1JZ Full Lean Under Boost - Failing Fuel Pump and Cracked Coilpacks

Fuel Systemintermediate✓ OP Confirmed

Problem

1JZ non-VVTi engine runs fine at idle and cruise (14.7 AFR) but goes full lean immediately under any boost, causing severe bogging, misfires, and total loss of power. Even a brief half-second WOT application causes the wideband to read full lean.

Full lean AFR reading under any boostMisfires under boostSevere bogging and loss of power when boost comes onNormal 14.7 AFR at idle and cruiseDark brown liquid coming out of fuel filterLean condition worsens with increasing throttle

Root Cause

Dying fuel pump unable to supply adequate fuel volume under boost demand. Contributing factors included cracked ignition coilpacks (4 of 6 cracked) and a clogged fuel filter with dark brown contaminated fuel.

Confidence

High confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted April 2015 on SupraForums.com