Autolite Spark Plugs

[Vibraphone]

Removed 4 AUTOLITE XP #3924 Iridium plugs from the 2006 Vibe today. I’m 2nd owner. First owner: 183K miles. Me: 1.5K miles. It just didn’t run, idle or accelerate smoothly. At first I thought it was the belt tensioner, but that was okay (have documentation new belt>2017).

A tank of Shell Shell V-Power premium gas + 2 cans of Liqui Moly Jectron made a noticeable difference, but still lumpy idle + uneven + ‘boggy’ acceleration, esp at low/mid RPM: 800 to 2000

The plugs came out with the strength of a god. Very dry threads. Very overtightened. Evidentially installed by someone who thought Spark Plugs were the same as Lug Nuts.

Good news: All 4 AUTOLITE plugs looked even. No oil. But gaps were all different--very wide – compared to the new BOSCH #9603 Double Iridium plugs I was installing. I didn’t have a gauge, but visually with a 4X loupe, the Autolite electrodes were dark brown + worn down to about half the size of the new BOSCH plugs. Compared to the new BOSCH plugs the AUTOLITE electrodes looked very worn out—in my experience, too worn out to use.

I have no records how long these AUTOLITE XP’s were in this 2006 Vibe, but it couldn’t have been that long, as AUTOLITE XP #9324 Iridium plugs are only about 10yrs old. This is a pretty poor testament to AUTOLITE.

New BOSCH #9603 Double Iridium plugs made a huge difference. With oil on the threads, they installed fine. The car idles smoother, has much better throttle response and drives smoother—esp from idle up to mid-RPM’s.

NOTE: I also replaced the 4 orig (2006) coils with a new set of OEM dealer coils I got a good price on. They may have played a minor role, but likely the OEM 17yr old coils would have performed the same.

[SeattleJeremy]

Dry threads is great! Make sure to torque them to spec 12.5 Ft/LBS

[Mark]

NGK or Denso only for my Vibes.

[SSizler]

NGK or Denso only for my Vibes.

This, but reverse order for me.
Denso first choice.
Also, the Denso plug threads are pre-lubed, so the head threads should be clean and dry for proper torque.

[tpollauf]

NGK or Denso only for my Vibes.

x2

[VibeNation2024]

I went with Bosch double iridium (9600) and Denso when I did a tune up a few years ago.