2016 1.4 TSI mystery misfire problem
Hello I’ve got a 2016 1.4 with 115k miles on it and it’s having misfires issues. About 2 months ago I got a single cylinder misfire code and took it to an independent shop and they replaced all coils and plugs. Coils are Delphi and plugs are Bosch evo. Recently I’ve noticed the engine has a bit of shaking when cold starting on high rpm’s and goes away after a minute once the engine rpm’s dip down. Never had a problem starting and hasn’t died while driving. I have noticed slightly sluggish acceleration at times and other times it seems oddly jumpy. Fast forward to last week and I got codes for 3 out of 4 cylinder misfires and brought it back to the independent shop. They think it’s either O2 sensors or bad cats. I took it to a VW dealer and they think the car doesn’t like the Delphi coils. From what I’ve read online direct injection engines suffer from carbon buildup but both shops said that wasn’t common for the 1.4. I’m lost at this point and any option is just throwing parts at it and hoping it works for $1k plus whichever way I chose to go. Any insight would greatly be appreciated. Also I’m in southeastern Michigan area if anyone knows a good mechanic that specializes in jettas. Also I do a lot of driving, 600 miles a week with a good 100 miles of that being heavy traffic miles. Oil changed recently and no signs of oil burning. On board MPG hasn’t shown a change in fuel efficiency (40mpg clear highway 35 with traffic).