Using a 3-way connector, connect a vacuum gauge to EGR vacuum hose. Start engine and run at idle speed.
With coolant temperature below 106°F (41°C) on Starlet or 122°F (50°C) on Tercel, vacuum gauge should indicate zero at 2000 RPM on Starlet or 2500 RPM on Tercel. When engine is warm, low vacuum should be present.
Disconnect vacuum hose from EGR vacuum modulator port "R". Using a jumper hose, connect port "R" to intake manifold vacuum. Vacuum gauge should indicate high vacuum at 2000 RPM on Starlet or 2500 RPM on Tercel.
NOTE: Engine will misfire slightly at this time, as a large amount of EGR gas enters.
On Tercel, disconnect and plug vacuum hose from port "S" of EGR vacuum modulator. Using a jumper hose, connect port "S" to intake manifold vacuum. Vacuum gauge should indicate low vacuum at 2500 RPM.
On all models, remove gauge and reconnect hoses. If system performed as described, it is operating correctly. If not, test individual components and repair or replace as necessary.

Fig 1: Starlet EGR System

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Starlet & Tercel