Got a 2002 Maxima six speed for my daily driver. Today on the way back from a mountain getaway, climbing a curve, it started missing badly. The missing was proportional to the load on the engine. Series of blinking CELs and solid CELs and sometimes it would go off. It's on solid now, went to Autozone and pulled the codes - the dreaded P0300 - catch me if you can code. *No* other codes pulled.

I should point out the the car has stumbled for some time in low RPMs but no CEL. I replaced the left side plugs, and things were better. I stopped being lazy, replaced the right side plugs (removing UIM, etc), and things seemed much better. Still a little stumble in the low end but much less.

Okay, so I've been reading a lot here. So, the first thing I did was focus on low hanging fruit. Pulled the MAF, cleaned it, reinserted. Seemed to run better, but she's still not there. I can feel the missing. I can see it on the tach. Based on other posts, I do not think it's an ignition coil, but I might check that later. Thoughts?

So, she has 150K on her, and I expect stuff to break, no issues there. Went through the MAF area looking for broken hoses, etc. Came across a hose that runs toward the back of the engine - no clue. See pictures. I can find no place to connect this hose too. Ideas?

Finally, let's talk about valve covers and the infamous attempt by Nissan to f*** up a wonderful engine. When I swapped out the plugs, the left side was fine, no oil in the plug wells. The right side had the one area that some oil had collected - nothing terrible, but I cleaned it up. So, regarding this area:

- does the oil that seeps into the right side plug wells affect the spark plug boots or anything at all? In other words - is this just cosmetic?
- reading other posts, I'd like to replace the right valve cover. do I just order one for a 2004? Can't see any reason why I would replace the left valve cover as it's fine. For the right side, I can order from amazon, ebay, online Nissan dealers, etc. Does it really matter?
- at 150k things made of rubber tend to fail. I have six spark plug boots/wires plus coils. Does it make sense to go ahead and swap these out? How could I test to justify this expense?

Appreciate any feedback.

 

Oil on the plugs can cause a misfire. Spark will short.

You don't replace coils unless they're bad b/c it is a huge waste of money (also what junkyards are for).

I would start with ganking a couple coils and maf (might as well while you're there) from the junkyard. If it misses enough to diagnose which cylinder it is by unplugging, then there ya go. Otherwise, I would try swapping one coil at a time with a replacement and see if you can get it to abate. It's pretty uncommon to be an injector. Can try maf swap anytime to see if any change.

 

the hose is your transmission breather hose, it doesn't connect to anything

 

cornholio! ty so much!!

 

P0300 is usually caused by a problem common to all cylinders, such as:
- Intake leak,
- Fuel delivery problems, poor fuel pressure, bad injectors, etc.
- Bad primary O2 sensor,
- Clogged pre-cats.
As you may know, the last problem is quite common on our cars, after 14+ years and 150+k miles of use. You said that your missing is proportional to the load on the engine .... perhaps your pre-cats are not letting the engine breath?

 

He said after replacing stuff...idk.
Maybe he needs to clarify the exact symptoms, now.

Is it an individual cylinder type miss or are all cylinders judt kinda going bleh. Does remind me of intake leak and there's been a rash of crackee intake boots lol

 

I would check compression first before spending money on parts. I spent tons of time and $ chasing a p0300 and when I finally checked compression found out the motor was shot. Low compression in 1 3 5. So please do that and it doesn't cost anything to boot

 

Responding to Child, the only thing I replaced were the plugs. Sometimes it's useful to let people know what you've done lately (might be that that introduced the issue). I don't think it did as (a) noticable improvement with new plugs and (b) had there been a vacuum issue from my work, I would think it would have shown up immediately.

-------

I'm nursing it along for now. I'll see if I can run a compression check tonight. Never done it, so it will be entertaining. Might pick up a boot / coil just to check things out.

Any thoughts on the valve cover? To resolve the leaking cylinder well issue, just buy the 2004 Maxima cover?

Last question - in shopping for MAF sensors, I'm shocked at the price differentials. What is so special about the Hitachi at $150 (oem likely) as compared to a $30 version? I think I'll swap that out just for cheap thrills.

 

I just grabbed a cheap 18$ MAF on eBay, just to see if that was the culprit, before I dropped 100+$ on an oem one, and I'm going to agree with precats also, could try gutting them, might solve issue as well.

 

Yeah well, today she ran fine on the way into work. Only missed a couple of times and when running smooth, pulled just fine. I'll search the site for something that tells me how to remove the pre-cats (punch them out). For now, I'm going to avoid panic operations and fix what I know is bad and work from there. I picked up a MAF sensor off ebay as well.... should be here tomorrow.

 

I also had the occasional 0300 but after hitting 100k+ I had my mechanic use the 2004 valve covers - he wasn't happy - he normally works on 3XX's but I trust him and he did what I asked. I have not had another 300 in the last 20k. Thought this might help.

 

Does the oil on the end of the plug appear slimy black as opposed to just dusty black? He may be able to tell by just the appearance.

 

You can easily test the coils with a volt meter.

Touch the meter to the plug side then to the pins check for impedance/open circuit. If the plugs don't appear slimy and the circuits/coil packs check OK your fine.

There is no reason to swap junked sensors for diagnostics.

Radio Shack has cheap volt meters but if you want to test the O2 you may need one that tests milli-volts but you should be fine with a regular one.

