Make: Chevy
Model: Cobalt LS
Year: 2005
Mileage: 120000
So I’m having this problem with my engine stalling at low RPM. The RPM goes to 0 and the engine shuts off.
This only happens when travelling at low speeds (e.g. slowly accelerating from a stop, braking, moving in stop and go traffic)
This NEVER happens when I’m travelling above 10 mph (e.g. if I’m coasting at 40 and let my foot off the gas, the RPM can go to 500 RPM but it will never stall in this case).
After the stall, I can always put the car in park, turn the ignition and it will turn back on again.
I have not noticed any electrical problems that occur when this happens (the radio stays on during the stall and the lights don’t dim).
My car was part of that Chevy ignition switch recall, but I took it to the dealership which (hopefully) repaired it.
It sounds like it is stalling out, the engine is just getting loaded in those condiitions enough it can’t keep running. Maybe the idle speed is just too low to begin with, so doing what knfen suggests above is a good place to start. Measuring the current idle speed would make sense too, comparing it to the car’s spec, if you have that ability. Idle quality is affected by air/fuel mixture much more than the mixture’s effect when driving at speed, so you may have a problem with the mixture too. Probably a little too lean. Either a little too much air getting into the engine, or not enough gas. Check for vacuum leaks, maybe try on the next refill try a tank amended w/ a dose of injector cleaning treatment.
Deferred basic maintainance is a common cause for this symptom too. Any spark plugs, engine air filter, fuel filter, ignition components past due for maintenance?
I agree with throttle body dirty. Possibly your IAC too. Had a similar problem a week ago and replaced the IAC. 15 minutes, $40 and the car runs perfect again.