Spark plug AC DELCO or OEM Volkswagen

I’ve had an APR stage 1 ECU tune on my 2017 GTI since 2020 with zero issues. I don’t track it. Just change plugs every 20k miles and have VW use OEM plugs.

Believe it or not I got the Genuine AC Delco iridiums from Home Depot for $3 a plug.

I changed the spark plugs in my nieces 2.5L VW Jetta because it was idling at 1300rpm. Rock solid idle at 700rpm afterwards. Easy way to save some gas.

Changing the spark plugs, spark plug wires, ignition coil and the coolant temperature sensor fixed the cold start issue.

Problem solved: I got a internally bad ac delco spark plug. Gap and everything was correct no cracks I could see literally just a bad plug.

These are OEM plugs without the VW branding so cheaper, I run these in my stage 1 Mk7 GTi and they are good just need to gap them down quite a bit as out the box they are I think .32? I change them every 15,000km or every 2nd oil change

I recommend nothing with platinum. I've had problems with those in my 1980 gbody with a 305. I just keep it simple with old ac/delcos now. Keep it simple for less problems.

Problem solved: I got a internally bad ac delco spark plug. Gap and everything was correct no cracks I could see literally just a bad plug.

Hope you screwed them in with the correct torque, unlike my VW dealer. They started to unscrew themselves and causing instant misfire and rpm drops to 200 and engine shutoff.

I bought eight new AC/Delco from eBay. While gapping the plugs, I noticed that in two of them, the ceramic was not concentric with the body of the plug. It's difficult to measure, but it's easy to see by eye. I'd estimate the error is about 0.02 to 0.03 inches.