 

I'm not sure why maximatech12 is giving bad advice like this He's quickly developing a reputation for wasting peoples time.

A weak or intermittent coil will often test fine but have issues under load. If the coil is completely shot it'll be relatively easy to find out which one it is without a test.

As others have said. sometimes it's best to swap in one or more known good coils and drive it till you find a combination that fixes it or you rule them out.

Saying "you're OK" if they pass the test is very misleading. This is the type of advice that has people leaving bad parts in their car and chasing in other directions.

 

Patients just contact Delphi, or Hitachi, or some type of aftermarket ignition manufacturer and request the impedance range.
If the number falls within the range your fine.
Again There is no reason to swap out these coil packs. There is a way to test them you just have to ask the right people.

 

Check EC-516 in the Nissan service manual.

Box 16 gives you a way to cancel out the power transistor as the issue.

It just illustrates probing the 2 and 3 terminal on the transistor for resistance. If there is resistance replace it if there is no resistance it's OK.

(2001 FSM)

 

 

That's good information if you have a stone cold dead coil. And if you have a stone cold dead coil, you don't need to waste your time with the ohmmeter as a dead coil is very obvious. It is rare for a coil to totally die on you, the transistor weakens and becomes intermittent, yet still may give an acceptable ohm reading.

 

Can you define the word "intermittent" so there can't be any confusion to it's meaning!

 

Quoting the shop manual is a poor substitute for experience. Have you actually done any of the things you're recommending here? Have you successfully diagnosed and fixed a car? Why are you even wasting peoples time here when you know nothing about the topic? It's not the least bit helpful so what are you getting out of this?

 

The P0300 code got my *** a couple times..Worst one to figure out...I had one car that really gave me trouble. Found out it was the sluggish fuel pump was causing the random misfire.

 

Since the 01 max has no fuel pump testing terminal you just test pins 1 & 3 on the fuel pump/fuel level sensor terminals. If you have the 2002 max it maybe slightly different.

should be between .2 - 5 ohms. If not it's bad replace it.

Check out the section in the Nissan FSM on intermittent issues it's usually a bad harness connection due to corrosion.

fuel pressure test/fuel injector probing and again harness inspection.

always test for open and short circuits

 

Well, i've been busy working on the Max, so I've fallen behind. What I did today was to remove the upper intake manifold and replace the rear valve cover. It's been leaking - I can smell it, and I know when I changed the plugs it was leaking in the rear.

I took this time to examine the boots and plugs. One was somewhat gunky - #5 - so I cleaned it up and proceeded to replace gasket and rear valve cover. Toss in two trips to the store for a torque wrench (I wanted to do this right), and a wayward wire, it's all back together and running. We'll see if I got that #$%$^% leak. Car has a little more than 150K on it. All I need is to get to 200K and I'll donate it.

Misfire - so after I fired the car up, I started pulling ignition coil connectors. Starting with the front, I pulled #6, stumble, lower RPM, okay it's good. Pulled #4 - no change at all. Hmmmm. Pulled #2, stumble again.

So, I'll swap out the #4 coil with a new one - and report results.

Note: ALL of my coils have the gray dot.

Appreciate all of the ideas and suggestions.

 

If you get the Car Gauge Pro app for Android you can connect to the ECU and shut down individual cylinders from your phone.

 

Okay, *that* sounds like a cool app Will need to check it out. I was glancing through the FSM looking for things, and I came across a reference to a CAN-Bus. I work in embedded s/w development, and we've used this in past projects. The description was intriguing - about how they use it as a network to communicate across all of the processors in the car.

Thanks for the pointer.

 

There's also the "Torque" app. It doesn't let you make changes but it lets you create dashboards with a gauge for nearly every sensor on your car. You can view the info as a chart as well with different sensors. It's pretty slick.

Car Gauge Pro gives dashboards and gauges as well but it's not as slick. I keep it for the adjustments it can make. Both of them double as code readers and can clear codes.

 

Gentlemen - I appreciate all of the suggestions and ideas.


The culprit was the #4 cylinder ignition coil. Going to pick up a few used ones off ebay - $13 / each. That way, I'll have a few spares. Went to AutoZone and for $71 there's no more stumble or miss. I guess the coil has been slowly deteriorating.

Thankfully, it was on the left side of the engine , although I think I might be able to get my fingers under the upper intake manifold to reach cylinders 1-3-5. It's an easy check for P0300. Certainly look at cleaning the MAF and testing these things before hysterical efforts are attempted in other areas.

Now that damn manual reset of the SES light is aggravating me.

 

Good deal. Glad you got it worked out.

Forget the manual reset. Get the phone app or just have your local auto parts store clear it. It'll go away after a few drive cycles too.

 

So the coils can get old and weak?
I would've thought it could've been a pressure regulator?
I got a slight missing at idle intermittently. If I change all the coils will it go away?
The car kind pf sputters a bit at idle when I rev engine then let off of the throttle completely. I have no codes at all accept a P0420 that I clear off. I replaced all fuel injectors and plugs. With OEM pRts NGK/HitAchi

 

Yes, coils do get weak. Each coil has a transistor in it and transistors do wear out.

I don't think that your sputtering problem is a coil problem. I'm thinking fuel related. The P0420 could be your bank 1 pre-cat plugging up.