My '07 LT has 82,000 miles on it, and it's starting to feel a little sluggish. I think it's about time for some new plugs. Has anyone had any luck with aftermarkets or should I just stick with OEM?

 

OEM (Iridium AC Delco)... I tried Iridium Bosch & Autolite. Money wasted.

 

OEM only, too many have tried others only to have issues, our engines seem to like the Delco plugs best so why mess around experimenting.

 

I bought the E3 plugs had it scanned and had 20,000 missfires so I bought new AC Delco Ird.

 

What issues? Please explain what the problems are, don't just say there have been issues. I have not had any problems using Bosch or Autolite, Iridium or Platinum.

In days of yore you did have to worry about if the threads were SAE or Metric, but now I think they are close enough if not the same. Or, you could go with a brand from a metric country, if that bothers you still. As far as I can tell the EcoTec is all metric.

 

And the results of the new scan are...? How can one say one is better than the other without a comparative test?

 

Then you are a lucky guy Don. I had error code P1174 (lean mixture) after 4,000 milles with the bosch Iridium 4 electrodes, and 2,500 milles with Autolite Iridium too. Also these lead to have carbon deposits and worn electrodes (Longer gap). I back to the Autolite and no issues since 1 year ago.

 

I really never heard anything good about switching from OEM.

 

Longer gap? Is that a translation problem, or do you not set the gap when you install/tune. I have not found the gap out of the box to be wrong very often, but no guarantee. I generally replace mine around 75,000 miles, or when my mpg goes down a bit. The book says 100,000.

Having said that, you seem to be describing a problem other than brand of plugs. Like Oxy sensor, fuel pump injector, head gasket, funny gas, loose /bad connection to the plug are a few. But you seem to have fixed it so, no argument.

FWIW, a friend of mine spent a year and many dollars on P1174, would you believe it was the fuel pump?

 

I suppose I should have elaborated on the issues like misfires, code setting, premature plug failure, performance decreases, and the like. I think you'll find that the people here who have gone away from the AC plugs come right back to them in a hurry, it seems that the Ecotec engine regardless of the vehicle its used in, just works best with the plugs designed for it.

As far as the plug gap goes, the AC plugs are pre-gapped at 0.042 inch (1.06 mm), you can check them of course but I've never run across any that were out of spec. On the other hand, Bosch plugs are the worst offenders and I'm not sure if its QC or something that happens in transit.