It rained last night,it always ran fine before,i also heard the pcm could be getting moisture do to a bad design
A flashing engine light usually indicates a misfire or several misfires. If the ignition components (coils, wires, distributors...) some how become exposed to moisture it is possible to get a rough running engine due to misfire(s) cause by arcking.
thank you ,i guess i could start with plugs and wires,may be coil pack,some say this did nothingand others say dry out the power control module?
A spray bottle with soapy water can help isolate and reproduce the problem. Spray the ignition components and check for arching. Replace any faulty components. Also a scanner can help identify which cylinders are misfiring making it easier to pinpoint any issues.
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SOURCE: engine runs rough at certain speeds 3.0 v6 flex-fuel 1999 ranger
Check and see if the EGR valve is leaking, to check this spray water on it at idle, if the water steams off the valve is leaking and is the source of your problem, also are you sure you hooked the new DPFE sensor up right? re-check it..
SOURCE: 2004 Ford Freestar missing Possible fuel pump?
if you have a bad spark plug wire, it will draw condensation and make engine run rough.... you can check this by getting a spray bottle and filling it with water, spray a mist over top of the wires while the car is running, and if one is bad it will show.... (looks like little lightning coming off of wire) .... hope this helps
SOURCE: 1999 ford expedition - transmission slip?
the flashing O/D light usually means you have a bad speed sensor that sends speed info to the engine & trans computer.
Vehicle Speed Sensor
The vehicle speed sensor (VSS) (Figure 42) is a variable reluctance or Hall-effect sensor that generates a waveform with a frequency that is proportional to the speed of the vehicle. If the vehicle is moving at a relatively low velocity, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the VSS (and other inputs) to control such parameters as fuel injection, ignition control, transmission/transaxle shift scheduling and torque converter clutch scheduling.
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Vehicle Speed Sensor
The vehicle speed sensor (VSS) (Figure 42) is a variable reluctance or Hall-effect sensor that generates a waveform with a frequency that is proportional to the speed of the vehicle. If the vehicle is moving at a relatively low velocity, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the VSS (and other inputs) to control such parameters as fuel injection, ignition control, transmission/transaxle shift scheduling and torque converter clutch scheduling.
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Some trans use an OSS, Output Shaft Sensor instead of a VSS. Depends on which trans you have, 4R100 or 4R70W
Transmission Control Switch (TCS) and Transmission Control Indicator Lamp (TCIL)
The transmission control switch (TCS) is a momentary contact switch. When the switch is pressed, a signal is sent to the powertrain control module (PCM) to allow automatic shifts from first through fourth gears or first through third gears only. The PCM energizes the transmission control indicator lamp (TCIL) when the switch is off.
The TCIL indicates overdrive cancel mode activated (lamp on) and electronic pressure control (EPC) circuit shorted (lamp flashing) or monitored sensor failure.
Output Shaft Speed (OSS) Sensor
The output shaft speed (OSS) sensor is a magnetic pickup, located at the output shaft ring gear, that sends a signal to the powertrain control module (PCM) to indicate transmission output shaft speed. The OSS is used for torque converter clutch control, shift scheduling and to determine electronic pressure control.
SOURCE: What is the PCM in
The pcm is located Under the windshield wiper coil on the passenger side of the engine compartment, where water can collect.And yes if its get wet it can get short.The radio,the ac the lights and other electrical functions works intermittently .The cost of pcm is near to $1000.You can get it from autozone service center or from local auto part stores.
---------This will help.Thanks.Helpmech.
SOURCE: I have a 2004 freestar
I just had the same thing. Engine light came on. Rough idle. Codes P0171, P0174, P2195, P2197. Within a week the idle got so bad it would die at stop lights. Seemed like a vacuum leak affecting the idle. Found it today. The elbow where the PCV tube enters the vacuum port on the upper intake was degraded, collapsed and had a whole in it. Wondered why it degraded. I disconnected the tube from the PCV valve and found it quite oily. I think the oil sat in the elbow at the intake because it is flat on top of the engine and could pool there, causing the rubber to degrad. Found a preformed piece of coolant hose at O'Reilly that was the right diameter and cut it to length. Put it on, runs like a charm. I ordered a new PCV valve because I think too much oil was coming through it and caused the hose failure.
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