Spark plug Bosch or Denso

Also, did you even replace the spark plugs with Denso IKH24's? Probably not and that is REQUIRED in order to run correctly.

On 02/18/2016 I switched the plugs with the Denso IKH22 at 15800miles. Jetta is more rev happy. No slow down throughout rev range, and no more pause hesitation between 3.8k-4k RPM. Just pulls, and pulls even harder. Also idle very smoothly.

I switched to the Ikh24 and it really smoothed the car out.

Replaced my OEMs this summer to Denso K16GPR-U11 and has been getting really good mileage and smooth idling since then. Now planning to try NGKs next time.

Belated follow up. I replaced the plug at the distributer as the signal from the hall sender was intermittent. Brand new Bosch plugs were had for cheap.

So I grab a new ignition coil, and a full set (4) of spark plugs. The Pre-gapped BOSCH Iridium plugs were the same price as OEM platinum, so I figured that's fine for me.

After pulling the plugs, Cylinder 1 plug was definitely eroded. The other 3 plugs looked fine, but I might as well replace the lot. The new Ignition Coil went into Cylinder 1 as well, and I started it up.

Check engine light went off, starts up fine, drives fine, idles fine.

Yeah, I'd rather use some cheap BOSCH SUPERS or other $2 copper plug than any Autolite.

I'm using the OEM Bosch spark plug. I gapped mine to 0.024" as per Bentley and the car seems to run fine.

First step, get those Bosch Platinums to a trash can where they belong. Even when I was in Bosch Fuel Injection Training School back in the early 90's, the Bosch Instructors were telling us not to put them in anything unless we wanted to start chasing driveability issues.

I'm a technition with many years under my belt.... and had numerouse out of the box brand new BOSH plugs that upon installing them were dead, not just one but two in the same set, i would then take em out, check gap, and spark test the plug wires and coil, swop them to a diff cylender and bam.. still crap, im not trying to knock them and im not and NGP rep, im speaking from experience