Do Spark Plugs Make A Difference

[m3f_gasolina]

I got brand new Denso Iridiums. The cold idle misfire is still there. Plugs will not make a noticeable power difference, no matter what they are made of or how many electrodes they have. Gap will change the required voltage for spark to jump, but it really doesn't matter since the voltage is controled by the coil. So engine power at small gap at x Volts = engine power at large gap @ x volts, as long as the given voltage is enough to jump the large gap as well.



One benefit from multiple electrode spark plugs is that they won't foul as easily as single electrode spark plugs. But in an engine like ours, that really isn't a problem. Maybe in an old iron block "sludge-factory" engine (and even some new Toyota engines) where carbon deposits, soot and sludge get up into the combustion chamber it would be advantageous to run Bosch 4 electrode plugs or splitfires.



Another thing to think about is that the spark just initiates the flame kernel during the combustion process. It doesn't actually act on the combustion per se. The gas dynamics inside the cylinder (swirl and tumble) caused by good intake valve and port design are the most significant factors in combustion. Fuel delivery is the next most significant factor. There is a lot of theorys regarding this, depending on who you ask (and what they have to sell). Now Multiple spark discharge can help combustion by creating more kernels and aiding a faster combustion (but this has some noise ans soot issues still), but faster combustion doesn't necessarily mean a more potent engine. Most developments in spark technology are focused for emmisions, not specific engine output.



anyway, buy good spark plugs so you don't have to change them too often. Don't expect to be faster though.

[m3f_badgtho_2cb87af10e]

Ok :nixweiss: Must be the gap then which means the gap on all OEM plugs is wrong. What else would explain a rough idle from the factory and it magically went away with different plugs?





it doesn't mean that the oem gap is wrong at all. It means that copper is softer than the other mentioned metals and therefore the heat adversely affects it and the optimal gap is lost. Did you check the gap on the OEM plugs when removed? I would virtually guarantee that it was off. Many many many other things can account for rough idle... dirty plugs, mis gapped plugs, plugs who's gap has changed in relation to others. As far as changing the gap, in some cases much is to be gained by increasing the gap, however the most is gained when the gap stays where it is set. the arguement for the harder metals in plugs is there ability to remain consistent.

[m3f_AMPowerJ_e8f979e5cd]

it doesn't mean that the oem gap is wrong at all. It means that copper is softer than the other mentioned metals and therefore the heat adversely affects it and the optimal gap is lost. Did you check the gap on the OEM plugs when removed? I would virtually guarantee that it was off. Many many many other things can account for rough idle... dirty plugs, mis gapped plugs, plugs who's gap has changed in relation to others. As far as changing the gap, in some cases much is to be gained by increasing the gap, however the most is gained when the gap stays where it is set. the arguement for the harder metals in plugs is there ability to remain consistent.



GUYS - read my posts! Brand new OEM plugs = bad idle. Brand new Denso plugs = good idle. Nothing was worn, nothing wore out, nothing was dirty. Apples to apples comparsion. 0 miles plugs both times.



I am willing to chalk it up to luck or something peculiar to my car though.



Don't buy Denso Iridiums. They ****! Go get some copper Champion plugs in the lawnmowers section of Sears. They are all the same. Trust me. Now is everyone happy? :chair:

[m3f_badgtho_2cb87af10e]

GUYS - read my posts! Brand new OEM plugs = bad idle. Brand new Denso plugs = good idle. Nothing was worn, nothing wore out, nothing was dirty. Apples to apples comparsion. 0 miles plugs both times.



I am willing to chalk it up to luck or something peculiar to my car though.



Don't buy Denso Iridiums. They ****! Go get some copper Champion plugs in the lawnmowers section of Sears. They are all the same. Trust me. Now is everyone happy? :chair:



How did the gap on your old plugs compare to the gap of those installed? Did you check the gap on those removed. Were all 6 consistant? If that was the case after 30k i would be very surprised. Copper is soft, its ability to maintain a consistent gap is weak compared to platinum or other harder metals. Those are just its properties as a metal.

[m3f_AMPowerJ_e8f979e5cd]

How did the gap on your old plugs compare to the gap of those installed? Did you check the gap on those removed. Were all 6 consistant? If that was the case after 30k i would be very surprised. Copper is soft, its ability to maintain a consistent gap is weak compared to platinum or other harder metals. Those are just its properties as a metal.



My point is that I am not saying I had a rough idle after 30K miles on my old plugs. I had rough idle after 0 miles on the plugs so the copper moving and not retaining the same gap is a moot point.

