7MGE High Idle After Warming Up - Faulty TPS Replacement and Calibration

Engineintermediate✓ OP Confirmed

Problem

7MGE engine idles normally at 700-800 RPM on cold start, but after driving the idle stays elevated at 1.2k-1.3k RPM and will not return to normal. After valve cover gasket replacement, idle worsened to 1.5k RPM. Disconnecting TPS did not cause engine to bog, suggesting the TPS idle contact was not functioning correctly. OBD1 connector was not flashing any check engine codes despite a fault being present.

Cold start idle normal at 700-800 RPMIdle stays at 1.2k-1.3k RPM after driving/warming upIdle worsened to 1.5k RPM after valve cover gasket replacementDisconnecting TPS did not cause engine to bog outNo check engine light despite faulty sensorEGR vacuum regulator also found leaking smoke during diagnostics (secondary issue)

Root Cause

Faulty Throttle Position Sensor (TPS) was not properly signaling the idle contact position to the ECU, causing the ECU to maintain a higher-than-normal idle speed. The OBD1 diagnostic system was also not reporting the code because the W terminal on the ECU needed to be grounded to enable check engine light output.

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted April 2025 on SupraForums.com