well I really wanted to do it, but the dealer wants too much, the shop has no clue if the gap needs to be reset
Then find another mechanic. Any mechanic tells you he has no idea if the gap needs to be reset has no business working on cars.
The car runs smoothly now…but when plugs get old you’ll get worse gas mileage…less acceleration…hard starting…and may even throw a engine code. This is NOT a good idea. You need to change the plugs when due.
ALL plugs are pre-gapped. The problem is…that some plugs are used for multiple vehicles and the gap may be different for each of those vehicles. Plus there’s always the danger of something happening during shipping that may cause the gap to change. Last tuneup I did on my 4runner…1 of the plugs was way out of wack…and 1 was a little. The other 4 were spot on.
does any one know what the OEM plug is on this car (2009 mazda6 V6), maybe if order the part from dealer, would it come pre-gapped to mazda spec and I don’t have to re-gap it?
I don’t trust shop to re-gap the NGK without damaging the tip
I don’t want to put the NGK in if gap is different than mazda specs, although some say this is perfectly ok??
I think next time I buy a car I want a car easy to change spark plug on.
does any one know what the OEM plug is on this car (2009 mazda6 V6), maybe if order the part from dealer, would it come pre-gapped to mazda spec and I don't have to re-gap it?
You still NEED to check the gap. There are times where the plugs are pre-gapped from the factory…but something happens in shipping that causes the gap to change. Keep the plugs you have and have a competent mechanic gap them before they install them. This is NOT rocket science.
I think next time I buy a car I want a car easy to change spark plug on.
Good luck with that. Don’t buy a transverse mounted V6. Stick with a 4-cylinder or a forward facing rwd V6.
does any one know what the OEM plug is on this car (2009 mazda6 V6), maybe if order the part from dealer, would it come pre-gapped to mazda spec and I don't have to re-gap it?
I already gave you a link right to the correct page of the owners manual for the plug number. What else do you want us to do?
I did some digging, that part number is now called ZZJ118110, which is a denso iridium plug pregaped at 0.032,
I’m going to return the NGK plugs and maybe get the deno plugs from a mazda dealer, hope it’s pregapped to mazda specification, or I will have to get it re-gapped.
You can do what you want, but if you regap them with the tool as shown by BustedKnuckles the way he shows, you won’t have a problem. I just don’t like that particular tool for measuring the gap. The wires are secured at both ends so they are not flexible, I prefer the type of tool that opens up like a feeler gauge but has an L shaped wire on the end. That wire is more flexible and less likely to damage the tip. Go gently when measuring in either case.
But here is the bottom line, if the spark plug fires while exposed to a fuel air mixture that is within the LEL (lower explosive limit) and UEL (upper explosive limit), then the cylinder fires. It does not matter how hot the spark is as long as it is hot enough to cause ignition, the burning fuel does the rest.
As the gap grows, it gets harder for the coil to create a spark that will jump the gap, so too much gap can lead to misfire. If the gap is too small, the size of the spark could be too small and may hit an area of the swirling gasses that is either too rich or too lean to ignite, another misfire.
Back in the days of the Kittering Ignition systems (points), it was hard to develop a spark greater than 25kV, so spark plugs were gapped at 0.030" and would often misfire at any gap greater than 0.040". The soft iron used in the tips (and lead used in the gas) meant that spark plugs had to be changed every 12k miles.
A gap of 0.044" is more than adequate to ignite the more uniform fuel air mixtures injected into todays engines. Opening the gap to 0.051" will not provide any benefit at all. The larger gap will yield a slightly hotter spark, but you are already so over the minimums that its like driving a thumbtack with a jackhammer and you want to get a larger jackhammer.
BTW, you might check with the dealer to see if there have been any TSB’s that may call for reducing the gap. The larger gap will create a hotter spark when it actually sparks, but a less reliable spark because the conditions for creating the proper corona for the spark have less latitude, or margin for error.
I did some digging, that part number is now called ZZJ118110, which is a denso iridium plug pregaped at 0.032,
I’m going to return the NGK plugs and maybe get the deno plugs from a mazda dealer, hope it’s pregapped to mazda specification, or I will have to get it re-gapped.
I think you’re getting all worked up for something very very trivial. And there’s no guarantee the plugs you get from the dealer will be properly gaped either. They may be set at the factory, but it doesn’t mean they’ll be correct once at the dealer.
If you vehicle recommends Iridium plugs…then use them. NGK or Denso probably don’t make a non-Iridium plug anyways. My wifes Lexus has Iridium plugs. I replaced them at about 90k miles. And YES I CHECKED THE GAP. It’s NOT a big issue. If you think the tip could be damaged by checking the gap…then get a set of plastic feeler gauges.
