EGR System
- Check and clean vacuum modulator filters with compressed air before proceeding with test. Disconnect vacuum hose from EGR valve and, using a "T" connector, connect a vacuum gauge. Check that engine starts and runs at idle.
- Check TVSV with coolant temperature below 122°F (50°C). Check that vacuum gauge indicates zero at 3000 RPM.
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- Check TVSV and EGR vacuum modulator with engine hot. Vacuum gauge should indicate low vacuum at 3000 RPM.
- With engine idling, apply vacuum directly to EGR valve. Engine should run rough or die. Remove vacuum and reconnect vacuum hoses to proper locations. Engine should run smooth. If no problem is found with this inspection, system is okay.