I just got the P0300 code. Background: Coils and plugs were replaced 2yrs/20k miles ago. (I used the BWD coils because they have a lifetime warranty- I know, not OEM) I searched and found some info on coil resistance checks and found some inconsistancies...

Forum post:
POS to 1 and NEG to 2 -- should show infinite resistance
POS to 2 and NEG to 1 -- should show continuity but not zero ohms.
Connector number 3 is a trigger and is not measurable.

Connector:
___|--|___
| 3 | 2| 1 |
------------
FSM:
POS to 2 and NEG to 3 -- should show not 0 ohms, if 0 ohms replace
(page 717 of 766, section EC of FSM)

Connector:
___|--|___
|1 | 2| 3 |
-------------
SO...I followed the FSM and tested all but cyl. #1 since i cant get to it. All measurements come back around 6 MegOhm. This is far from 0 and they are consistent so I assume its not the coil packs. Plugs on cyl. 2-4-6 look good, cant get to back ones.


In the trouble shooting section of the FSM, section EC for code P0300 it gives the MAF as a possible check... The MAF is original, car has 145k on it. Could this be my problem? What do you think about my ohm readings? Nissan dealer says to replace the coils, the car runs rough when loaded mostly, but sometimes at idle also.

 

Aftermarket coils aside from Hitachi are known to cause issues.. I tried various aftermarket myself and all brands ended up screwing up very quickly

 

Thanks, I know it's possible. What do you think of the resistance checks?

 

Not much. The coil contains a transistor circuit, and it's very hard to evaluate how it works by only measuring the resistance (but the resistance looks strange/wrong to me). The following two threads (and the first one in particular) will tell you how to diagnose your problem:
https://maxima.org/forums/5th-genera...help-asap.html
https://maxima.org/forums/5th-genera...e-misfire.html

P0300 indicates multiple cylinder misfire. My guess is that you have bad coils, or perhaps a vacuum leak, or both. At any rate, follow the instructions in the first thread to diagnose your problem.

If you decide to replace your coils, buy only Hitachi/OEM. Rockauto sells them at a very decent price.

 

Thanks for your help, I'll get to it this AM and get back with results.

 

So I replaced the easy coils since my tests were inconclusive. 1-3-5-6. Still has the same problem with stumbling/shudder. I cleared code p0300 and it hasn't come back even though the problem is still there, only drove it a few miles though. Should I go through the work to change 2-4 coils? Or get into the maf?

 

What about a intake air leak. What's the best way to check that?

 

Check out this video

 

You may have to broaden your search. I assume you have a copy of the FSM (if not, get it from here: http://www.nicoclub.com/FSM/Maxima/2002/ ). For P0300, the FSM lists the following possible causes:
- Improper spark plug
- Insufficient compression
- Incorrect fuel pressure
- The injector circuit is open or shorted
- Injectors
- Intake air leak
- The ignition secondary circuit is open or shorted
- Lack of fuel
- Drive plate or flywheel
- Heated oxygen sensor 1
- Incorrect PCV hose connection

When is the last time you cleaned your injectors?

 

Ok so I did the intake check with carb cleaner. Nothing. I will continue to drive and hope it throws another code. Thanks for the help and yes I have the FSM. I have been looking over that section you quoted from. Looks like i'm in for some fun.

 

It finally threw a P0301. So i ripped apart the intake and changed all my packs. Now it runs good! Thanks for your ideas and help!