So I went to Auto Zone to have some codes run since my check engine light goes on and off and the code reads P0300 / Random Multiple Misfire Detected.

I put new NGK spark plugs put in but that didn't make my check engine light go away. I heard that most of the time the problem is the ignition coil and one of the ways to test it is with a ohm meter. I don't have an ohm meter, is there any other legit ways of testing coils.

 

yes. Unplug each coil one at a time when the engine is IDLING. The coil that causes NO CHANGE in engine idle is the bad one.

an unplugged coil should cause the engine to stumble.

The above test is not a sure-fire way, as sometimes the coils can test good (even with an ohm-meter, mind you) and fail under load.

 

Coils are not the only possibility with the P0300. Check the FSM for possible solutions, as there are many.

 

So what do I do if the front 3 seem to be working fine? How do i check the rear since I will have to dissemble the manifold.

 

Also is it ok to take a coil out while the engine is running, for testing? or should I take it out then start the engine to see if its feeling rougher.

I just don't wanna damage anything.

 

Pretty sure it's ok to just unplug the connector while it's running.

I had this code a long time ago, and unfortunately there are a ton of possibilities. Mine was a vaccum leak at the six port spacer between the upper and lower intake manifold, when I installed them I over torqued the front three bolts which caused the leak. Your sig doesnt say anything about spacers, but if you just had the UIM off to change the plugs make sure you didn't do the same, they take very little torque (I think about 12-15 ft/lbs).

It also applies to the rest of your intake, between the maf sensor and motor, if there is a vaccum leak anywhere it could cause this code.

 

+1
I got a code and found a leaky hose on the PCV. Check your FSM and you will see. Its not always the coils.

 

Thanks for the reply's,

I'll check a service manual and work from there.. Hopefully its easier than expected. If not then I guess I'll have to fork out the $90 and have it tested in shop.

 

Tested all the coils and they are still working, my check engine light is now off which is strange. I didn't disconnect the battery or reset any codes. Maybe one of the ignition coil connector's was loose when I was testing. I guess well see if the check engine light comes back on in a few more days.

 

i you are getting a random/multiple cylinder misfire code but no supporting codes like p0301, p0302 etc, then most likely it is NOT your coil or spark plug or a specific injector. Instead, it would most likely be something that is associated with ALL cylinders like a intake manifold leak, mass air flow sensor, ecu, ground problem, etc.

More info here: FSM for 2002 maxima, Check out page 317.

 

Thanks man, I will look into checking those problems.

 

My repair manual says that checking and replacment for the MAF sensor does not cover 2000 and later models. These later models are equiped with an updated engine managment system. because of the complexity of the system, have the vehicle tested by a dealer.

Is this true or is there a way to test it? any help greatly appreciated.

 

The P0300 code still comes and goes and I have minimal amount of shake at idle. The car seems to be running good as always, I just can't figure out what to do now?

I have recently replaced the PCV and hose. The Spark plugs 2 years ago with the rear valve cover assembly and new manifold gasket. I did have oil sitting on top of the spark plug in one of the rear cylinders, so that was the reason for replacing the rear valve cover. I'm not sure if the oil still remains since I have not takin the manifold off for two years.

Any next suggestions for problem solving would help alot. thanks

 

I have been wrestling this problem for several months now. The cause of mine is a clogged pre-cat. However, there are a ton of different things it could be. If I may, I would recommend reading through my thread, as I did a lot of testing (and replacing) that might help you out.

http://forums.maxima.org/5th-generat...kets-help.html

-Nathan

 

On my 2K I eventually replaced all the coils over 12 years and only half of them were causing ECU to give supporting code with cylinder number. Most of them were intermittent- one day it works, another - doesn't then comes back again and so on. One was particular bad, I was hunting for it for few weeks as it was creatively failing at the times when I couldn't pull off and start disconnecting connectors. Eventually this one was also identified. It helps if you keep your hand on some part of the engine to feel engine stumbling better. BTW, don't remove the coils, disconnecting connectors is much better as you can connect/disconnect it on running engine and feel the difference.

 

I ran across that this week, P0300 error code and blinking CEL. By unplugging each coil I found the bank 4 to be the problem. Here is the result:



I replaced a coil with the one that I had sitting around with a brand new NGK Iridium plug. No more rough idle, no more missing, she is running pretty smooth!

 

About a month ago I was getting P0304. I replaced all spark plugs but the light didn't go off. I then replaced the cylinder 4 coil and the light went away. Then last week I started to feel the rough idle again. This time I got a P0303 code. It lasted two days but went away by itself. Now I still feel a rough idle occasionally and have a pending P0300. Not sure whether I should just replace the cylinder three coil or do something else. Very frustrating to read it could be many things that are wrong as I'm not a gear head.

