7MGE Revs Then Stalls After Rebuild - ISCV Air Hose Leak

Enginebeginner✓ OP Confirmed

Problem

After rebuilding a 7MGE (head gasket, valve stem seals), the engine would crank, rev once, then immediately stall. It would only stay running briefly when manually holding the throttle open, and made a weird screeching noise. Additionally, the check engine light was not working and no diagnostic codes could be read.

Engine cranks, revs once, then immediately stallsWill only stay running momentarily with throttle held open manuallyWeird screeching noise when trying to runCheck engine light not illuminatingNo diagnostic codes readable when jumping T and E1TPS voltage (IDL-E2) static at 4.55V with no change from throttle movement

Root Cause

An air hose connecting the ISCV (Idle Speed Control Valve) to the throttle body had a poor connection and was leaking unmetered air. The vacuum line was connected but the larger hose fitting was not sealed properly, causing a significant air leak that prevented the engine from idling. A secondary issue was a disconnected ECU-area connector (yellow connector above the main ECU connectors) that disabled the check engine light.

Confidence

High confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted June 2022 on SupraForums.com