I know I have seen this on one of the forums, but can’t seem to find it in search.
1996 Metro 1.0L runs perfectly, EXCEPT…
Idle surges under electrical load such as blower fan or headlights.
Idle jumps up to 2000 RPM and drops to 1500 Rpm about once a second for 8 or 10 cycles, then returns to normal idle until the throttle is opened even slightly- then repeats. It does this when driving whenever the pedal is slacked off during deceleration, resulting in a rather unnerving pulsation, as if one was tapping on the accelerator pedal.
Troubleshooting charts don’t seem to address this adequately, so if someone can steer me in the right direction I would be very grateful.
TIA
Could be a failing “idle air control” solenoid.
The surges occur when you release the gas pedal and it goes to the idle position? (That’s idle position, NOT idle rpm.)
Check the tps (throttle position sensor) voltage and ohm values at idle position. You, also, need to check the operation of the idle air control valve. The instructions should be in the repair manual.