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Discussion Starter · #1 ·
Hi all,

Mine is a Murano AWD 2005 at 138K mileage. I recently got a Service Engine Soon light and P0303 (Cylinder 3 misfire) was the code pulled from the OBD scan tool. A bit of history:
  • About 1.5 years ago, I replaced all 2 Camshaft sensors and one crankshaft sensor due to some error code (that I cannot remember).
  • Probably after that (though I am not sure if this could happen before that), the car started shuddering. The symptoms were just like what described in the first 2 posts here (and that happened only when the engine had been warmed up)
  • MPG started to go down from 18-19 MPG to 12-13 MPG (and even lower recently) (mix of city and highway). At some point, the error code for catalyst converter also came up, but later went away.
  • Then a few days ago P0303 came up.

So my questions are:
  • I am thinking of replacing all 6 spark plugs and ignition coil of cylinder 3. Would this be a good start for now?
  • The previous owner seemed to replace all sparks (with a Denso ones, not original NGK Platinum) before I bought the car when it was at 120K miles. Also, 2 (of the 3) spark plugs and coils in the front has oil on them when I pulled up. Should I replace these coils as well, or is this a different problem that I would need to fix?
  • Would these fix help bringing the MPG back to the earlier efficiency?

Thank you all very much!
 

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Hi all,

Mine is a Murano AWD 2005 at 138K mileage. I recently got a Service Engine Soon light and P0303 (Cylinder 3 misfire) was the code pulled from the OBD scan tool. A bit of history:
  • About 1.5 years ago, I replaced all 2 Camshaft sensors and one crankshaft sensor due to some error code (that I cannot remember).
  • Probably after that (though I am not sure if this could happen before that), the car started shuddering. The symptoms were just like what described in the first 2 posts here (and that happened only when the engine had been warmed up)
  • MPG started to go down from 18-19 MPG to 12-13 MPG (and even lower recently) (mix of city and highway). At some point, the error code for catalyst converter also came up, but later went away.
  • Then a few days ago P0303 came up.

So my questions are:
  • I am thinking of replacing all 6 spark plugs and ignition coil of cylinder 3. Would this be a good start for now?
  • The previous owner seemed to replace all sparks (with a Denso ones, not original NGK Platinum) before I bought the car when it was at 120K miles. Also, 2 (of the 3) spark plugs and coils in the front has oil on them when I pulled up. Should I replace these coils as well, or is this a different problem that I would need to fix?
  • Would these fix help bringing the MPG back to the earlier efficiency?

Thank you all very much!
I have no experience (knock wood) with CVT issues so if shudder is from that I cant offer any opinion.

But I can comment on the oil in the spark plugs and the P0303 code. I think for around $225 on Amazon you can address these items:
  • New valve covers $53
  • New NGK plugs 6 at $12
  • New coilpaks at $77 (all 6) I used BraverX at a recommendation of somone on here
  • New gasket set $16

With the above you will have likely addressed the oil in spark plugs and the P0303 code. Maybe the shudder as well?

Good luck

Lance
 

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At 138K miles your plugs are a bit past ready for replacement. IMO coil packs can be left alone until they fail, but others differ. The ones with oil exposure need to be replaced so you're already halfway there, why not do all of them?

But the valve covers come first. They're the fix for the oil leak, which will ruin coil packs.

And if your plugs aren't firing, the popular theory would be yes, fixing this stuff should improve gas mileage. :geek:
 
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Discussion Starter · #4 ·
But I can comment on the oil in the spark plugs and the P0303 code. I think for around $225 on Amazon you can address these items:
  • New valve covers $53
  • New NGK plugs 6 at $12
  • New coilpaks at $77 (all 6) I used BraverX at a recommendation of somone on here
  • New gasket set $16
Thank you! I saw in your other post the replacement of the PreCat. Should I be worried about it as well you think? As I mentioned earlier, my car used to show the error code for the catalyst converter. The code disappeared after a few days, but gas milage has been bad (or worse) since then.

How did the BraveX coilpaks function so far? I know the OEM ones will be much more expensive, but I do not know if I want to re-do everything 6-7 months from now in case the aftermarket ones fail.

At 138K miles your plugs are a bit past ready for replacement. IMO coil packs can be left alone until they fail, but others differ. The ones with oil exposure need to be replaced so you're already halfway there, why not do all of them?
Thanks. But can you clarify a bit? Did you recommend me to replace all coil packs as well? I could not follow "coil packs can be left alone u ntil they fail, but others differ".
 

