1997 Dodge Ramcharger Starts & shuts down-then cranks &

JANA F

MEMBER
1997 DODGE RAMCHARGER
V8
4WD
AUTOMATIC
145,000 MILES

On my way to work my truck began to run rough and my check engine light came on, Ran the codes, had code for misfire on #8, pulled the plug, oil & fuel fouled.
Tested the compression, 90lbs on the #8 cylinder. Removed the valve cover. Replaced the valve seal and the retainer on the exhaust side at that same time I did a complete tune up. Ie: plugs, wires (rerouted) cap, rotor & Coil. New code insufficient dwell. Tested & replaced the PCM. My truck ran better than it ever has. For two days. I always warm my truck up before I have to leave, while in warm up it shut down and would not restart. Next day started right up, ran for about 5min and shut off. Same on the next day. I have tested the ASD, Cam sensor, Crank sensor, fuel relay & fuses, all are within specs. I'm not a mechanic, but I do OK for a girl, can you point me in a new direction?

1 Reply

CARADIODOC

MECHANIC
33,916 POSTS

How are you testing these things? The cam and crank sensors are likely suspects but there should be a diagnostic fault code memorized in the Engine Computer. Also, all of these things are working properly when the engine runs. When the engine warms up is when something fails. Any testing will likely not show up a problem since the parts will be cooled down.

Do you have a cheap digital voltmeter or a test light? The place to start is by determining if the Automatic Shutdown (ASD) relay is turning off causing the stall. Measure the voltage on the ignition coil, injector feed wire, or my favorite, on one of the small wires on the back of the alternator. When you turn the ignition switch on, voltage will be there for only one second, then it will go away. The fuel pump will also run for that one second. You might hear it run too. Hearing the pump or seeing the voltage for that one second proves the Engine Computer can turn on the ASD relay. After that one-second burst, the relay should turn on again and you'll see the voltage come back when the engine is rotating (cranking or running).

Once the engine stalls, if the voltage doesn't come back during cranking, the ASD relay isn't turning on. The Engine Computer turns the relay on when it sees pulses from the crankshaft position sensor and camshaft position sensor. Either of these sensors can be heat sensitive and fail when they get warm.

Caradiodoc