01 Ignition Coils, parts question

[IncidentalOffroader]

Hello all,

 

My 01 Pathfinder with the VQ35DE engine is acting like it wants new ignition coils. Apparently coil failure with this engine a known common problem, most recently discussed here at http://www.nissanpathfinders.net/forum/index.php?showtopic=8879, and several other places in this forum and others.

 

I plan to buy the #2-#6 coils and replace them myself (the #1 coil was replaced at the dealer shop about 2 years ago). My question is, are the new ignition coils being sold a different, more reliable design than the old ones? Or should we resign ourselves to replacing them every few years? Does Nissan have a new part number for the new coils? Is there a way to know if the coils I buy are the new ones?

 

I noticed at some on-line parts retailers, there are 2 choices for 2001 ignition coils: those for Pathfinders manufactured prior to 8/2000, and those after. My date code is 5/2000 so it seems obvious which part to get. But I want to make sure the post-8/2000 coils aren't the new-design coils I should get if I don't want to replace all the coils again in a few years.

 

Thanks,

Mike

[BowTied]

Did you already check your plugs' gaps?

[bigmatt]

Did you already check your plugs' gaps?

 

I second this, I would say replace your plugs first. It took me about 3 hours to do and it gives you a good chance to inspect the coil packs. If they are the original plugs, chances are they are worn out of spec. Just make sure to use anti-sieze on everything and also put a good amount of dielectric grease in the blug boot before you re-install it.

 

Just out of curiosity, did the dealer replace any of the plugs when they replaced coil pack 1? I wonder if the dealers aren't replacing an expensive coil pack instead of cheap plugs just because that's what some computer is telling them to do.

 

Bigmatt

[IncidentalOffroader]

Too late, I've already ordered the new coils!

 

I have about 50k miles on the original spark plugs... aren't they supposed to last, like, another 25k? Should I just go ahead and replace them since I'll already be there when I replace the coils?

 

I can't say for sure if the dealer looked at the plugs when they prescribed the #1 coil replacement. They certainly did not recommend new plugs, or mention them as possible culprits. If I had to guess, they probably didn't look at them, considering the miles on the car, and the known ignition coil reliability problem.

 

-Mike

[BowTied]

Too late, I've already ordered the new coils!

 

I have about 50k miles on the original spark plugs... aren't they supposed to last, like, another 25k? Should I just go ahead and replace them since I'll already be there when I replace the coils?

-Mike

 

 

Ok, I have not (yet?) had the coil issue. I changed my plugs while I had the top end apart for applying loc-tite to the power valve screws to avoid that problem. FWIW, my plugs looked fine and were only .001 over gap spec which could be the allowable tolerance or perhaps my measuring technique. (111,000km). But I figured "While I had it this far apart"... if you are going to replace the coils anyway, why not? Even if the plugs are good, it is relatively cheap peace of mind. PLUS If the plugs are bad (way out of spec) they could actually burn out you new coils after a while. The larger the gap the higher the voltage required to make the spark jump that gap. So, you will have it that far apart, and the plugs will be at least out for inspection.... well it is up to you of course.

 

If you have the time, it would be a neat experiement to replace only the plugs and drive it for a day to see if that helped.

 

JMO.

 

BTW, is this a 2001 problem only or does it affect all 01-04?

Edited February 12, 2008 by BowTied

[IncidentalOffroader]

I agree inspecting the plugs while I'm replacing the coils makes sense.

 

Another reason I think the coils are the culprits is that the problems are very intermittent. The first time this happened about 2 years ago, the engine ran very rough at idle (like it was totally lopsided), had no power, and the SES light was blinking (which I interpreted to mean misfiring). I stopped and poked around to see if there wasn't a fallen-off hose or connector, and after 30 minutes started it up again and everything was fine. A few days and about 300 miles later everything was still fine, but I took it to the dealership anyways. Basically they charged me an hour's labor to clear the code and tell me whatever was going wrong wasn't happening anymore, so there was nothing to fix (it was then I resolved to get myself a code reader). About a month later the SES light came on again (though not blinking, and there was no evidence of misfiring), and this time the dealer said the codes indicated a misfiring on cylinder#1. They recommended replacing all 6 coils because of the known coil reliability problem. I only had them replace #1.