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I've used a few brands of coils over the years. Denso was definitely the best, but very costly. The last 150,000 miles I've used BraveX, DWVO, Hitachi, and another brand that's been discontinued (the last one produced amazing performance but they would typically fail within a few months). Of the three I mentioned, the Hitachis never failed, but I thought performance was a little lackluster. Two of the BraveX coils failed within six months (the easy bank to do), and BraveX reached out and offered to give me some new ones, but I declined, and instead tried DWVO. Both BraveX and DWVO gave the same performance, and none of the DWVO coils failed after 75,000 miles, and the remaining BraveX coils were still working six months later when I changed them. I'd have no problem using either three again, even with the problem I had with the BraveX.


DWVO
Amazon.com: DWVO Ignition Coils 6-Pack Compatible with Nissan Altima Frontier Maxima Murano Pathfinder Quest Xterra - Infiniti - Suzuki V6 3.5L 4.0L : Automotive
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BraveX
Amazon.com: Bravex Premium Ignition Coils for Nissan Altima Maxima Murano Pathfinder Quest 3.5L C1406 UF349 5C1403 (6 Pack) : Automotive
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Hitachi
Amazon.com: Hitachi IGC0006 Ignition Coil : Automotive
Buy Hitachi IGC0006 Ignition Coil: Coils - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com
 
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Thank you! I saw in your other post the replacement of the PreCat. Should I be worried about it as well you think? As I mentioned earlier, my car used to show the error code for the catalyst converter. The code disappeared after a few days, but gas milage has been bad (or worse) since then.

How did the BraveX coilpaks function so far? I know the OEM ones will be much more expensive, but I do not know if I want to re-do everything 6-7 months from now in case the aftermarket ones fail.


Thanks. But can you clarify a bit? Did you recommend me to replace all coil packs as well? I could not follow "coil packs can be left alone u ntil they fail, but others differ".
My case was similar to yours and after the p0300 code I just decided to spend the $300 or so and do the Precat 1 to take care of the nagging p0420 code and new plugs and coil paks to take care of the po300. Was a gamble that it would solve the issues but I was willing to spend a few hundred dollars to find out. So far I have 600 miles on it and runs great.
I did the work myself. Likely not worth it if done by a dealer. PreCat 1 was$99 on Amazon. My fear was that the Precat was injested into engine and destroyed it. Many articles of such online. In my case appears as though I dodged that bullet. Hoping same for you.
 

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Thanks. But can you clarify a bit? Did you recommend me to replace all coil packs as well? I could not follow "coil packs can be left alone u ntil they fail, but others differ".
Clarification - I don't replace coil packs until they fail. Others disagree and replace them all at intervals or when any unit fails. At 138k miles with three known bad, I'd replace them all.
 
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Did you look up your code on the Internet???

It is missing on cylinder 3. That has nothing to do with the converter. Please don't start guessing, research the information you have.
 

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Discussion Starter · #10 ·
Did you look up your code on the Internet???

It is missing on cylinder 3. That has nothing to do with the converter. Please don't start guessing, research the information you have.
Sorry if I did not explain my question well. I did research about the code and hence my first post.

But because earlier a different code related to the converter (that I cannot remember) came up and went away a few days later, and because now I am hearing that noise and setting that smoke (in the video above) in the exhaust pipe, I wanted to check if it could be another problem, in addition to the cylinder 3 one.
 

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Thanks for the clarification. I suggest you stay with the code you have unless the other one re-appears.

Smoke comes in blue, black or white. Those are oil, gas or coolant respectively. Unless it happens repeatedly I'm not inclined to do more than keep an eye on it.
 
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Sorry if I did not explain my question well. I did research about the code and hence my first post.

But because earlier a different code related to the converter (that I cannot remember) came up and went away a few days later, and because now I am hearing that noise and setting that smoke (in the video above) in the exhaust pipe, I wanted to check if it could be another problem, in addition to the cylinder 3 one.
After watching your video, I have to say it looks and sounds like my 2003 last year when I started having variable valve timing solenoid valve and camshaft position sensor issues, along with what some others have guessed is a timing chain issue or a cracked head or blown head gasket. I think I have a blown head gasket. Your exhaust is blowing smoke rings in that buffeting-like pattern, and mine never did that until things went completely haywire. The car will start and the engine run, but there's virtually no power for the car to move once placed in D. And, once placed in D, the Service Engine Soon light starts flashing at 5-cycle intervals. If cyclinder #3 is misfiring, perhaps that's why you're having issues, and that correcting it may solve your problem. I had three partially dead cylinders and the result is an engine that still started and idled, but when placed under a load it wanted to die. Could have been the angle or distance, but your engine doesn't sound right at all when being revved. How high were the RPMs when you did that, and was the hood open?
 
