Spark Plugs
TReK
Joined: Sep 2020
Posts: 2,979
Likes: 759
From: British Columbia Canada
Externet, I’m actually quite surprised to hear that. In my opinion, spark plugs are a relatively cheap preventative maintenance item that are really easy to replace. Due to the location of the original coil packs, the wires are considerably more difficult (more time consuming than difficult) to replace, but plugs are very easy on the D2.
4wd Low
Joined: Jan 2025
Posts: 10
Likes: 4
From: Texas
Spark plugs should generally be replaced every 30,000 to 60,000 miles, but it can depend on how the vehicle is driven and the specific type of spark plugs being used. NGK is a highly recommended brand for the D2. Their iridium plugs are known for their durability, better fuel efficiency, and smooth engine performance. They can last a bit longer than standard copper plugs, often around 60,000 to 100,000 miles. If you’re looking for spark plugs, It’s definitely a good idea to reach out to partmasterhub auto parts shop; they were very helpful and provided answers to all my questions.
Recovery Vehicle
Joined: Jul 2012
Posts: 984
Likes: 156
From: Mideast US
How to test a spark plug as to determine how much has degraded or improved since new condition and what are the parameters measured under test ? 
Last edited by Externet; Feb 12, 2025 at 02:53 PM.
I've used NGK Platinum & Iridium plugs in my D2's with fantastic results mileage wise. I for sure usually get 50/60K out of them no question. For the people using Copper plugs in a D2 sure they will work, but the D2 setup takes advantage of Platinum/Double Platinum/Iridium plugs. Copper will work, but get you much less mileage out of a set. My 97 D1 GEMS setup has a set of NGK Iridium plugs in it from the previous owner (noticed them when I did a HG shortly after buying it). That D1 gets 300 miles to a tank so I'm just gonna leave it alone 
Camel Trophy
Joined: Dec 2009
Posts: 3,893
Likes: 958
From: Charlotte
Here's what I wrote in another spark plug thread a couple years ago, pointing to why copper plugs aren't a good idea in a DII.
"The most important consideration for spark plugs is that they are double-platinum, or double some other precious metal (often iridium).
The reason is that the DII uses a wasted spark ignition system. Google it. Conventional copper plugs wear out quickly if used in a wasted spark system.
Before I started taking care of my truck myself, a local shop installed conventional copper plugs. They lasted just 13,000 miles before the misfires appeared. I replaced them with the OEM Champion 7070s (RC11 PYP B4). They are double-platinum, and were still going strong 72,000 miles later when I replaced them proactively only because I was replacing the wires.
There is a lot of snake oil marketing with spark plugs. On top of that there are heat range specifications to be considered. Other brands that are double-platinum and in the correct heat range may work equally well in your DII, but the 7070s are specified and proven."
The reason is that the DII uses a wasted spark ignition system. Google it. Conventional copper plugs wear out quickly if used in a wasted spark system.
Before I started taking care of my truck myself, a local shop installed conventional copper plugs. They lasted just 13,000 miles before the misfires appeared. I replaced them with the OEM Champion 7070s (RC11 PYP B4). They are double-platinum, and were still going strong 72,000 miles later when I replaced them proactively only because I was replacing the wires.
There is a lot of snake oil marketing with spark plugs. On top of that there are heat range specifications to be considered. Other brands that are double-platinum and in the correct heat range may work equally well in your DII, but the 7070s are specified and proven."
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