Engine Performance problem
1997 Dodge Caravan 6 cyl Front Wheel Drive Automatic 129000 miles
My brother's '97 Caravan has had an intermittent problem for at least a year. While driving or idling it will suddenly stop running. Sometimes it will cough and sputter. Other times he says, while coasting, it will suddenly start back up on it's own. There is no starter noise. It's as if the engine is still turning, but with no spark. The check engine light is frequently on but other times off. Don't know if this is related but all dashboard lights can go off when it dies while driving. Could this be a bad EGR valve? Only code listed is P0106. I'm thinking the computer could cause all of these symptoms. All grounds appear okay but with wiring it's hard to tell. Can a computer be bought and installed from a boneyard with no special programming?
P0106 could be caused by: * Bad MAP sensor
* Water/dirt intrusion affecting MAP sensor connector
* Intermittent open in the reference, ground, or signal wire for the MAP sensor
* Intermittent short in the reference, ground, or signal wire for the MAP sensor
* Ground problem due to corrosion causing intermittent signal problem
* Bad PCM (do not assume the PCM is bad until you've exhausted all other possibilities).
Using a scan tool, watch the MAP sensor value with the key on, engine off. Compare the BARO reading with the MAP reading. They should be roughly equal. The voltage for the MAP sensor should read approx. 4.5 volts. Now start the engine and look for a significant drop in the MAP sensor voltage indicating the MAP sensor is working.
If the MAP reading doesn't change perform the following: 1. With the Key on, engine off, disconnect the vacuum hose from the MAP sensor. Using a vacuum pump, pull 20 in. Of vacuum on the MAP sensor. Does the voltage drop? It should. If it doesn't inspect the MAP sensor vacuum port and vacuum hose to manifold for a restriction of some kind. Repair or replace as necessary.
2. If there are no restrictions, and the value doesn't change with vacuum, then perform the following: with the Key on and engine off and the MAP sensor unplugged, check for 5 Volts at the reference wire to the MAP sensor connector with a Digital Voltmeter. If there is none, check for reference voltage at the PCM connector. If the reference voltage is present at the PCM connector but not the MAP connector, check for open or short in the reference wire between MAP and PCM and retest.
3. If reference voltage is present, then check for existing ground at the MAP sensor connector. If it isn't present then repair open/short in the ground circuit.
4. If ground is present, then replace MAP sensor.
December, 2, 2008 AT 8:58 AM
Thank you for your help. We'll check MAP sensor and wiring this weekend. The dealer said they checked the wiring and sensors but you never know.