 

With the P0303 code I'm getting, I'll have all three rear coils replaced. Spark plugs were replaced recently. While I have it in the shop, should I change anything besides the rear coils? Something that could be causing the P0303. I don't want to just replace the coils and find out something else needs to be looked at or changed for that cylinder.

 

Maybe clean the fuel injectors while your back there..

 

In reference to P0300 if ur taking the manifold off u should replace the lower intake manifold gasket and the upper intake manifold gasket and why not try the elbow manifold gasket aswell and the throttle body gasket is accesible too

 

Thanks, I was looking at replacing the gaskets as well. I've been getting P0300, P03003 and P03005 for the past month now. Each time the light will come on for a day or so then go away.

 

Please help guys,
I have ran into a problem from changing the valve cover gaskets on my 2002 maxima se which i also just bought from a guy with 140k on it. The service engine light came on after i reassembled everything. The codes show that its having multiple cylinder misfire mainly i think but also codes
p1448(Evap canister vent control valve)
p1800(VIAS Control Solenoid Valve Circuit Open because i took out the valve for the vias delete which probably sucks anyway)
p0507(idle speed control system)
p0455(evaporative emissions system large leak( I think from leaving gas cap off once i think...))
The car is driving unbelievibly sluggish, its putts from the exhaust, engine seems to shake more at idle and when giving gas to it. I only babied it to get the codes checked about 3 miles. So can any one tell me what might have gone wrong and what i need to correct? I know i tightened the intake manifold bolts down too much so will i need to replace the gasket again i think right? I also found that one of the coils was bad and oil was getting into the spark plug tube so i replaced the coil and plug which are both different from the others now. Please help I need to fix this.. don't have funds to bring to shop. Thanks.

 

Alright man, if you didn't have all those codes before you did the vcg's, then I would take a good look and make sure you hooked everything back up correctly. All vaccum lines and everything.

As far as over torquing the manifold, the gasket should be fine, hopefully you didn't strip the bolt holes on the LIM. Just get a torque wrench and tighten them to about 12-15 ft/lbs using very careful judgement. Aluminum is very soft.

You might need to do an idle relearn, so look that up and perform that. It can be a bit tricky so it might take a few tries.

When I did my IM spacers I forgot a couple of the vaccum lines between the manifold and firewall, and the fuel line to the fuel rail was twisted and kinked. With a fresh set of patients, go back, look over everything you touched and take your time. You'll figure it out.

 

all right I got p0300 on my car, before that i had p0301 and pending code p1320. I swapped coil from cyl1 to cyl3 and see if coils fault but then got p0300. While its running, I unplugged each coils and see if anything fault but none of them. Spark Plugs are brand new. Unplugged 3 front fuel injectors and they are good. Air filter is new. All the hoses are good.

I was re-assembly rear valve cover for gasket and everything is hooked up. Cleaned egr. Could it be IVAC? EGR vacuum modulator valve? Could it be coils are very weak? Am I missing something while i put rear valve cover back together?

 

With P0300, it's probably something associated with all cylinders like an intake manifold leak or bad MAF or bad ground somewhere. Get the FSM for your car (from here http://boredmder.com/FSMs/Nissan/Maxima/2002/ ) and follow the suggestions there.

 

Ok I found hose is cracked. I ordered this part from OEM, hopefully its fixed.


Other thing this hose from behind of UIM is little tight. its normal?

 

Glad my suggestion helped. Check all other hoses as well. By the way, which hose did you find the crack on? - it's hard to tell from the picture.

Not sure what you mean by "tight"; do you feel that the flow through the hose may be constrained? If so, remove it and check it out.

 

its the hose between front and rear valve covers

 

I wish that's all that it was in my car

 

Hey again, replaced new hose and still getting misfire. I was hoping that hose fix it but its not . I did compression test this morning and cyl1 has 165psi and the rest have 175-180psi. Cyl1 has lowest psi of all and FSM said 146-180psi are ok. So cyl1 should be ok.

When I change gear to R or D with no load, its getting more misfires than idle. When I drive, its not getting misfires. I can't find anything with this situation... What do you think of this? Could it be EGR?

Also I found 1/4" inches of hole from exhaust and its leaking. Its between after o2 and before flex pipe. But I dont think its causing misfire.

So far spark plugs, fuel injectors, coils are good. All hoses are hooked up and no damages and no leaks.

You have any other suggests for me to look for?

 

Might be worth it to do a smoke test for any other vaccume leaks. How are your precats looking ?

Your compression should be fine. After the smoke test if nothing is revealed it might be worth it to do a leak down test.

 

Precat looks good no damages. Where can I find smoke test and which hose should I put it in?

 

Use the brake booster line. Watch a how to on YouTube