QuestionThe vehicle is a 2000 Toyota Camry CE 2.2L. After a failed emissions test I was told it was insufficient EGR flow and after scanning to confirm I replaced the EGR valve and the EGR modulator. After rebooting the computer and after 30-40 miles the check engine light is back on.
What am I missing. This is not a CA car. Thanks !
AnswerClyde,
Toyota's EGR system is a bit more complicated than others. Fist, check the vacuum lines from the throttle body to the modulator. The tubes clog up with carbon and also clean the throttle bore where they enter. These ports should only have vacuum above idle.
Second, check your exhaust line on the bottom of the modulator to see that it is flowing exhaust to the modulator.
Third use a vacuum gage on the output of the modulator and verify vacuum above idle. It doesn't build much. Around 5 inches. If that looks good, some cars use a VSV (Vacuum Switching Valve) controlled by the computer to stop EGR operation. Follow the lines looking for breaks. You can jump power and ground to the coil on the VSV and verify it conducts vacuum. Also, make sure the EGR valve is on the vented side of that valve or it will get stuck open.
Last, if you know the valve is opening and the engine runs rough indicating EGR flow then test the temp sensor in the EGR tube or valve base. Toyota looks for a change it temp after commanding the valve to open. It is a simple resistor type thermistor. The voltage will go down as it heats up.
Whew, I know that is a lot to think about in one setting so if you need any additional help let me know.
