Jb4, Fmic, cp/bov, dci, downpipes, all new vacuum lines.
MISFIRE happened right after the downpipe install and they were correctly / professionally installed.
Car is misfiring and has rough idle still,
had two different shops check it out.. they tested all sensors, coils, plugs, injectors, checked for vacuum leaks, even changed the valve cover and pcv valve/ hose, and they all were working like they should but the car is running rich/lean still and the spark plugs in cylinders 1-3 are turning black.
They completely removed the JB4 and the car was still misfiring but sounded like it was running better, with the JB4 on it would sound worse and run fine for a minute or two but then the SES comes on and it runs like shit.
The last shop doesn't feel comfortable working on it anymore because they think it's a DME issue or just needs a proper dyno & tune, any suggestions ?? What do you guys think?
Btw the shops I took it too were certified to work on Mercedes, BMW, Audi, VW, etc