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Watched the video. Looking at the exhaust smoke, it looks like you have one or two totally non-firing cylinders. The putts and rings coming out is the result of this.

The little bit of white smoke is unburned gas, resulting from stepping on the gas. If you had a cracked head, the white smoke would be so thick that you'd have trouble seeing the back of the car when stepping on the gas.

My suggestion would be to do a complete tuneup, replacing the three back coils with new OEM ones. This way, if you have a bad coil, it will end up in front, where it's easily changed out, and you'll have spares.

Good luck.

Have a good day.

PS As I've stated before, always use OEM, or OEM manufacturers' electrical parts on Nissan automobiles, especially in the engine compartment. Nissan electrical specs are very stringent. Cheap aftermarket electrical controls are the bane of DIY's wanting to save money. Unfortunately, the cheap parts usually end up costing the DIYer more money and aggravation then necessary.
 

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Discussion Starter · #15 ·
Thank you all for the inputs! I opened the manifold today and did not see any problem with the gasket cover. I’ll still put a new one in though. And I’ll replace all 6 coils and spark plugs and hopefully that will solve all the problems.
 

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Hard to say if you have a leaking head gasket. The amount of exhaust smoke doesn't seem all that concerning, but the smoke puffs and sound of the engine suggest there's a firing or timing issue. However, even a small amount of coolant leaking into a cylinder could be causing the misfire, and a DTC indicating a misfire won't specify if it's related to a bad spark plug, igntion coil, leaking head gasket, etc. If you're not having to add coolant, then it's doubtful you have a problem with a head gasket unless it's very minor and perhaps just starting to fail around the area of cylinder #3. If you're not throwing any codes related to VVTs or CPSs, then it's likely those aren't the issue. If you're not hearing strange noises around the timing chain cover, it's likely not related to the timing chain. With regard to a possible fuel injector issue causing #3 to fire poorly, I'm not sure if a failing/stuck one would trigger a code. I know I experienced one sticking injector for about a four hours, and it never triggered a code - it just made the engine run a bit sluggishly and produced some unpleasant tapping/rattling noises.

LIke Pilgrim suggested, do the plugs and coils on bank 1 and go from there. Check and compare the old spark plugs to see if there's drastic difference in appearance in #3 to #1 and #5. When changing out bank 1 coils, it was always my practice to install the new coils on bank 2 and use them for a few days to ensure they worked correctly, Then, I'd take apart bank 1 and install those coils there. You don't want to go to all the work of replacing bank 1 coils only to find out after everything's together that one is actually bad, forcing you to have to take apart everything again.
 
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I opened the manifold today and did not see any problem with the gasket cover. I’ll still put a new one in though. And I’ll replace all 6 coils and spark plugs and hopefully that will solve all the problems.
I'm not trying to speak for everyone, but I believe the possible coolant leak being suggested here is from the head and its gasket, not the intake manifold and its gasket. Removing the intake isn't going to show you the head gasket condition on the far/back side of bank1 unless you used mirrors and very good lighting. And even then the leaking head gasket could be between cylinders instead of along the outside perimeter of the head, making it impossible to see without removing the entire head.
 
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Discussion Starter · #19 ·
I'm not trying to speak for everyone, but I believe the possible coolant leak being suggested here is from the head and its gasket, not the intake manifold and its gasket. Removing the intake isn't going to show you the head gasket condition on the far/back side of bank1 unless you used mirrors and very good lighting. And even then the leaking head gasket could be between cylinders instead of along the outside perimeter of the head, making it impossible to see without removing the entire head.
I must have misunderstood the head gasket term then. I’ll see if I can get a view into those areas. Thanks!

If you suspect a failing head gasket, there are head gasket leak detectors available that might worth trying before throwing money at other parts:

Amazon.com : head gasket leak tester kit
Thank you! Looks like this test kit requires the engine to run in order to take measurements, doesn’t it? If so, I think I’ll complete the valve cover, coils and spark plugs replacement and put everything together and then see how this issue goes. I really hope that will fix everything.
 

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If there's any type of coolant leak in the head and is making its way into the combustion chamber, you'll have a sweet smell to the exhaust. The larger the leak, the heaver the smell will be.

Have a good day.
 
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