Can spark plug brand affect mileage?

[rcy]

Replaced my OE spark plugs on 2006 MDX (which were Denso iridium (I forget the part #) with Bosch Iridium. Fuel economy seems to be suffering from what it was, but I know any number of things could be the cause.

Just curious - all the spark plug needs to do is create a spark to burn the fuel/air mixture. Yet I see many people on various forums claiming that fuel economy suffered or increased when the plugs were changed.

How can one brand of spark plug, assuming same material (copper, platinum, iridium etc.)is used be any different than another brand when they both do the same thing - make a spark?

 

[mattd]

I would have used OEM denso plugs. Thats all we use in honda products. They do not seem to run as well with other plugs. I'd recommend changing them out.

 

[rcy]

Thanks. I was thinking about doing that anyway. Only reason I went with the Bosch is because they were on sale. The Denso are $18 EACH at the stealership.

What's your take on the NGK, which are the other brand recommended in the service manual?

 

[Eddie]

If the heat range and physical dimensions are the same then no.

 

[rshaw125]

Originally Posted By: Eddie
If the heat range and physical dimensions are the same then no.

+1, if there was a difference in mileage it would be very very small.

 

[mattd]

NGK are also an OEM plug. Also good luck with those. Whichever ones come out, go in. I have had some V6 hondas also come with half denso half NGK. I cant recall the part number however, but make sure they are iridium.

And yes, they are quite pricy but last a LONG time. They will go well past the service interval.

 

[bourne]

The only other brand of plug I recommend in Asian vehicles other than Denso would be an NGK. If cost is an issue, try www.rockauto.com for OEM matching plugs. I personally prefer an NGK plug over any other brand.

That being said , I decided to roll the dice on some new design Bosch Iridiums for the Civic in my signature (were $2/ea after MIR). So far seems to be working just fine. No difference in mpg/power.

 

[heyu]

Originally Posted By: mattd
I would have used OEM denso plugs. Thats all we use in honda products. They do not seem to run as well with other plugs. I'd recommend changing them out.


+ 1

 

[AVB]

Bosch plugs are known for that. My dad was doing the plugs on his old Tacoma, I told him to get Densos or NGKs. He came home with some Bosch platinums, he used them for about a week before he put some Densos back in.

 

[Bgallagher]

Originally Posted By: mattd
I would have used OEM denso plugs. Thats all we use in honda products. They do not seem to run as well with other plugs. I'd recommend changing them out.

Same thing with AC-Delco and GM vehicles. Other brands just don't seem to work. I'd swap them out. Also, how do the wires look? Did you dab some dielectric to ensure a good seal?

 

[dparm]

The brand is irrelevant. Gap them correctly and get the correct heat range. I have run Bosch, Denso, NGK, and Autolite. Zero difference.

I have never understood why huge debates break out on auto forums about one brand being "better" than another. Protip: NGK used to make their plugs under license from Bosch.

 

[ARCOgraphite]

If you have waste spark ignition (e.g: one coil firing 2 plugs and one plug fires "backwards") then having a non fine wire in the negative firing hole is important to reduce misfiring and improve mileage and torque. This is common on certain V6 where three coils are used to fire six holes. With COP (individual Coils On plug) they are not sensitive to firing direction but more sensitive to gap and ignitability. YOu want Ir finewires (denso or NGK) on engines with small COP coils for easy ignitability.

 

[rcy]

Originally Posted By: Bgallagher
Same thing with AC-Delco and GM vehicles. Other brands just don't seem to work. I'd swap them out. Also, how do the wires look? Did you dab some dielectric to ensure a good seal?

Coil packs. Didn't use any grease. Should I put a dab on the new Denso plugs before I mount the coil packs?

 

[rcy]

Originally Posted By: ARCOgraphite
. With COP (individual Coils On plug) they are not sensitive to firing direction but more sensitive to gap and ignitability. YOu want Ir finewires (denso or NGK) on engines with small COP coils for easy ignitability.


So the Bosch, where there is no wire visible, would not work as well as a plug where one can see the wire?

 

[Bgallagher]

Originally Posted By: rcy
Originally Posted By: Bgallagher
Same thing with AC-Delco and GM vehicles. Other brands just don't seem to work. I'd swap them out. Also, how do the wires look? Did you dab some dielectric to ensure a good seal?

Coil packs. Didn't use any grease. Should I put a dab on the new Denso plugs before I mount the coil packs?

I'd do it for good measure. Helps the seal and prevents the plug from sticking

 

[VK56VD]

How many miles were on your mdx when you replaced the oem spark plugs?

 

[HerrStig]

I used Bosch plugs for years in VW and Volvo products.. when I bought my first SAAB it came with NGK. I tried Bosch in the car, after all it had Bosch injection, and went back to NGK. The SAAB guys apparently knew what plug the engine needed. Now I use NGK in everything including my German motorbike. My Honda mower came with an NGK. I'd put an NGK Platinum in my Briggs L head generator if the right one were offered. As it is Champion makes a platinum which works.

 

[rcy]

Originally Posted By: Spartuss
How many miles were on your mdx when you replaced the oem spark plugs?


Just under 200 000 kilometres.

 

[VK56VD]

What condition were the original's in? A lot of times the original's can go past that mileage without any issues.

 

[rcy]

Umm...brownish? Lol...I can't remember and didn't look too closely since I was replacing them anyway. They did have that brown rusty colour around the ceramic base that is common (and normal and not indicative of any problems).