 

About one month ago the engine started showing those same unmistakable signs of misfiring. And again, the problem cleared up overnight. I checked the DTC codes myself this time (now that I have a code reader): P0158 (O2 sensor bank2, sensor2) was logged, and P0306 (#6 cylinder misfire detected) and P1320 (ignition signal) were pending. I cleared the codes and no problem has been seen since (although less than 100 miles have been driven).

 

(The P0158 code has been coming up for a while. I've been ignoring it since I understand it's not involved in engine management.)

 

Because of the widely intermittent nature of the problem, I'm being conservative in deciding to replace the coils. I guess it could just be the plugs, but this happens so infrequently that it'll be a long time before I'll be confident that they were the problem, and the coils weren't the real culprits. The Pathfinder seldom gets driven these days, and whenever we do it's usually on a long road trip, sometimes to remote areas. So I'm less inclined to just change the plugs and see if that fixes it.

 

I'm still trying to figure out the part number question of my original post. Can anyone verify that the part numbers for the updated coils has changed? And if so, what are the new part numbers? I'd hate to ave gone through all the trouble and expense if my engine already has the updated coils, or I end up putting in the old-style coils.

[IncidentalOffroader]

Here is the short answer to my original question on ignition coil parts:

 

- The re-designed coils have the same part numbers as the original coils.

- You can tell a re-designed coil from an original by the presence of a black dot sticker affixed in a conspicuous location on the coil body. See the photo below.

 

If this is all you need to know, you can stop reading now. If you are so inclined, you can read the (long) story of how I came to this conclusion, which begins after the photo.

 

 

 

About two years ago I had the #1 coil replaced by the dealership after it began misfiring. The dealer alerted me to the TSB regarding the coils on this engine, and recommended replacing all 6 coils. I opted to change just the one that was failing. Out of habit, I requested the old #1 coil back and kept it, which was lucky because it becomes important later in the story.

 

A couple months ago, the #6 cylinder began misfiring, so I decided to go ahead and replace the other 5 coils. I intended to order the parts at the best price and install them myself. This is where my questions began. When the #1 coil was replaced, I could be reasonably confident that the dealer would replace the coil with a proper one of the new design. But since I was going to buy the parts myself, I didn't know how to order re-designed coils specifically. I assumed the part numbers would be different, so I started asking about old and new part numbers. But no one could give me any specifics. They could only tell me the PNs of the parts they had available, and could only assume they were the re-designed parts.

 

I then spoke to Dave Burnette of South Point Nissan in Austin, Texas. He's known among the Maxima forums to be very helpful and well-priced. He couldn't tell me the old part numbers, but assured me that I wouldn't be getting original-design coils from him, since it had been many years since the re-design. So I bought my #2 thru #5 coils from him.

 

I pulled out my 5 old coils and compared them with the new ones. The part numbers are molded into the coil body, along with the manufacturer name (Hanshin) and another number. (see the photo below) Between old and new, all the numbers were the same except for a number stamped in white ink (date code? lot number?). I looked long and hard and could find absolutely no difference between the parts. I looked for subtle shape differences, different materials, and marks from the injection molding process, but everything was exactly the same. Except there was a black dot sticker on the all the new parts. Initially I thought the sticker was a hole in the coil body that gets filled with epoxy as part of the manufacturing process. If this were true, I would have been satisfied that the old and new coils were sufficiently different. But I when nicked the black circle with my fingernail and saw it was just a sticker, the doubts came back. The black sticker could mean anything, could have been put on by the South Point Nissan for, say, inventory control purposes.

