Spark plug Bosch or Motorcraft

Bosch iridiums, these for longevity, copper ones have better spark if your concern is performance

Today I installed new spark plugs and the misfiring situation has improved significantly but is not completely gone. If I pull up the RPM too quickly the misfire counter goes up.

I just replaced my oem densos with some Bosch plugs that were labelled as being pregapped 1.1mm. I wanted them to be 1mm and checked with a gauge and Lo and behold they were already at 1mm. Whacked them in and improved my fuel consumption immediately.

I took it back in after setting the DPR to 2.5± 2.5 mA, checking again for any vacuum leaks, tightening down all the exhaust components, and changing out the spark plugs (again). I also checked the O2 sensor, it was fluctuating between .1v-.7v continuously.

I do run Motorcraft plugs because they seem to crack a little less than the Autolites.

Just got a Jetta again - 2010 Limited Edition just shy of 100K miles and I've got one problem with it. From a cold start, usually in the morning, the 1st 10-15 seconds run rough before settling down to idle.

I have never seen any real large difference in NGK, Denso, and Champion if the proper heat range/type plug was used.

I'm not a fan of the old platinum Bosch design or regular autolite.

I've heard for many decades how bad Bosch spark plugs are and I figured the coils would be just as bad, if not worse.

Bosch spark plugs are junk.

This is why I don't use Bosch plugs. It goes back to the quad fire plugs with a platinum center electrode that would fall out.