EGR Backpressure Transducer: Description and Operation

On 2.2L/4-133 non-turbocharged models, the EGR back pressure variable transducer modulates EGR vacuum so the amount of gas flow is proportional to throttle opening. It does this by sensing exhaust back pressure and bleeding off some of the vacuum when back pressure is low. Since exhaust pressure depends on engine load, it is the equivalent of a throttle opening signal. The EGR back pressure variable transducer is located just below the EGR valve.