THAT Spark plug gap was still running the engine mostly fine !

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Originally Posted by walterjay
We have a Hyundai SantaFe with 165,000 miles on the original iridium plugs. Runs perfect. I can only imagine the gap on those.


Pull one. You will be surprised at how big of a gap you now have. Plugs are cheap. Coils, not so much.
 
I agree, I just wanted for Rockauto to have a deal, and combined that with an Autolite rebate for Iridium plugs for my Sonata. Been running great. Replaced at about 65k.
 
The bad about coil on plug (at least on my old Mercedes M272 V6) is them being able to adapt so well to widening gap is that it will run just fine up until the last minute then leave you with needing new plugs ASAP.

My C300 had 80k change intervals and I was closing in on 85k, I was between services so figure it could wait until my next oil change that was about 2 months down the road (prior oil change was ~78k miles). Car was running just fine but pretty much overnight went from starting fine while cold to misfiring horrifically for the first 10-15 seconds of every cold start, after about 4-5 days of this it finally triggered the CEL with misfire codes on 5 of the 6 cylinders. New plugs and everything went back to normal, I got my old plugs back and there was pretty much no electrode left. Never any perceptible misfires while driving, just the cold start issues.
 
Originally Posted by walterjay
We have a Hyundai SantaFe with 165,000 miles on the original iridium plugs. Runs perfect. I can only imagine the gap on those.

Just changed the plugs on my G35 with 121k miles. These were the factory plugs too. 5 of the plugs were gapped at 0.040" and 1 was at 0.045". The spec gap is 0.040".
 
Originally Posted by pezzy669
The bad about coil on plug (at least on my old Mercedes M272 V6) is them being able to adapt so well to widening gap is that it will run just fine up until the last minute then leave you with needing new plugs ASAP.

My C300 had 80k change intervals and I was closing in on 85k, I was between services so figure it could wait until my next oil change that was about 2 months down the road (prior oil change was ~78k miles). Car was running just fine but pretty much overnight went from starting fine while cold to misfiring horrifically for the first 10-15 seconds of every cold start, after about 4-5 days of this it finally triggered the CEL with misfire codes on 5 of the 6 cylinders. New plugs and everything went back to normal, I got my old plugs back and there was pretty much no electrode left. Never any perceptible misfires while driving, just the cold start issues.

The 272 should have plugs done at 60K intervals. The last one I did showed plugs as part of the 60K service in the manual.
 
Originally Posted by walterjay
We have a Hyundai SantaFe with 165,000 miles on the original iridium plugs. Runs perfect. I can only imagine the gap on those.


Iridium plugs can go a lot longer than people think. There is a guy on the 8th gen Civic forum who has over a million miles on his Civic and he has close to that amount of mileage on his iridium plugs. He pulls them out every once in a while to check them and clean them and puts them back in since they are still going strong. I foolishly changed my original iridium plugs in my Civic at 80k, long before they needed replacing, and went with lesser quality iridiums from Champion. A few years later I bought another set of OEM iridiums (which are NGK laser iridiums) and will never need to change them again (I only drive 5k a year on this car)
 
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