Question96 Dodge Caravan 3.3L
Weeks ago van started intermittent cycle as follows:
- attempt start... won't start
- turn off ignition
- attempt start... starts fine
- Service Engine Soon light comes on (code 54)
- random period of time passes (could be hours, could be days)
- engine dies shortly after starting
- attempt restart... starts fine
- Service Engine Soon light turns off (computer reset?)!
- random period of time passes (could be hours, could be days)
- cycle repeats itself!
Replaced camshaft position sensor (in response to code 54)... 1 week later, above cycle occurs again. Replaced timing chain and timing gears (it was worn and "clicking" anyway)... two weeks later, above cycle occurs again. Also, poor fuel economy... replaced upstream O2 sensor (in response to occasional code 21)... still having poor fuel economy.
HELP! Thanks!
AnswerHi Larry,
At first I thought what you were describing was consistent with a failing hall effect sensor, but because this appears to be a problem that occurs when you start the engine from cold I feel less certain about that theory.The hall effect crystal usually fails after it heats up, then recovers upon cool down. Your description sound more like an intermittant electrical connection situation. If the code returns always to be a 54 then I guess you have to focus on the cam sensor but I wouldn't let the crank sensor off the hook.
In any case you will have to catch this "in the act" and be ready to make voltage measurements when it won't start. I would use some fine straight pins to measure the voltage on the orange wire at the crank sensor with the ignition "on". It should be 8 volts. Then probe between the other two wires, light blue/dark blue (+) and black/light blue (-) and again, with the ignition "on", rotate the crank pulley be hand using a socket and breaker bar and notice whether the voltage varies between 5.0 and O.3V. If not, then the sensor is bad or the wiring from it to the controller has a break in it. Similarly do the same two measurements at the cam sensor plug where the wire colors are similar except the tan/yellow takes the place of the light blue/dark blue.
But it won't be revelatory if after you do the test the engine starts; so you have to get it done quickly. If it seems to be in intermittant related to a wire break I can give you the pin numbers at the engine controller for you to be able to check the the continuity of those 6 wires.
I would keep watch for other fault codes too. And you can erase the codes by disconnecting the battery for a few minutes. Another possibility is an inaccurate MAP sensor which would give you poor economy. If it isn't totally failed, just inaccurate, it won't set a fault code and still behave this way.
So those are my suggestions. You could also test the broken wire theory by shaking the harness from the sensors to the controller while the engine is running.
I'd be glad to know what you learn.
Roland
I would also do the same test on the
