I have had all the symptoms mentioned on this page. Erratic and hunting idle. Misfiring. Popping in intake tube like popcorn being made. Fluctuating headlights in idle. Sometimes have to start car second time. Idle not coming down properly or taking a long time to come down. Spent hours trying things checking connections and hoses. Nothing found. Ford had it twice in the 3 years we have been having this issue. Also had the bank 1 Autolite platinum spark plugs burned down to the ceramic in less than 2 years! Cant believe the girl was still running with the massive plug gap. Bank 1 plugs were normal looking.
Well folks after 3 years of replacing IAC
, Engine temp sensor, timing chain, plugs, different gaps, coil, wires, blah blah blah and many hours hunting online for an answer I finally found it.
The alternator is regulated by the PCM
Module hence the 3 wire connector. When the board or diodes go defective in the alternator, the PCM
gets a noisy feedback and it does not behave properly and does not control the motor properly. Computers do not like noise or bad signal with AC
waveform. SIMPLE TEST was to unplug the alternator while running and see if the engine runs normal again. For me, as soon as I unplugged the alternator, all the symptoms mentioned above instantly went away. Idle came down more. It smoothed right out. Popping in intake (more noticeable when you undo the air filter connection) completely stopped. I purchased new alternator and installed it. Completely discharged the computer for a few hours to make it a clean start and everything is working awesome.
Better vacuum, better braking, lower idle, more control on slippery ground (I am in Canada in rural area) and wife says it has more pickup, smoother shifting and requires much less pedal so way better driveability. Got a kiss for fixing it too LOL
Hope some of you can benefit from this. Love the Taurus!!!
2006 Taurus OHV
Vulcan 3 litre. 248,000 kilometres (150,000 miles) on this girl.