Hey y'all! Weird thing happening with my turbo NB1 '99... Nothing about the tune, nothing mechanical has changed inbetween this problem not happening, and it starting to happen.

I let off throttle and it goes way rich for a second (often backfiring sometimes stumbling) instead of going lean like it used to for decel. WOT is happy, idle is happy, just low RPM cruise and throttle lift causing me issues.

Only a few thousand miles on plugs, wires, timing belt job. Just sanded and tightened grounds, put in new main relay, checked alternator belt. All good there.

Thanks!

 

Check for vacuum leaks, if injectors aren't going into overrun the ecu might not be seeing enough vacuum to trigger that condition. In my case the vacuum leak was on my FPR/MAP line which also caused stumbling and richness

 

I will check over, but they do go into overrun, they just go into over run like a literal .5 second later than they used to (going mega rich for that half second first).