The figure of .032 sounds awful tight to me for a modern era car. Forty or fifty years ago that would be considered normal.
You need to check the underhood sticker as that should have spark plug info on it.
The underhood sticker always takes precedence over other info; including the factory service manual.
I’m worked up because i can’t find a plug pre-gapped to the mazda specs. and i don’t have the tools to gap it and measure it without breaking the iridium tip, some even say i’m not supposed to regap iridium spark plugs. on top of that they make the car so complicated to change spark plugs. what used to be a easy DIY $20 job with a spark plug socket wrench is now $200-$300 at the shop.
I’ve had to re-gap just about every spark plug I’ve ever purchased; short of the fluke sets now and then when the stars were all aligned just right. Every plug that I’ve purchased for my Lincoln comes out of its box at about .045. The factory spec is .054 so ergo, they get regapped.
Re-gapping a plug is nothing to fear. Even something like a pair of needle-nose pliers or sidecutters can be used to bend the side electrode. The main thing is NOT to apply pressure to the center electrode.
One of the spark plug manufacturer sites (Bosch or Autolite if I remember correctly) has a picture tutorial about adjusting the gap.
They show the gap being narrowed by tapping the spark plug on a tabletop. How technical is that…
The reason plugs have been a pain to replace over the past 30 years is because of transverse mounted engines. This makes getting to the back bank of plugs very difficult. Companies like Nissan actually tilted the engine a little to make the job easier. Some companies you have to have a lift and get to the plugs from underneath. Being that said…the only vehicle I found difficult in the past 30 years was my wifes Lexus. The engine is a tight fit and those back plugs are a bear. The plugs on my 4runner are very easy.
This is just so trivial. But consider another alternative that is better than no plugs at all:
Replace just the ones you can reach. I don’t know the config of your vehicle, but if you can reach the front 3 easily, and 2 of the rear 3 easily, do the 5 and leave the 6th one in.
DIY, allows you to keep your cheapskate trophy, and you have drastically reduced your issue of bad plugs, or plugs that weld to your engine…except for that last one?
Spark plugs get changed infrequently, especially when the OEM plug is platinum or iridium. I don’t find it is worthwhile to save a few bucks on plugs by buying anything but OEM. NGK and Denso make many varieties of platinum and iridium plugs so it is always important on Japanese cars to get the exact replacement plug. I can buy NGK plugs for my 2012 Mazda for 12 bucks each at the auto store but the correct plugs are only available at the dealer for about $25 each. Don’t be cheap. Buy the right plugs at the dealer and, as a bonus, they may even gap them for you!
I can buy NGK plugs for my 2012 Mazda for 12 bucks each at the auto store but the correct plugs are only available at the dealer for about $25 each
Then I suggest you find a different auto store. NGK and Denso are the OEM plugs for Mazda. Mazda does NOT make spark plugs. They have NEVER made spark plugs. They are made for them by NGK or Denso…PERIOD. If you go to a GOOD parts store you can get the EXACT SAME PLUG AS THE OEM PLUG the dealer sells for 2-3 times the price.
i checked the mazda oem plugs would only cost me $48 for 6 as opposed to $60 for the NGK laser iridium I bought… and I was told they were already gapped at the factory for mazda, so I don’t need to regap them… hope that’s true.
I’m going to measure my MPG for a while see if there is a reason for me to change the plugs… maybe only do it when MGP drops… one thing with my car the catalyc convertor is bad, it’s generating a check engine light and some code I can’t remember… I hope that doesn’t mean the plugs are due to be replaced??
I had K&N filter on the car before, and another car, both car start developing a catalyc convertor check engine light, I think I will never use K&N air filters again!
You keep missing the point. It doesn’t matter if the plugs were pre-gapped. The cap can change during shipping. I’ve seen it more times then I care to remember. There isn’t a good mechanic in the world who wouldn’t check the gap of a plug before they install it.
Those OEM plugs from Mazda are probably NOT Iridium plugs. So the copper NGK plugs you buy are the local parts store will cost you about $24.
@MikeInNH - The correct plugs at the Mazda dealer are also NGK plugs but they have a design and stock number that I cannot match at the auto parts store. I stand by my statement above.
The correct plugs at the Mazda dealer are also NGK plugs but they have a design and stock number that I cannot match at the auto parts store.
Mazda may have their own number designation. You can find the EXACT plug made by NGK at any parts store that carries a good supply of NGK plugs. What Mazda is doing isn’t anything. The purposely change the number of the plug so you have a hard time matching it. But I GUARANTEE you that you can buy the NGK OEM plug at a decent parts store.
Start here to find the number you can take to the parts store.
