Stereodude

My 2002 SE w/ 200,000km's has a rough idle when it's warmed up. It happens when I let the car idle and warm up or when I'm driving it and stop at a light for more than about 10 seconds. It sometimes triggers a P0300 (Multiple cylinder misfire detected). When it's rough idling, I give the car a little gas and it goes away until the idle has settled back down for a few seconds again. This has been going on for a while, but it seem to be occurring more frequently (nearly all the time now). Based on the exhaust note it sounds to me like it's stumbling.

Per the service manual the possible causes are:

• 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

Based on my searches of the forum the most likely cause is the coils... Does that make sense given the scenario I described?

I haven't done anything recently to the car that corresponds to the arrival of the issue. The plugs are pretty recent too.

rroderiques77

iTrader: (45)

Yup. Multiple cylinder misfires w/o isolating which cylinder is actually missing can be a PITA. If I were you, I would start by checking coils and injectors. These would be the most common problems. Have you done any work on it lately? Are the plugs original?

Stereodude

No, I haven't done anything to the engine around the time this showed up. The plugs are less than a year old and are OEM.

What's the best method to check the injectors and coils?

rroderiques77

iTrader: (45)

You will need the correct tools to check spark and injector pulse. If you don't have the proper diagnostic equipment, then you may have to pay someone else to do it.

Gemner

iTrader: (4)

you can try unplugging the front three coils (one at a time) while the car is running to try and pinpoint which cylinder is the problem. Whichever cylinder it makes no difference to disconnect is your culprit. Obviously this will only work for the front three, but if you get lucky and its one of those then nice

Stereodude

If a coil or injector is bad, why does it only manifest itself at slow idle?

Maximamisfire

iTrader: (1)

For the front three, I would rather disconnect the fuel injectors, which are accessible. For the rear three, we have no option but to disconnect the ignition coils.

Rochester

iTrader: (3)

Not wanting to make you any more glum than you are, but if your dealership can't isolate which cylinder is misfiring, they will suggest replacing all the coil packs. At a dealership cost of (approximately) $110 US, plus labor to remove the intake plenum, that adds up real fast.

I had an original coil fail 18 months ago, and one just yesterday. Both times I was lucky with the misfire code registering the errant cylinder, and both times it was in the easily accessible 2-4-6 bank. My odds are getting worse for the next one.

Maybe you should seek a good deal on a full set of coils now, before you can't drive your car anymore.

rroderiques77

iTrader: (45)

Because it is a random misfire. No isolation of a bad coil.

If money is an issue, do what Gemner said and pull out one at a time. If you're lucky, the bad one will be in the front. Removing the plenum isn't all that hard either. Do you have a socket set?

Stereodude

Money isn't an issue, however I generally do my own car repair rather than making the local stealership rich.

Yes, I have a socket wrench. I've taken off the upper intake plenum more than once.

Stereodude

The stealership will be the last place I go. I will keep a close eye on the codes. This has been going on for months and months and I've just been ignoring it so I think I've got at least a little time to figure it out now that I'm motivated to do something about it.

Rochester

iTrader: (3)

Not all dealership service departments are predatory.

You've been driving your car while misfiring for "months and months"? That doesn't make any sense.

rroderiques77

iTrader: (45)

Well good. Hop to it and start checking those coils. Sholdn't be a problem for you then

sontakke

If the rough idle is consistent, it should not be too difficult to disable one cylinder at a time either by removing the coil connector or the injector connector. If the idle does not become even worse, you have identified the offending cylinder.

I am surprised that it is not tripping P1320. Mine does every month and only once I was able to grab P0305 code. This is the back middle coil and I have been lazy to get to it. HOWEVER, mine never idles or runs rough, so I have let it slide.

- Vikas

Stereodude

Not all dealer are Nissan dealers too. What's your point?
No, I've been driving a car that has a rough idle for months. It will very rarely throw a code. I drive a car that has a problem with the rings and burns oil too, I'm not about to fix that either. If I want to ignore the rough idle what's the big deal?

Rochester

iTrader: (3)

My point is that not all mechanics operate on a business model where the customer is there to be taken advantage of.

Whatever it is you're saying, stick with that if it's working for you.

People offered advice about ignition coils. My advice was to seek out a good deal on coils before your ride becomes undriveable, even though you already said "money isn't an issue." But if money isn't an issue, then just get your car fixed.

And you're defending a choice to ignore the rough idle in the same thread that you're asking for help with your rough idle. Not sure you can have it both ways, champ... but in that theme, good luck not fixing the problems you're complaining about.

It must be frustrating living the paradox. I'm sure it isn't boring!

rroderiques77

iTrader: (45)

Stereodude

I chose to ignore it in the past, now I'm interested to get it fixed. There's this thing called time and things change as it passes.

Stereodude

I should add that I cleared the code and it hasn't come back. I did some more searching of the .org, and right now I'm leaning toward the MAF based on the fact that the idle is dropping from the normal ~700RPM to ~500RPM when it gets rough. Quite a few people solved their rough & slow idle issue with MAF replacement instead of injectors or coils.

max ride 41

iTrader: (4)

bumping 8 y/o thread for a reason, i recently went through a similar situation and decided it's time to do an maf cleanout and/or possible replacement. have sputtering idle at park and stoplights and will probably do a tps replacement if that doesn't work. if it doesn't, i may have no hair left from frustration/ripping it out.

QueensMAX

I once had this problem. Tried everything possible. Last thing I tried replacing was the fuel pump and that was the solution.