Mixed Matched Spark Plugs

[Nine1Sickness]

Sup guys, I just had a question. I just bought me a 03 S2000, and the other day I notice that the car started running kinda weird. So I took out the spark plugs and notice there were 3 NGK Platinum and one Iridium. Shocked, I went and got me a new set of NGK Iridiums. Now it runs 10 time smoother. I was just wondering if running mixed matched plugs would mess up the engine? I have no idea how long the plugs has been in the engine, but I only drove about 500 miles before I changed them out. Obviously the previous owner was very smart, or a total nutt.

[gomarlins3]

I would guess it's best to go with all the same type.

[MattYielding]

I wouldn't think it would hurt the motor, but the reason it was probably running like crap is because the one iridium probably was a replacement for an old/fouled plug, so you were probably running three old plugs and one new.

[turbosix]

did you gap them all ?

[Roger_Rabbit]

Originally Posted by Nine1Sickness

Sup guys, I just had a question. I just bought me a 03 S2000, and the other day I notice that the car started running kinda weird. So I took out the spark plugs and notice there were 3 NGK Platinum and one Iridium. Shocked, I went and got me a new set of NGK Iridiums. Now it runs 10 time smoother. I was just wondering if running mixed matched plugs would mess up the engine? I have no idea how long the plugs has been in the engine, but I only drove about 500 miles before I changed them out. Obviously the previous owner was very smart, or a total nutt.

I had a very similar situation and I replace the spark plugs and it made a huge difference... I still had an issue but it was cause my valves were bent...
It will not hurt your engine to run 4 different plugs, much less 3 of the same and one different...
It will only hurt the performance a little... Bad plugs on the other hand will make it run like crap...

Originally Posted by turbosix

did you gap them all ?

You dont gap the iridium and platinum...

[D1sclaimer]

I think it'd also have to do with how iridiums vs platinums heat up since they are self cleaning plugs designed to last a long time. Im not an expert, but I'm 90% sure thats the case.

And you can gap platinum and iridium plugs. Our OEMs come pre-gapped, but I wouldn't trust them to be right. Always double check the gap.

Denso Iridium FAQ with gap info
http://www.densoiridium.com/faq.php

"
Q: Do I need to set the "gap" when installing a new set of plugs?
A: Maybe. A spark plug part number might fit hundreds of different engines from many different manufacturers. Although the NGK factory will set the gap to a pre-selected setting, this may not be the right gap for your particular engine. The incorrect plug gap for your engine can contribute to a high rate of misfires, loss of power, plug fouling, poor fuel economy, and accelerated plug wear. It is always best to check the gap against the manufacturer's specifications. If adjusting the gap on fine wire or precious metal plugs such as platinum or iridium be very careful not to apply any pressure or prying force to the fine wire center electrode or insulator as they can be damaged. The gap should be adjusted by only moving the ground electrode.
"
http://www.ngksparkplugs.com/tech_su...p.asp?mode=nml

[Roger_Rabbit]

Originally Posted by D1sclaimer

I think it'd also have to do with how iridiums vs platinums heat up since they are self cleaning plugs designed to last a long time. Im not an expert, but I'm 90% sure thats the case.

And you can gap platinum and iridium plugs. Our OEMs come pre-gapped, but I wouldn't trust them to be right. Always double check the gap.

Denso Iridium FAQ with gap info
http://www.densoiridium.com/faq.php

"
Q: Do I need to set the "gap" when installing a new set of plugs?
A: Maybe. A spark plug part number might fit hundreds of different engines from many different manufacturers. Although the NGK factory will set the gap to a pre-selected setting, this may not be the right gap for your particular engine. The incorrect plug gap for your engine can contribute to a high rate of misfires, loss of power, plug fouling, poor fuel economy, and accelerated plug wear. It is always best to check the gap against the manufacturer's specifications. If adjusting the gap on fine wire or precious metal plugs such as platinum or iridium be very careful not to apply any pressure or prying force to the fine wire center electrode or insulator as they can be damaged. The gap should be adjusted by only moving the ground electrode.
"
http://www.ngksparkplugs.com/tech_su...p.asp?mode=nml

Good to know... Everytime I buy plats or iridium it says not to change the gap but I stand corrected... If I did not learn something new everyday there would be little or no reason to get out of bed...