I've had a problem with my 99 Max GLE since I bought it about a year ago. Under extremely hard acceleration (pedal to the floor) it would start bucking or jerking as if it was misfiring like crazy. When idling it was fine and under light, normal or somewhat hard acceleration there was no sign of a problem...only when I would floor it. I found that it had Bosch platinum plugs installed, so on the advice that I've seen given to others in the group, I shelled-out the big bucks for a set of NGK platinum plugs (the exact ones called for in the owner's manual). I installed the new plugs yesterday and when I took it for a test drive I was thrilled to see that I no longer had the above problem, now it really goes when I tromp down on the gas pedal. However, I now have a new problem: Now it seems to lope or misfire intermittently at idle speed. If it's in neutral or park it isn't really noticeable, but when in drive or reverse it stumbles so badly that it seems like it might stall. It doesn't seem to miss when giving it gas, only when at idle speed. Any ideas what I should check for?
Sounds like you need new ignition coils. This problem is very common on 99 Maximas. Search the group for "hesitation", "coils", "misfire" and you'll find a lot of pertinent information.
The short of it is that you have to replace all 6 coils, at a wholesale price of about 60 bucks a piece... call Courtesy Nissan for good prices and service.
Sounds like you need new ignition coils. This problem is very common on 99 Maximas. Search the group for "hesitation", "coils", "misfire" and you'll find a lot of pertinent information.
The short of it is that you have to replace all 6 coils, at a wholesale price of about 60 bucks a piece... call Courtesy Nissan for good prices and service.
I just had a similar problem, but, sort of, in reverse (see the recent "Maxima 99 - knock sensor code..." thread). There was one thing that seemed like a small detail so I didn't write about it: initially I had these misfire events with the OEM NGK plugs, which also intermittently appeared at high engine speeds, not only at idle. (You may not feel them at high speed with auto transmission, but with a manual they are quite noticeable.) Then I replaced NGKs with a set of new Bosh +4 plugs, and the problem instantly got worse (not as bad as you describe, but quite similar - especially at high revs/hard acceleration). Once it got worse, I was able to locate *one* cylinder which misfired at high engine speed (code P0303 showed up, which clearly pointed to the third cylinder). So I replaced that one coil (65 bucks at Autozone), and the problem was instantly gone. I still have the same Bosh +4 set and I have no problems whatsoever.
My guess is that Bosh +4 is just fine if all coils are OK. However, they (Bosh plugs) have wider gaps than NGK, so they need a higher voltage to work normally. If a coil is weak they can't get normal voltage, so misfires are more often than with NGK. This difference actually helped me to narrow down to one cylinder: the error code seems to register only when the problem gets really bad (I believe someone wrote it takes three faulty engine revs *in a row* to detect a miss). This is what was happening at high revs with Bosh plugs in my case, apparently.
So, if I was in your situation, I would (a) clear the codes, (b) put the old Bosh plugs back, and (c) drive hard until the engine light turns on, then take the codes to see which exactly cylinder(s) was missfiring. Then I would replace the coil(s) only in that cylinder(s). This is not a very well educated advice though, and it would be better if someone could confirm that this would be a safe thing to do. I went to AutoZone to read and clear the codes, they did it free of charge.
The alternative procedure would be two step: (1) return Bosh plugs to the front cylinders only and see if the things get worse. If yes, get one new front coil and test it in each cylinder to see which coil gives you the problem. (2) if returning Bosh plugs to the front does not make any difference, then buy one new back coil and test it with each back cylinder...
What you can do is unplug each coil one at a time. As you unplug coils, you should notice the engine stumble more and more with each good coil. When you unplug the bad coil(s) there should be no change in the way the engine runs.
This would work if his coil was totally dead (one cylinder would be missing all the time). Apparently this is not the case: the coil gives good sparks in most cycles and misses just from time to time, and relatively rarely at that. I had the same thing, and I couldn't figure which coil was bad by unplugging it: whichever coil you disconnect the engine runs worse.
Otherwise I wouldn't have to invent the idiosyncratic procedure with returning half of the old Bosh plugs back (in my other post in this thread). Huss, being, well, Mohrens...
your point is valid. The procedure I outlined will only work if you have a consistent misfire. I'm just surprised that with any of these misfires, we don't see the CEL trigger more often - it takes a severe misfire condition to trigger the CEL... I've seen 99's that are just not driveable because of the misfires and yet no CEL.
