Drive a 1992 Toyota Camry LE. Car warms up, drive a few miles and it idles rough and has no acceleration. Open hood, unplug vacuum hose to vacuum sensor assembly. Car stalls. Refasten the vacuum hose to assembly. Problem solved. Drive for a few miles and car goes through the same sequence. What is wrong and how can I troubleshoot this problem in order to fix it?
In many older cars, many engine functions are controlled by vacuum. For example, the EGR valve on Camrys are operated by varying vacuum to the valve. You may have a leaking hose that affects the accuracy of the vacuum signal to the parts that cause rough idles, stalls, etc.
Just about all newer cars use electronic control. Like the GM EGR valve from a few decades ago started using stepper motors to control the EGR valve lift. The accelerator pedal on BMWs control the amount of air intake by Continuously Variable Valve Lift -- they use no throttle plates! And yes, Camrys still use good 'ol jack screws to set belt tensions.
In any case you should not disable the control signals by unplugging vacuum lines. Check for vacuum leaks and replace gaskets or bad hoses.
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.