brandonppr

iTrader: (9)

I have a 98 Z a4 ms3 heads headers 3500stall solidmotormounts !cats 3"truedueldynomaxracemufflers

I have dtc p0481 and p0507 I am getting some knock retard

jimmyblue

iTrader: (11)

'98s have a known knock sensor problem, have
you replaced yours with the part type that
supersedes them, '99-up?

Your two codes are cooling fan 2/3 relay and
idle speed high. The fans might make for some
hot-weather, after-high-load ping but I doubt
the idle speed has to do with anything. Though
with the mod list and mystery tune, who knows
what non-code-setting mixture / spark influence
might be present?

sonicbaloo

iTrader: (2)

The P0507 is more than likely caused by too big of a hole being drilled in the TB and the idle hanging high. If not, then have the car re-tuned.

Chad