the engine to stall and surge at idle
ck for vac.leak or bad iac valve
bad iac valve or vac. leak
Low fuel pressure, bad IAC valve, vacuum leak, bad injector(s). You also need to check the EGR valve.
depends on the year.1996 to 1990,some times its low coolant.the coolant grounds the iac,but they do go bad.
no, that's good. If it doesn't die, then you're in trouble. You need to clean or replace your IAC
the iac is controlled by the computer and adjusts the air flow needed by the engine, hence idle air control. if the iac is defective and does not seat properly, it will cause a high idle
Could be a restricted catalytic converter A restricted cat would cause a loss of power but not the vacuum leak sound. I would look into the Idle Air Control Valve-IAC, battery voltage, and O2 Sensor. The IAC controls the amount of air bypassing the throttle body, though it is likely the IAC is not the real problem. A low battery voltage on starting can cause improper IAC calibration. A bad O2 sensor will also cause problems and turned out to be the problem on my truck.
Hesitation Definition: When the throttle peddle is pressed the engine fails to respond, and may stall. For this to be true it is idling correct. No, a failed, stuck or gummed up IAC will not cause the hesitation. The gummed up may if it has blocked any of the small passages in the throttle body. It is much more likely you have a bad plug, plug wire, Oxygen sensor, Temp sensor, Bad MAP sensor or other problem.
Vacuum leak is one cause. ----- Another possible cause may be a bad Idle Air Control Valve (IAC Valve). Your car should Idle, once the engine is at operating temperature, between 680-750 RPM. If the engine idles below this range with no appliances on, i.e. Air Conditioning, Fan or Window Heat, then your IAC Valve may have gone bad. SUBMITED: Friday, 03JUN11
iac is bad need to be replace
No. Most likely you have a bad IAC (Idle Air Control) on top of the throttle body. A vacuum leak would also cause stalling at a stop light. The IAC looks like a small electric motor held down by 2 bolts that take and 8mm wrench.
Could be you have a bad IAC valve