IncidentalOffroader

How old was the battery? In my experience, older batteries fail very suddenly.

For the first symptom, I would check the wheel balance like you suspect. I would look at the tires for obvious things like something stuck in the treads, a chunk of rubber missing, a flat spot, uneven wear, and cupping. I would look for signs that a weight fell off (a "shadow" on the rim where it used to be), and do a visual check to see if a rim is bent. Then I would get all 4 wheels rebalanced. If that didn't work, I would check the front bearings for excessive play... even though you repacked them recently, they might be worn. Then I would take a look at the tie-rod ends and steering linkages. Any of these problems may cause inconsistent symptoms. Resonances in general are capricious. Differences in road surface, load, speed, temperature, etc. can easily de-tune a resonance. Even if the vibration goes away after a few minutes under consistent conditions, maybe a bad bearing started resonating, heated up due to the extra motion, and then stopped. Don't take this last scenario seriously! it's only a far-out speculation that I just made up as an example... what I'm trying to say is, trying to find the conditions for the vibration and diagnosing it from there would be much harder than just addressing the usual suspects from the beginning. As for the second symptom, I'd suspect the rotors too. Although you had the brakes done recently, rotors can warp for reasons other than wear. It should be a simple check and a routine fix.

My 2001 SE sometimes locks by itself. My security system is stock. I agree that it's a nuisance while camping. I've never seen it self-lock when the doors are open, but a few times it did when we were sleeping inside, after about 15minutes of inactivity. If we then manually unlocked a door from the inside, the alarm would go off and make us the campground pariahs. We had to remember to use the remote to unlock them. I never believed it was malfunctioning, and just chalked it up to us not "understanding" the security system. Admittedly, I haven't thoroughly looked into this to see if the behavior is consistent.

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...

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?

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.

I remember there was a Consumer Reports article that listed the brands of gas that varied their additives with octane. It came out back in the late 90's, so the info might be out of date by now. But I wish I could find a similar list for today. As for using premium, I think we all agree that "high octane does nothing for you if your engine isn't prone to knock." Some engines are prone to knock by design (ex. high-compression ratio). But engines can develop knock problems with age or malfunction. With age, carbon and soot deposits can build up in the combustion chambers, which retains heat, elevating the temperature, and inviting pre-ignition. One could also argue the deposits increase your compression ratio. As far as malfunctions go, one example is bad timing (obviously), another is the EGR valve, which is supposed to route some exhaust gas back to the intake air specifically for the purposes of reducing pre-ignition. Having said all that, if you are happy with results with premium, there's no reason for you to stop using it because it doesn't fit our expectations based on what we "know".

Are any codes pending? Pending codes don't light the MIL until the fault is detected multiple times, and then they get promoted to trouble codes. My '01 was severely misfiring and the computer knew it because it was blinking the MIL. But the misfire didn't show up in the trouble code readout. It was in the pending list. Make sure your code reader is showing you pending codes.

I usually buy Chevron because of the Techron. But I make it a point to occasionally buy other major name-brand gases like Mobil or Shell, the reason being this vague notion that additives from other refiners might be better in some other way. Diversity is good. Another reason is to have experience with other brands of gas in case I can't find a Chevron station. I'll have an idea of a 2nd or 3rd choice, and what to avoid.

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.

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

Those are great examples, especially the second clip. Assuming one of the rear wheels were on the ground when the front wheel started spinning, the LSD left you just as stuck as an open diff! I thought an LSD would transmit at least some of the power to the non-spinning wheel, but I guess it wasn't enough. I had a friend tell me that with LSDs in general, once a wheel starts spinning, it essentially gives up and doesn't transmit any power to the non-spinning wheel. Is this true, or did I misunderstand him? If this is true, I guess the LSD is only good for keeping you moving with less traction and preventing things from degenerating into wheel-spinning. But once a wheel starts spinning, it does nothing for you. This would be the exact opposite of a locking diff, where you would only lock it when a wheel is spinning. Have I got this right??

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