Help! ccasional puff of black smoke

[TAI1FOB]

hi all,
I've been having black smoke coming out of my tailpipe for the last few summers, and here are the symptoms.
I would be crusing for awhile at 40ish on freeway, and when i want to accelerate in D, right before boost and down shift, a metallic rattle sound is heard from the exhaust pipe, then follows with a big puff of black smoke.

I've changed spark plug to the latest NGK version, and replaced all coilpacks. symptom improved when they were first installed, but now it's coming back after a year or so.

anything else I should look into? thanks for the help.

 

[TAI1FOB]

problem solved with a MAF sensor replacement.

 

[FMX_DBC]

problem solved with a MAF sensor replacement.

What did the new sensor cost you? Was it throwing any codes before?

 

[Slothy]

Thanks for following up with the fix. No complaints here even if the thread is old.

 

[TAI1FOB]

What did the new sensor cost you? Was it throwing any codes before?

wasn't throwing any code, that's why it was so hard to diagnose. I found some HITACHI sensor on Ebay for 105 shipped. the part arrived with VW part number scratched off, but official HITACHI rep gauranteed that those parts are legit.