Hi Guys, Just signed up on this site and was wondering about spark plugs. I have an 05 sierra z71 and was thinking about putting some e3 spark plugs in. ...

Hi Guys,

Just signed up on this site and was wondering about spark plugs. I have an 05 sierra z71 and was thinking about putting some e3 spark plugs in. Has anyone ran them in their truck and noticed a difference?

fyi Your GMC comes factory fitted with AC Delco Iridium spark plugs.

I have not personally used the E3 plugs, but have read many reviews. Most usually end with the owner changing out the plugs within a few thousand miles. Not good plugs for our engines. Stick with the AC Delco iridium.

The AC Delco iridium plugs should last you over a 100,000 miles. If not, you can always get them replaced with the warranty.

ok, thanks for your input. I got both sets and tried the E3s first just out of curiosity. They have a 1 year warranty so I can replace them for free if anything happens. I also purchased some 8 AC Delco iridium replacements just in case. I was curious because of all of the reviews about these E3 plugs. If i'm not happy with them after 1000 miles, i'll change them out. using second trip odometer to track mileage on them. So far, I noticed a significant power increase and gas mileage increased as well. Very happy at the moment with their performance but may end up going back to the ac delco's since i will not have to change them for at least 100,000 miles.

I ran the E3's in my 4.3L for approximately 20,000 miles. They did give more and increased mpg's. After about the 20,000 miles mentioned they started misfiring. I'm back to AC/Delco's and happy with them. Keep us posted on how thing work out for you.

I will. So far I am very impressed with their performance. I think they are designed to be switched out every year when you do annual maintenance. Right now i'm at 500 miles and they run great. at the first sign of power loss I will post the actual mileage from the trip odometer for everyone to see and what to expect on life expectancy. They definitely not a 100,000 mile plug but I do want to see how long they last.

Here is an update on the E3 plugs in my truck. So far mileage is up to 4687 miles on these plugs and they are still running strong. no signs of misfire or power decrease. Will continue using them at this time. using trip odometer to track progress. Extremely aggressive take off from stopped position, acceleration on hwy is 4.5 seconds from 65mph to 90 mph. That was a current endurance test after mileage stated above.

Will let you guys know when I notice the plugs are done and what the ending mileage is. So far, These plugs are everything the reviews say they are.

Hope this helps.

I worked in Spark Plug Engineering at GM. I can tell you that the E3 is not a plug I would put in any engine. I'm happy that you are happy Mr. pblakey. Time will tell. A little history for you and others.
In the early 90's, AC Spark plug created the rapidfire spark plug line. Basically all we did was create a product that had a bunch of sharp edges on both electrodes (great for spark transfer but short on life) and the product protruded about 1MM into the cylinder which gave you a little spark advance. Those plugs were intended for the old design of engines that always used the safe mode for their calibration. They NEVER were installed as OEM product on any engine. Did they help some of those older design engines run better? Yes, for about 12,000 miles. Then later they went to a platinum model.
The 4.8 and 5.3 engines of today, FAR exceed the designs of earlier engines and that required a MUCH more durable spark plug. So, in my opinion, putting an E3 plug in any of the newer engines is basically going backwards. E3 is nothing more than smoke and mirrors. You can believe what you want.

I would stick with the ones that came with the truck, AC delco.