I posted about this in another thread that could be related, but didn't seem to be getting much action, so I figured I would make it's own thread.
My Taurus has been recently having problems maintaining a smooth idle and seems to be related to the headlights and dome light dimming/brightening in a sort-of random flicker/short fashion. This problem only happens when the car is below 1000rpm.
At first, i thought it might be a vacuum/fuel/sensor problem causing the rough idle, therefore causing the alternator to pop in and out of a charging state. (when the alternator drops below 600 rpm, it may stop charging the system). I tried replacing the wires, plugs, coil pack, alternator, battery, mass air flow sensor, idle air control valve, injectors, checked compression on all cylinders, and everything is running PERFECTLY, other than the dimming lights. I took the vehicle to the ford dealer and they flashed the computer, ran a whole battery of tests on the car and found nothing wrong. I'm not getting any codes, all cylinders are firing properly, injectors are within range, fuel pump is providing the correct pressure, etc.
Everything I've done points to an arbitrary power draw from a circuit in the car causing increased load on the alternator and slowing the engine down, causing the system to compensate and provide increased idle speed. The problem is very much like turning the rear defrost on and off very fast. When the defrost is turned on, it dims the lights and slows the engine down for a brief second until the idle speed compensates for the new load and brings it back to ~700 rpm like it should.
With the defrost OFF, the lights faintly flicker and idle speed fluctuates ~100 rpm constantly trying to compensate. Sometimes, the flicker goes away completely and the engine idles at almost EXACTLY 700 RPM until the flickering returns and the engine responds, so I know the idle/flicker problems go hand-in-hand.
Other than throwing parts at this issue, I have taken out one of the headlights and measured the voltage at the headlight plug and noticed that when the flickering isn't happening, the voltage at the light maintains ~14.2v, but when it's flickering, the voltage fluctuates from 13.2v to 14.3v. When the flickering isn't happening, and i turn the rear defrost on and off, the voltage also jumps between ~13-14v and also causes the idle to readjust.
I have, one-by-one, removed almost every fuse to try and narrow down the circuit causing the problem at no avail. (there are some circuits that i cannot disconnect, such as the fuel pump). I have tested the ground to the body and engine and when the car is off, voltage is perfect. When the car is running and flickering, voltage pops between 13 and 14v.
I am at the end of my rope with this problem and have no other avenues to explore, so here I am, hoping beyond hope that someone on these forums will have a similar experience or solution for my problem.
Edit: Also, I've read that disabling the DRL (daytime running lights) could solve the problem. However, the 2006 seems to have the DRL module integrated with the computer, so it's not possible to just pull a fuse and disable it. I am also inclined to believe that it's not the DRL because the flickering doesn't go away when i turn my lights to the on position.
My Taurus has been recently having problems maintaining a smooth idle and seems to be related to the headlights and dome light dimming/brightening in a sort-of random flicker/short fashion. This problem only happens when the car is below 1000rpm.
At first, i thought it might be a vacuum/fuel/sensor problem causing the rough idle, therefore causing the alternator to pop in and out of a charging state. (when the alternator drops below 600 rpm, it may stop charging the system). I tried replacing the wires, plugs, coil pack, alternator, battery, mass air flow sensor, idle air control valve, injectors, checked compression on all cylinders, and everything is running PERFECTLY, other than the dimming lights. I took the vehicle to the ford dealer and they flashed the computer, ran a whole battery of tests on the car and found nothing wrong. I'm not getting any codes, all cylinders are firing properly, injectors are within range, fuel pump is providing the correct pressure, etc.
Everything I've done points to an arbitrary power draw from a circuit in the car causing increased load on the alternator and slowing the engine down, causing the system to compensate and provide increased idle speed. The problem is very much like turning the rear defrost on and off very fast. When the defrost is turned on, it dims the lights and slows the engine down for a brief second until the idle speed compensates for the new load and brings it back to ~700 rpm like it should.
With the defrost OFF, the lights faintly flicker and idle speed fluctuates ~100 rpm constantly trying to compensate. Sometimes, the flicker goes away completely and the engine idles at almost EXACTLY 700 RPM until the flickering returns and the engine responds, so I know the idle/flicker problems go hand-in-hand.
Other than throwing parts at this issue, I have taken out one of the headlights and measured the voltage at the headlight plug and noticed that when the flickering isn't happening, the voltage at the light maintains ~14.2v, but when it's flickering, the voltage fluctuates from 13.2v to 14.3v. When the flickering isn't happening, and i turn the rear defrost on and off, the voltage also jumps between ~13-14v and also causes the idle to readjust.
I have, one-by-one, removed almost every fuse to try and narrow down the circuit causing the problem at no avail. (there are some circuits that i cannot disconnect, such as the fuel pump). I have tested the ground to the body and engine and when the car is off, voltage is perfect. When the car is running and flickering, voltage pops between 13 and 14v.
I am at the end of my rope with this problem and have no other avenues to explore, so here I am, hoping beyond hope that someone on these forums will have a similar experience or solution for my problem.
Edit: Also, I've read that disabling the DRL (daytime running lights) could solve the problem. However, the 2006 seems to have the DRL module integrated with the computer, so it's not possible to just pull a fuse and disable it. I am also inclined to believe that it's not the DRL because the flickering doesn't go away when i turn my lights to the on position.