dfownz

iTrader: (5)

Hey guys,

I have a 00 5pd Maxima and about six months ago I put in some Denso Iridium plugs which were all gapped at .040 out of the box. Right now (six months later), my engine is starting to misfire and I was under the impression that Iridium plugs will last for around 100k miles.

I've replaced one coil so far and am looking further into this issue now that another cylinder is starting to misfire. I just fixed #5 two days ago and now #4 cylinder is misfiring too.

Do the coils generally tend to die out all at the same time? If so, that sucks and its going to be a lot more expensive than I had anticipated.

So basically, is my gap right and if not what should it be? Also, are there any differences which iridium plugs that I should look for to show for bad plugs?

Thanks,

DF

Metal Maxima

iTrader: (30)

I'm running just fine with the Iridiums...I really don't think it's the plug. Do you have ay codes?

dfownz

iTrader: (5)

Yes, I've had P1320's up the whazoo.

First time it was for the #5 cylinder so I replaced the coil, assuming my spark plugs HAD to still be good.

Now I'm getting the EXACT same codes, but for #4. I'm going to pull the plugs today and see what's up, I was just asking about them, because my buddy that works at Inskip told me that if you swap out plugs on some Volvo's that aren't exact OE replacements that the car will misfire like no ones business.

Do you know what you had them gapped at?

DF

Metal Maxima

iTrader: (30)

Sounds to me as though you have other issues here, likley the coils.

I did not gap them nor measure them as they come pre-gapped.

dfownz

iTrader: (5)

Yeah either did I, just wondering if there some something crucial that I missed somewhere. I guess its just my crappy luck that another coil went the day after I fixed the other one!

How long are iridium's supposed to be good for?

DF

Thanks for your quick response btw.

opanick

iTrader: (1)

do yall recommend the ngk platinums or iridium's?

Metal Maxima

iTrader: (30)

Looks like it.

IIRC, they are good for 60,000K

Metal Maxima

iTrader: (30)

This has been discussed a million times over.

Coppers conduct electricity the best thereby giving you a better spark and the greatest fuel efficency (but not by much) vs. Platinum or Iridiums.

Platinum and Iridiums conduct equally as well, but will last for 60K whereas the coppers will last for 20K...but, as would be expected, they cost 4 to 5 times as much.

IMHO, go with the Iridiums. If I am going to be investing some $20K into one of the most critical necesities in my life, I have no problem shelling out an additional $40 for peace of mind.

dfownz

iTrader: (5)

Yeah I pulled the 3 from the front bank, they were all gapped the same (little past .040 like .042). So must be another damn coil. I even went as far to remove all the wire insulation to inspect the wires coming from the coil-connector.

Everything was perfectly fine.

DF

d00df00d

iTrader: (4)

Not quite....

Iridium is better than platinum in every way relevant to a spark plug electrode: it is more conductive, much more resistant to heat, and MUCH harder and thus able to be used either in a fine-tip design for even better spark, or in a normal-size tip design for ridiculously long life. The ONLY reason platinum was ever used was that the manufacturers didn't have the technology to use iridium cost-effectively.

As for the question of mileage, it depends on which iridium plug you use:

- Plain-Jane NGK iridium plugs (part #s starting with IFR) will spark slightly better than platinums and should be good out to 120k miles and beyond.

- NGK Iridium IX plugs (part #s starting with BKR) have super-fine center electrode tips (0.6 mm), so they will spark significantly better than platinums. The tradeoff is shorter life than the IFR plugs -- about 100k miles, which is still better than platinums.

- Denso's Iridium Power plugs (part #s starting with IK) have the finest center electrodes (0.4 mm) and give the best possible spark but can't be expected to run past 50k miles or so.