99 Mustang rough idle
fundilly
03-15-2005, 05:35 PM
Mustang V-6 idles smooth as silk with the A/C on but as soon as it is off the engine runs rough and misses. Any Ideas???? I have tried plugs, reset computer, wires, etc.
LI-SVT
03-16-2005, 02:17 PM
What rpm is the idle with the A/C on?
What rpm is the idle with the A/C off?
It may be the IAC valve.
What rpm is the idle with the A/C off?
It may be the IAC valve.
fundilly
03-18-2005, 11:40 AM
The Mustang idles at 750 RPMS with the AC off and continually misses. As soon as the AC is turned on it continues to run at 750 RPMS but the motor runs as smooth as new.
LI-SVT
03-21-2005, 08:48 AM
It still could be the IAC. With the A/C on the valve is in a different position (more open) to maintain the 750 RPM. Yours may be partly clogged causing the engine to starve for air without the A/C on. Otherwise I am stumped.
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