97maxy

My 97 Maxima V6 started running rough a few days ago, and now the check engine light went on. I checked it to find a P0306 code.
How should I go about trying to figure out what the cause is and correct it ?

Thank you...

JvG

Miss fire on cylinder # 6. Cause most likely the coil.
move the trade coil with the cylinder next to it. If the problem moves to that cylinder, the coil needs to be replaced.
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aembleton

that code is a cylinder 6 misfire. that is located at the top to the right. It is quite the bugger to get to, you have to take off the EVAP components. The rough engine is most likely a bad ignition coil on top of that spark plug. I would replace it and you might as well replace the spark plugs depending on their age. NGKs are what we use and is a cheap repair.

aembleton

actually 6 is bottom right. piece of cake to remove

The Wizard

iTrader: (43)

and if the problem doesn't move to cylinder 4, it's most likely the injector back on cylinder 6.

97maxy

Thanks for the replies guys...

Just to clarify, the cylinder is in the front row on the right side when facing the engine ?

After swapping the coil with the coil next to it, how would I determine that the problem moved to that cylinder ? I would think I'd just get the same rough idle.
Also, I cleared the code but I remember that the car has to be driven quite a distance before it will give another reading or having the check engine light come back on. So I wouldn't be able to use the code reader to determine if the problem moved to the other cylinder (getting a different code like P0304 instead of the original P0306)

The Wizard

iTrader: (43)

Yes, cylinder 6 is front row, far right side when standing at the front bumper.

Yes, you will have the same rough idle with the coilpack moved. But the idea is that once you clear the codes, the code will change to 0304 instead of being 0306. The CEL should come on rather quickly, within 10 to 20 miles of normal driving.

97maxy

Got it, thanks Wizard.

So far I cleared the code and installed 3 new plugs (2,4,6) and then swapped the coils on 4 and 6. 4 now has the 'bad' coil. I did order the new coil but haven't picked it up yet as I may not need it ?
Since then I drove approx 50 -/+ miles without the CEL coming on. I also checked to see if there were any codes. The meter read zero codes. The only thing I noticed is the engine idles a little rough when stopped at a light (in gear, foot on brake) but seems to be running much better than it was before. 30 mph or more there is no noticeable roughness, it's only noticeable when stopped at a light.

At this point what do you suggest I do ? I was expecting a P0304 but so far nothing but a little roughness. I suppose possibly the new plugs may have helped some what.

Thanks...

The Wizard

iTrader: (43)

How did the old plugs look on cylinders 2, 4 and 6?
What brand were they?
What brand did you install?
New plugs would definitely help lessen the rough idle that you are experiencing.
As for the next step, I would replace the plugs on cylinders 1, 3, and 5 and see if there is any further improvement. And I'd wait to see if 0304 eventually shows up before installing a new coil.

97maxy

The plugs didn't look too bad, they were NGK-R PFR5G. I installed Bosch Double Platinum.
I took the car out the next day and within 5mins the CEL went on (P0304). So I installed the Coil, a Duralast. And so far it seems to be running fine. I cleared the 0304 code and we'll see what happens.

Thank you for your help...

JvG

Our cars prefer NGK plugs.

Should you experience roughness symptoms in the future, buy the NGK.

Glad that your problem went away.

the injesters are harderived to deal with. Especially the ones by the firewall.

97maxy

Thank you, I didn't know that. Should I run into problems down the road, I'll replace them.