I had EPC light/limp mode and P303 as well about a month ago on my '12 GLI (APR Stage 1+) at 102K miles that recently had a walnut blast and new Denso plugs at around 101K miles. Swapped coil packs as well and still P303 with EPC light/limp mode.
I like ac delco. But I recently used denso tt fine wire plugs I two different ls engines. What a difference in power. And gas mileage.
I just replaced mine, at 80k, with Denso PLatinums. The same brand as the stock plugs.
Denso Iridium 1 step colder plugs. Running great on my 2017 Jetta 1.4T
Get the oem denso ones. There is nothing better than oem for that kind of thing.
This is what a 202k mile spark plug looks like on an 2013 Lexus gs350 daily driver. Pretty impressed with it overall. All 6 plugs look exactly like this.
For spark plugs, denso or bust
I've been running Denso (5346) IKH24 Iridium gapped .024 on APR stg1 for 48k miles and most recently on stg 2 with no issues.
Denso TT iridium are so far the best ones I’ve tried in terms of performance
Skip them, they are junk and a waste of money.
Get a good single platinum plug like the Denso 4511.
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