i recently bought this vw jetta and within a month it blew the mass airflow metter. i noticed that the car was throwing black smoke out of the exhaust. i took it to a shop and the replaced the metter the said it was running lean. the car still does it but it only does it when its on idle and i rev the engine. i replaced spark plugs and wire but no luck. any idea wat might be wrong.
There are 2 O2 sensors. 1 precat and 1 after cat. Pre cat sensor usually fails. Also cat maybe clogged. Rattle could be from inside cat or just heat shield. Get a hi flow cat and replace front O2 sensor and should clear up issue.
02 Jetta GLX VR6 12v
1 of those stubby things on the roof
Unitronic stage 1+
2.5 in borla catback w/o resonator
2 12" JL W1v2
JL A1200 Amp
well i dont have any check engine lites on or anything
Hey dude i had this happen to me on my car, i changed the cat/spark plugs and plugs/changed the oil but nothing fixed it untell i changed my first O2 sensor replace that and it should work, it wont work right away but it will clear ur black smoke and will run normal and as for your cat ratteling then its from the in side of the cat, the filter in the cat has burnt and it shakes in side the cat if ur car has under 160000km then u should b e still coverd under a recall warrentee take it to a vw dealer if ur car has less then 160km and u should get a free replacement
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