2002 Dodge Caravan - 3.3L Crank Sensor Problem

[gale]

Help

We have this 2002 Dodge Caravan with a 3.3L engine, check engine light came on was code P1391 - cam/crank signal -- replaced both the cam and crank sensor, was worse, rescanned then was just code for crank tried 2 other crank sensor was even worse, one would not start, other would start put in gear and stall then got in a dealer crank sensor did same thing as original symptom (check engine light, jerking when accelerate) and checked all the wiring etc.., put the old crank sensor back in and ran good, road tested many times was good, customer picked up and on way home now driving at a constant speed when put a load on engine (going up hill) would start to shutter. Not sure where to go now - still believe it needs a crank sensor but not sure what to use.

Gale

[Tim Martin]

Not sure if this will help or not but I connect my lab scope and watch both sensor waveforms at the same time. This code (P1391) means intermittant loss of either camshaft or crankshaft signal. I have run into this and more often than not it was the camshaft sensor was the problem. If I replace the crankshaft sensor, I replace the wiring harness as well. Also, I use only OEM sensors. One issue we have seen is a broken flywheel on these engines that can also set this code because the cam and crank sensors looses its correlation like the PCM wants to see.

[steven kiser]

I'm willing to bet that the original crank sensor had a groove cut in it. I'd be surprised if the transmission is the original so the first thing i would look at is the fly wheel. I put a socket and breaker bar on the crank pulley anchor bolt and yank it back and forth, if there is a clattering noise you have a broken flex plate. I've also seen where the flex plate was damaged (the toner ring had a deviation in it from being bumped) and it would tear the sensor apart. I've also had situations where i took a match book cover and glued it to the tip of the sensor and pushed it tight against the fly wheel and secured it. Years ago when the sensors were purchased from the dealer there was a paper slug on them.

Take a bad sensor and slip it in the hole. apply slight pressure to it and have someone crank the engine over. If there is a deviation in the plate you'll feel it. Use the sensor, nothing else, especially your finger. Yes i've seen the result of that happening.

[ricmorin]

Check the flexplate....cracks are common on these.

[gale]

Thank you, I will pass this onto my Tech. Actually it is the Original transmission this van only has 109515 km on it. That makes sense cause it seems strange that 4 sensor would be faulty including the OEM Sensor. I'll let you know how everything worked out. ]

Thanks Guys

[jbadenoch]

sounds like it may have a bad cam or crank sensor, however, the description of how its running sounds like a mis-fire. I would see if I could re-create the "shuttering" in the shop, then see if you can identify which cylinder is mis-firing, then find out why. maybe it has 2 issues and the issue with cam or crank sensor is not causing the "shuttering".

[mopwrforme]

well acouple of differant things I would first ck. the flywheel. if that is in good working order the other thing that comes to mind is tq shudder. 604 trans had issues with there tq going in and out of lock up causing a shudder. apx. 45mph with the scan tool watch for tcc engagment in the datastream if thats causing the shudder you should see it
one last thing is good old spark plug wires or coil. with this modle under a load they will breakdown and also cause a shudder or misfire under load but be fine at idle.