multiple errors code and impending error code.

 

G10, try using NGK Platinums and OEM coils. When I used NGK Platinums and aftermarket coils, I still got the P0300 but that ultimately was because of low compression in my engine. So not exactly sure if OEM coils would have made a difference.

Is there oil in the cylinder and spark plug? Perhaps try running a compression test. Or smoke test to see if there are any vacuum leaks.

 

The P0300 is a multiplies Misfire, if you got no other codes such as specific cylinder i.e P0302, P0304 and etc.... then only possibilities are vaccum leak, such as check your intake hose, make sure you don't have any tear or cracks. Otherwise, the last diagnosis would be difficult would be the valves, if they are not being closed seated correctly during the combustion cycle.