I never got any codes with either set of plugs, so the first procedure won't work, but the alternative procedure that you indicated will probably work so I'll give that a try. Thanks!
Higher voltage is only needed to ignite the spark, and there is no 'higher voltage->higher current' connection in this case. The current through the spark does not depend on the gap, it is restricted by the plug's resistance. So I don't see how a wide gap can kill a coil - even if the coil is already bad.
The way these coils "fade" clearly suggests that some semiconductor components get slowly deteriorated in them (and that's why the problem gets worse when the coils are warm). Just remember that Maxima's "coil" content is not just a wire coil, but a package consisting of a coil and some electronic circuit that, in earlier generations of cars, was a part of the ignition module. What can possibly happen to a transistor if the coil _doesn't_ fire? It's exactly the other way around: the more it fires the more deterioration.
(By the way, some old ignition modules had a similar problem: they were suddenly getting sloppy and then dead when their temperature exceeded certain limit, but started working again after some cooling.)
The above is not supposed to mean that driving with wide-gap plugs is good when your coils are bad. More misfires means more gas burning in the converter, or even blowing up in the exhaust pipe, which is pretty bad.
HM
PS: I could easily imagine that a too low plug resistance could kill a coil because such plug would develop a too high current. But I don't believe for a second that Bosh could possibly market a plug with a too low resistance. They should know more about plugs than anybody else: after all, they were the ones who invented the plug. Their website says Bosh +4 fits Maxima 99, so I am sure it does - as long as all coils are good. PPS: I have no idea how hot Bosh +4 are, and how would they behave being driven continuously at high revs. I don't race, so I don't care. I guess the OEM NGK wouldn't be that good for racing anyway.
?? What do you think increases the current/load? It's a combination of the air gap setting and the cylinder pressure. Open up the gap and watch the firing voltage rise. If the mJ of curent remain the same and you double the firing voltage, what do you think that does to the load on the componets?
??? Actually most of the resistance is the air gap not the plug itself. Notice the plug electrode isn't grounded at all so whatever "resistance" is in the plug is miniscule compared to the air gap it must cross to complete the circuit.Try measuring the resistance of the air gap.
Which is accellerated by using the wrong/wornout plugs.
Same senerio. Most modules died an early death by being overheated from firing worn out (extra wide gap) plugs.
Again the majority of the resistance is in the PLUG GAP, not the plug itself. And grounding a coils output doesn't cause a problem, firing an "open" coil can.
That wouldn't kill a coil but could cause an EMI problem on a car with electronic controls.
LOL so you believe that these plugs are OK because BOSCH says they are? Notice that there isn't one single OEM that has EVER used these type of BOSCH platinum plugs and the ONLY reason people want to use them is they are cheaper than the real NGK platinums! BOSCH makes some great products, these plugs just aren't one of them.
I said what I thought: higher voltage is needed only to *ignite the spark*, i.e., to ionize the air/fuel mix between the electrodes. Once the plasma channel is formed, the resistance is so low that it doesn't matter as compared to the resistance of the plug (remember - there is a resistor in the central electrode).
Most likely nothing.
See above - this is true, but only for pre-spark conditions. The resistor, again, is inside the central electrode.
Maybe, but unlikely. If the plug doesn't fire, there is less load on the power transistor (no current), not more.
I can't see why. (1) The coil will develop full voltage pre-spark whatever the gap width is. (2) The element that sends current to the coil doesn't "sense" the voltage anyway (it's in a different contour).
I don't think either may cause damage, missfires in most engines are a norm. It is more likely the quality of the elements used in the assembly that matter. See, these Han-whatever coils fail and Mitsubishi don't.
That would very likely kill the semiconductor components: a too steep voltage drop and your transistor gets melted.
Well I am not marketing for Bosh here :)
I just don't think there is much of a difference, just German manufacturers use and recommend Bosh plugs and Japanese use and recommend NGK. The amount of platinum used in either plug is too small to justify the price anyway. They'll be all two bucks a bunch when they go off patent.
Well, I tried opening up the coils and cleaning them as indicated on the maxima.org thread, but it did not help at all. I didn't expect that it would. I did receive my new coils today from eBay though. I just installed the new coils and all misfire issues are now resolved, the car is running perfectly.
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