Intake Valve cleaning on 2011 Tiguan

I would try some fuel system additives before spending that level of money on dubious claims from dealers looking to cash in. Try LiquiMoly Valve Clean or Techron. I have not used the LiquiMoly but their other products are great.

I would also pull the plugs to look for clues as to why the engine is misfiring.

I spent countless hours looking for answers on the web. I read that gas or engine additives will not clean the intake valves of DI engines. The plugs are also pre-gapped so no adjustments are needed. I have also read that intakes valves are in need of good cleaning at about 70,000 miles. I saw many users on Youtube used seafoam to clean but I also heard scary stories of malfunctioning afterward so scared to use it. I would like to hear from someone who had similar problem and solved it. Thanks for reading.

Ah.. what? I installed NGK spark plugs and Denso coils. Per the reviews, Denso was better than OEM. The funny thing is all worked well for last 6 months so I don't think I installed them incorrectly. Chicago weather is another reason I have rough idle for first 5 min and smooth ride after the engine reaches normal temp. Should I wail out til spring and see what happens?

Have the dealer inspect the high pressure fuel pump lifter. Mine went out on my Jetta and led to reduced performance (similar engine). This will improve performance back to original and ensure great performance for another 70k miles.