Question about 1997 Mercury Cougar XR7
Engine won't idle, but w/ air conditioner on, it idles fine. What could be the problem?
Usually with the AC on, the idle will slow down, but your case, maybe you set the idle too fast, try set your idle slow down a little bit see if it is working.
Posted on Jul 06, 2008
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FORD IDLE AIR BYPASS
Ford doesn't use idle air bypass to regulate idle speed on its older throttle body (CFI) applications, but uses a solenoid or vacuum diaphragm instead to open the throttle linkage. Idle air bypass is used only on multipoint injection applications. On older pre-OBD II cars, codes 12, 13, 16, 17 & 19 all indicate idle speed is out of spec (too high or too low). Codes 47 and 48 indicate a fuel mixture problem which could be caused by an air leak. On OBD II vehicles (1996 & newer), codes P505 to P509 indicate a fault with the idle speed control system.
The diagnostic procedure when any of these codes are found is to turn the engine off, unplug the ISC bypass air solenoid connector, then restart the engine to see if the idle rpm drops (it should if the ISC solenoid is working). No change would indicate a problem in the motor or wiring.
The ISC solenoid can be checked by measuring its resistance. With the positive lead of a digital volt/ohm meter on the VPWR pin and the negative lead on the ISC pin, measure the resistance of the solenoid. On many applications, the spec calls for 7.0 to 13.0 ohms. If it is out of specs, the ISC solenoid is bad. Also check for shorts between both ISC solenoid terminals and the case.
If the ISC checks out okay, check for battery voltage between the ISC connector terminals while the key is on. Voltage should also vary when the engine is running. No voltage indicates a wiring or computer problem.
Jul 03, 2009 | 1997 Mercury Cougar XR7
Oct 22, 2008 | 1997 Mercury Cougar XR7
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