 

 

At this point I was in a quandry. My old coils appeared to be the same as the new ones. If I assumed that South Point Nissan sent me re-designed coils, it could mean my engine already had the re-designed parts and my misfiring problems were not due to the coils. Should I return the new coils? Should do more research and see if the white inked date/lot number could be used to indicate a redesigned coil? Should I continue and install the new ones despite my doubts, just to be safe, save time, and get on with the rest of life?

 

This is where my old #1 coil came in handy. I dug it out and looked at it... no black dot. Then I looked at the new #1 coil replaced two years ago... black dot... same as the other black dots on the new coils... in a place that's easy to see even when the coil is installed. (See photo below.) Now I was convinced that the black dot meant a re-designed part. The old and new #1 coils also had matching numbers, and the new one had a black dot. It came from a dealership half-a-continent away from South Point Nissan and two years ago, so it's likely that the dots were put there during manufacture. All this evidence supported the theory that Nissan marks the redesigned coils with black dots. I concluded that I had original coils that needed changing, and all the new coils I bought were of the new design.

 

 

A few days later I discussed this with Dave Burnette. I explained that the old and new parts matched exactly, and the possibility that my old coils might have already been the re-designed part. He said Nissan doesn't necessarily change the part numbers, but will mark redesigned parts with some kind of dot. I didn't make any mentioned about the dots before he told me this, so he wasn't merely continuing my line of conjecture. He even shared more corroborating information: in the Maxima's case the coils have been redesigned multiple times, and the newer parts have multiple dots and colors.

 

So after all this, I'm satisfied that I needed new coils and got redesigned ones. So far the engine's been running fine! Hope someone else finds this info useful.

[PDCCD]

WOW, you are one thorough SOB! I love you for it. I imagine this will be an issue for me in the near future, so for your effort and time, I thank you pre-eminently.

[BowTied]

Great follow up!

 

From an engineering persepctive, when changing the design of a part you can keep the same part number if the new part has the same fit, form, and function. Any of those change, then a new part number is required. This keeps things straight when making parts for service and new production and ensures replacement parts will fit. So, the coil with the dot indicates a major revision change of that orignial part number. Since it works in the same way and fits in the same way, the original part number is retained and the dot is a quick identifier for those aware of the TSB, which I bet will indicate the dot is the difference.

[Tbsbiker2]

I can add this to the forum. I just had all 6 of mine changed as I was getting mis-fire on both banks. I have a local garage and the cost for him to do it vs. me was the difference in his labor (about 1.5 hours, in which he also cleaned the MAF and throttle body).

 

The truck runs fantastic, and here's the odd thing...I was having some concern about that harsh or seemingly mis shift between 1st and 2nd gear and since the new coils were installed it's all but vansihed which is GREAT but I don't understand why unless that engine misfire was also creating some issues with the shifting pattern?

 

peter

[IncidentalOffroader]

WOW, you are one thorough SOB! I love you for it.

 

Thanks. It's not easy being anal. Sometimes I hate myself for it.

 

Bowtied's discussion ties it all up for me. Thanks! Does anyone actually have a copy of the TSB, and if so, does it mention the dots?

[IncidentalOffroader]

I can add this to the forum. I just had all 6 of mine changed as I was getting mis-fire on both banks. I have a local garage and the cost for him to do it vs. me was the difference in his labor (about 1.5 hours, in which he also cleaned the MAF and throttle body).

 

The truck runs fantastic, and here's the odd thing...I was having some concern about that harsh or seemingly mis shift between 1st and 2nd gear and since the new coils were installed it's all but vansihed which is GREAT but I don't understand why unless that engine misfire was also creating some issues with the shifting pattern?

 

I suppose if the engine was misfiring badly enough, the transmission was having a hard time deciding if/when it should shift. Like if you kept faking it out by modulating the gas right around a shift point. If the problem is now gone, I'd allow myself to be optimistic that the coil change fixed it. When something major like severe misfiring is going on, all bets are off for everything else working well.

 

These are just my guesses...