I changed my iac and the engine is still massivly surging idle
- Thread starter Cherry99GTvert
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wmburns
SN Certified Technician
How to trouble shoot low Idle IAC
Does the idle surge in drive? Neutral? Reverse? Does running the AC make a difference?
Start first by confirming fuse F2.8 in the CJB. Has there been any interruption in electric? Have you noticed the dash do a full sweep on any startup?
Next look for any vacuum leaks. Esp in the IAC bypass line between the intake tube and the IAC itself. Even a tiny leak can cause problems. Don't cut corners here. Change the PCV valve for insurance.
Check the throttle return spring. There should be two. If not, one is broken. Work the throttle back and forth checking for any binding in the linkage.
Clean the MAF. Use only cleaner desinged for the job.
Have you adjusted the throttle body set screw in an attempt to resolve this?
A weak cylinder can cause a slow idle. What is the condition of the plugs? How's the gas mileage? What are the results of a compression test?
Stuck open EGR valve or excessive EGR flow could also cause this symptom.
Do you have an ODB2 scanner that can access live data?
Check out post #3
http://www.stangnet.com/mustang-forums/810729-starts-but-dies-idle-help.html
Does the idle surge in drive? Neutral? Reverse? Does running the AC make a difference?
Start first by confirming fuse F2.8 in the CJB. Has there been any interruption in electric? Have you noticed the dash do a full sweep on any startup?
Next look for any vacuum leaks. Esp in the IAC bypass line between the intake tube and the IAC itself. Even a tiny leak can cause problems. Don't cut corners here. Change the PCV valve for insurance.
Check the throttle return spring. There should be two. If not, one is broken. Work the throttle back and forth checking for any binding in the linkage.
Clean the MAF. Use only cleaner desinged for the job.
Have you adjusted the throttle body set screw in an attempt to resolve this?
A weak cylinder can cause a slow idle. What is the condition of the plugs? How's the gas mileage? What are the results of a compression test?
Stuck open EGR valve or excessive EGR flow could also cause this symptom.
Do you have an ODB2 scanner that can access live data?
Check out post #3
http://www.stangnet.com/mustang-forums/810729-starts-but-dies-idle-help.html
fast97gt
Active Member
did you disconnect the battery during the part change? i thought i used to get junk iac valves but then i disconnected the battery when i replaced the second one i bought it worked, i did the procedure again with the first one and it acted as if nothing were wrong with. so try disconnecting your battery
