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Thread: Spark Plugs Denso Iridium

  1. #1

    Spark Plugs Denso Iridium

    I broke down an bought the Denso Iridium spark plugs last week at $12 a plug from Auto Zone.

    I got the IK20 for the first plug that fires and the IK16 (reccommend plug for 1999,C280) for the 2nd plug in the cylinder head.

    12 plug total.

    The plugs have very fine wire tips and are well made.

    They work real well in the motor. Very smooth idle and better pickup on the gas. No noticable increase in power in the upper part of rpm band, but I think they have improved midrange power to some degree.

    The plugs I removed were Champion Plats and were 1 year old.

    Overall the price is high, but they do smooth out the motor and make it pull harder in the middle.

    Jeff
    1999 C43 Obsidian Black; Penske Remote Adjustable Shocks; Adjustable Spring Perches; SSR Comp Wheels, 9.5 & 9.5x17\"; Custom 31.75mm front & 19mm rear swaybar; Ported Manifold; Limited Slip Differential, Headers and race Cats, Other Stuff

  2. #2
    OG Moderator
    Join Date
    Dec 2002
    Posts
    249
    i was lead to believe that the biggest benefit of these plugs would be throttle response. any noticeable improvement in that area?

  3. #3
    The throttle response is much better and again most noticable in the midrange from 3000 rpm to 4500 rpm.

    The car just feels a little snappier and pulls harder.

    My rolling speed run that I do everyday on my way to work showed about 2 mph increase in speed. From my normal of 102 mph to approx. 104 mph.

    Based on this I would say there is some increase in power.

    Jeff
    1999 C43 Obsidian Black; Penske Remote Adjustable Shocks; Adjustable Spring Perches; SSR Comp Wheels, 9.5 & 9.5x17\"; Custom 31.75mm front & 19mm rear swaybar; Ported Manifold; Limited Slip Differential, Headers and race Cats, Other Stuff

  4. #4
    Senior Member
    Join Date
    Jan 2003
    Posts
    207
    My C36 just got new plugs @ 42K miles. It was running like dog-do before the dealer found what was wrong. I heard that C280's sometimes got wrong plugs from the factory. They were to hot of a plug & they would crack causing misfire conditions? True? How many plugs are on the I6 motors? 6 or 12?

  5. #5
    Junior Member
    Join Date
    Jan 2003
    Posts
    8
    the i6 M104 has 6 plugs. when I got a tuneup, I first went with Bosch Platnum +4 but the car didn't feel right. So I took those out and swapped them for the original Bosch Supers. 99cents each. I may try Denso Iridiums since Speedy got good results from them.

  6. #6
    I should have mentioned that my friend put a set of Denso Iridium's in his 2001, BMW 325i and he got very similar results in his car.

    Better response in the low and midrange and a snappier motor. He feels that they are worth the price based on the improved performance.

    Jeff
    1999 C43 Obsidian Black; Penske Remote Adjustable Shocks; Adjustable Spring Perches; SSR Comp Wheels, 9.5 & 9.5x17\"; Custom 31.75mm front & 19mm rear swaybar; Ported Manifold; Limited Slip Differential, Headers and race Cats, Other Stuff

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