Reader Question

Hey, So I got my car, (Subaru Impreza 2000 RS 2.5) and its has a pulsing Idle. I start my car cold, idles around 500 rpms (the normal) then once the car is warm, its starts to pulse. Always goes lower in rpms then corrects itself back to 500. But in the correction it never fully corrects itself so its always decreasing. Then the car dies. Only at stops. the car runs fine when driving. Except acceleration is rough. If I turn on my A/C, it almost keep the car alive. Only when the A/C is increasing the idle does the pulsing go away and no stall occurs. When the A/C is turned off the pulsing come back. On the low end of the pulse the dash lights dim.

I have checked the alternator and the test was positive. Reading around 14.3. I also had replaced the fuel injectors. Cleaned the o2 sensors and IAC valve. Checked the grounds. The wires plugs and coil pack are fairly new 10,000 miles. I have also cleaned the throttle body opening and my cars MAP sensor.

Can you please help me

Hey there,

I would still suspect a dirty throttle body, idle control motor or the base idle speed is set to low. I am not to familiar with your vehicle but I would suspect there is a cleanable idle control motor. I would also make sure there are no vacuum leaks.