It was such a simple solution i feel like an idiot for even posting. I had a horrible misfire above 3k at over 50% throttle along with a pretty rough idle. The car had bosch platinum plugs which I replaced with NGK laser plats which completely smoothed the idle and eliminated the misfire. I've read several threads with people having similar symptoms and I'm just posting the solution I found. Hope this helps some of you.

adam

 

yep, Bosch = Sh|t, stick with NGK coppers.

 

Yeah I had the same problem with the Bosch Platinum plus 4's when I first got my Maxima, I got them because they worked so well in my 300ZX TT ! Now I use NGK coppers only.

 

did u guys gap them properly? im guesing u did, which is odd
ive had bosch platinums for around a month now and theyve been fine. no misfire or rough idle.
ill probably still go get some NGK soon

 

Why wouldn't you guys use NGK's Platinums? They were designed for your car and last a very long time. The intake is a pain to remove so why use copper plugs. Me not getting this.

 

copper's last only half as long as platinums but are practically dirt cheap. You have to replace them more times, but because they are so inexpensive, you end up saving money in the long run.

 

Me not getting why you have to remove the intake??? Me also not getting why it is a pain to remove the intake??? It comes off within 5 minutes, if that.

Even if changing plugs at 15k, it really isn't a short amount of time, and for those who like doing stuff to their car, no matter how small, it isn't a pain.

 

mE nO No?

The only thing you'd have to actually remove is the canister to remove the rear plug closes to the drivers side which only takes 10 seconds to undo the two 12mm bolts.

on a side note, I ran my best times with Bosch Plat 4.... I didn't notice any difference between NGK copper and Bosch Plat 4's in everyday driving.

 

Before I knew the put in the NGKS, I had the bosch in, and wow did I see some terrible gas milage, after I switched to the coppers, I saw such an improvment like you wouldnt believe.

 

how much $avings are we actually talking about here....

 

$11 for coppers every 30k or $56 for plats every 60k. It's a pretty big difference.

 

why use copper??? they dont last half as long, it is worth the time to buy platinum unless u like changing your plugs more often then normal......

 

how much are platiums and are iridiums better?

 

if u like saving money and don't care about how often u change ur plugs, that's why u use copper.

 

heh, the bosch plugs were put in about 30k km's ago, when my dad still owned the car (and didn't know any better). at the time, the car had a bit of a vibration at idle, and changing the plugs to bosch made no difference. Just recently the car began to misfire, changed plugs and idle is as smooth as when the car was new. give the bosch plugs time, you will eventually notice a performance loss.

adam

 

You got it wrong - if you thought it was worth the TIME, you'd buy copper. But since you think platinum is the best, it is worth your MONEY to not have to change them only twice as often. Also, copper provides a better spark. So besides cost and better performance, you're right: There IS no reason to put coppers in...

 

right! I don't know why this is so hard to get...

 

The reason many like to use copper plugs as opposed to platinum is that copper has a lower electrical resistance than platinum, therefore, more electricity is transferred to the spark instead of being lost to the spark plug. Platinum offers higher resistance, but a longer life, which is why it gets the nod in car engines these days. Iridium combines the life of a platinum plug with the resistance of a copper plug. Essentially, iridium is the best of both worlds, at the price of a copper and a platinum plug put together.

adam

 

Any facts to accompany this???? the haynes repair manual says "NGK PFR5G-11 or equivalent platinum type"
so copper works better but doesnt last as long correct?
what is the life span of iridum plugs??

 

supposedly on par with platinum

 

Honostly I have never heard a mechanic say "Just use coppers, it doesn't matter what all the other mechanics say, or what your Haynes service manual says, or what your owners manual says, or the fact that your Maximas came with platnums." Never heard it...
And that's my $.02 I think this argument is on par with Synthetic oil or not...

 

If coppers really do have lower resistance (which makes sense) then I'd be a bit concerned about how this would affect coil life and ignition performance in general. I used to tune my dual-point '68 camaro to run on different plugs. seems like these new computer controlled ignitions are programmed for a specific plug type.

 

The coils still fire out the same charge, regardless what plug is in there.