[m3f_95blkbimm3_9842002abc]

so would putting a plasma ignition coil ...http://www.aatuning.com/garagesale/default.cfm



could that negatively effect horsepower?



would you be able to run any type of plug as long as the gap was the same...since the power was increased?



if this was true, i would run whatever was the most heat tolerant, and just push tons of voltage through it

[m3f_eXpLiCiT_4_fb030f9c5e]

Take one out and see if you notice a difference. :thumbsup:

[m3f_adevera86_be2395d739]

has anyone ever bought denso iridiums ik20s off of ebay? they are like 60 bucks instead of 150? if so who's a recommended seller and are they new and original

[m3f_Michael-Dallas]

The basics is that a more powerful spark will create higher cylinder pressure which will create more power. The power of a spark is determined by its voltage, i.e. more voltage = more powerful spark.



I disagree -- gasolina has it right. In addition, spark intensity is directly proportional to compression ratio. The reason you want a more powerful spark is to ensure the a/f ignitability under high compression (our motors are 11.5:1 compression ratio).



Cylinder pressure for the power stroke depends on how much a/f is burned (i.e. more air and fuel, advanced ignition timing).



As far as spark plug selection, I'd select a platinum-tipped plug that has a big electrode such as NGK.



Michael.

[m3f_Michael-Dallas]

if this was true, i would run whatever was the most heat tolerant, and just push tons of voltage through it



A spark plug's heat range merely indicates the rate at which the spark plug removes heat from the combustion chamber. It has very little relation to ignition voltage.



You want a heat range that is appropriate for the application. If the heat range is too cold, then you will foul the plugs as spark plugs need to be in a certain temperature range in order to be self-cleaning (fouled plugs can cause mis-fire). If heat range is too hot, then you will run the risk of detonation and/or pre-ignition.



Michael.

[m3f_Michael-Dallas]

Ok :nixweiss: Must be the gap then which means the gap on all OEM plugs is wrong. What else would explain a rough idle from the factory and it magically went away with different plugs?



1- Factory may have used incorrect heat range and it's not uncommon. Many B13 SE-R owners complained about rough idle after driving a new car off the lot. The culprit? The SE-R's sat in lots for months at a time and they were only started to move in short distances. If a car is driven short distances often and the plugs never reach operating temp, then they will foul. Nissan's fix to this problem? Retro-fit the SE-R's that sat on lots w/ a hotter range plug. In fact, all of Nissan's owner's manuals specify a "factory" heat range spark plug part no. in addition to a 1 range hotter and 1 range colder plug. It is up to the owner to decide which heat range to use.



2- Spark plug gap may be wrong. Different metals have different conductivity. A platinum-tipped plug w/ a 40mm plug gap is equivalent to a copper-tipped plug w/ a 30mm plug gap (I forget the exact numbers and unit of measurement) in regard to ignition intensity. The S54 is a high compression engine at 11.5:1 so using the correct spark plug gap is imperative.



3- NEVER trust the gap on a new spark plug to be correctly set out of the box.



Michael.

[m3f_AMPowerJ_e8f979e5cd]

has anyone ever bought denso iridiums ik20s off of ebay? they are like 60 bucks instead of 150? if so who's a recommended seller and are they new and original



Yeah. That's where I bought mine.

[m3f_San Diego _b8e3666b37]

Wow, I never new this topic would stir so much controversy, thank you all for responding so passionately.

[m3f_95blkbimm3_9842002abc]

3- NEVER trust the gap on a new spark plug to be correctly set out of the box.



Michael.



ok, i've never done spark plugs before, so what is the 'proper' way to gap your spark plugs? get out a ruler and a screwdriver? lol yes, i'm kidding there,



isn't there like a round looking thing with someting that looks like staples around it, isnt that a spark plug gapper, and if so, how do you 'open' or 'close' the gap?

[m3f_Eric1855_e8e56eaefb]

ok, i've never done spark plugs before, so what is the 'proper' way to gap your spark plugs? get out a ruler and a screwdriver? lol yes, i'm kidding there,



isn't there like a round looking thing with someting that looks like staples around it, isnt that a spark plug gapper, and if so, how do you 'open' or 'close' the gap?



They sell spark plug gapping tools at Autozone, PepBoys etc...they are pretty cheap. There are different types that just allow you to move the electrode up and down to change the gap.



Then you want to use a gap measuring tool or just use some feeler gauges to determine the proper gap.