Popping Noise After 20 Min Driving - Vacuum Leak on 1JZ Swap

Enginebeginner✓ OP Confirmed

Problem

After driving for approximately 20 minutes, a popping-type noise appears from the back/top area of the engine on a 1JZ (JZS171) swap into an MX83 chassis.

Popping noise from rear/top of engine after ~20 minutes of drivingNoise intermittently goes away with revs

Root Cause

A vacuum leak from a disconnected or unrouted vacuum hose at the back of the engine. The hose destination was unclear due to differences between VVTi and non-VVTi 1JZ vacuum line routing.

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted September 2019 on SupraForums.com