Jerking and Check Engine Light Under Boost - Dry Rotted Intercooler Hoses Causing Fuel Cut

Turbointermediate✓ OP Confirmed

Problem

Stock turbo 1989 7MGTE would jerk/buck and flash the check engine light when the turbo spooled up at around 4 psi. The car drove normally in naturally aspirated conditions but would repeatedly cut out under boost. A nasty smell was also present in the cabin. Diagnostic code 34 (turbocharging pressure) was stored.

Car jerks/bucks when turbo boost comes in around 4 psiCheck engine light flashes under boost, turns off when throttle is releasedDiagnostic code 34 stored (turbocharging pressure)Car drives normally without using turboNasty smell in cabinJerking back and forth while driving

Root Cause

All intercooler piping hoses were dry rotted and cracked, causing massive boost leaks. The air leaks in the intake tract caused a lean spike under boost, triggering the ECU's fuel cut protection (code 34). A cracked hose behind the air intake plenum (possibly the brake booster vacuum hose) was also found with tape around it.

Confidence

High confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted November 2019 on SupraForums.com