Denso Iridium spark plugs

[carguy84]

Well, I thought I would give these a try since my car has about 30,000 miles on it and a lot of them with the S/C. They are a bit pricey at $12.00 but supposedly they are worth it.

I installed them last weekend, and have seem to develop somewhat of a stutter when I'm coasting and then I hit the gas, or if I take a turn onto another street and hit the gas after I turn it seems to stutter for a second like it's knocking or misfiring, but if I give it more gas it starts to accelerate like normal. I dont know if this is due to the Spark Plugs or something else, anyone else have experience with this?

I have an ECU real time reader that I"ll hook up and drive around with to see if anything is amiss, and I"ll post the results up here afterwards.

Chip-

[Darius]

Maybe one of the coils does not make good contact? But then you should see engine check light lighting on. Which would mean missfire.

By the way the original BMW spark plugs are the best of all :D

[fcotanis]

Initially I also had the briliant idea of switching to Denso.
Second briliant thought I had was to move on to an equivalent single electrode NGK. Somewhat better but still ...a "briliant" idea.

Finally I paused to do more research and put the OE plugs back in and never looked back since.

Darius - the OE plugs are NGK laser cut spark plugs. They are not BMW manufactured plugs.

The concept is simple after it is understood - the coils on this vehicle give a pretty powerful spark. The 4 electrodes on the 4+1 OE NGKs fire in turns. As one electrode fires it's position and resistive properties change enough that the next electrode will be a better candidate and the spark will choose it by virtue of better conditions. Even wear across all electrodes.

If you will observe the OE plugs there is no metal to metal gap but rather a metal to plastic insulator gap. The spark will lick the insulator and reach the center electrode keeping itself clean.

Also the OE plugs make it such that the explosion is free to travel straight towards the piston head without any center electrode to go around like in Densos case.

The whole process is thought out so well that when you think about it - trying to improve on it can only make it worse. The only improvement is to order a new set of OE from NGK so you can save some $$ by not going to the dealer.

So do yourself a favour and throw out those Densos - clean em and return em if you can.

Oh - one last detail - the oe NGKs are designed for a 100Kmiles lifespan. So 30K is just a warmup for them. I'd give them at least 50K or untill you start feeling something. And most likely at 30K if you have not done a carbon cleanup - that's what you are feeling. So take your fuel rail cover off, pull your intake air temperature sensor straight out from the top middle of yoru intake, spray some carbon cleaner in there (like a whole can worth of it - don't forget to spray the sensor too to clean it up). Let it sit for 10-15 minutes and start her up while keeping her floored. She'll start rough - very rough and you will need to keep her floored. And you will see a HUGE cloud of white smoke behind you - burning carbon baby!
Filip

[morcheeba]

carguy-

I'm talking totally out of my rear oriface, but an idea: doesn't the ess supercharger ship with a different temperature plug? Did you use the oem temperature of the temperature the supercharger mfg recomended?

I forget what the temperature rating does, but it's a idea (poorly researched at that!)

[carguy84]

Wow, thanks for all the info!!!

well, I still have the OEM ones that I can put back in, but since they I'd have to do the swap, I'd just spend the money and get new ones. I don't have an air intake temp in my manifold anymore as with the ESS kit it gets relocated and isn't used anymore for whatever reason :?

As for the colder plug, I thought the install called for them, but couldn't confirm it. I bought the kit used, so I don't know which I am supposed to be using. I will hold off from buying any more plugs until I find out what the correct temperature is. I'm sure I can find the info online about what you want to go to a colder temp and what that all means, but I'm guess it has something to do with when it sparks in relation to timing? :? :shock: :?

Damn....and I thought I did my homework when I dedicded to get new plugs :( I changed them at 30,000 because I figured the life of them would be shorter with the blower and the fact it was running a tiny lean in the beginning.

Thanks again for the info and future info!!

Chip-

[Darius]

Chip,

There is no need for colder plug with the ESS supercharger unless you live somwhere on the desert. There are no colder plugs provided with the kit either.

Filip,

Thanks for clarifying the" BMW plug". I couldn't remember the NGK name and I just changed my plugs a month ago. I bought the damn plugs from the dealer. Big mistake they are too expensive there.