94 T&C van hesitations at 60mph

My 1994 Chrysler T&C van, 3.8L AWD auto, has developed a nagging problem.
Intermittantly, under low load at around 60mph when well heated up, it
will give a series of very fast lurches/hitches. This is about as fast as
you say "jerk, jerk, jerk" in normal speech. The digital tach jumps from
around 2000rpm to over 4000 each time but it is just a flash for each
jerk.

I can now make this happen pretty regularly at the same spot on the
highway. After 10-15 miles of driving to warm up, I go up a long,
cross-over off-ramp at about 45mph. The other side slopes downhill. At
the bottom, I am going 50 to 55 mph and the grade changes to uphill. I
add a little throttle just to maintain speed and, "jerk, jerk, jerk".
Having sped up, it goes away. I find it weird. I am worried it will
strand me in a difficult situation.

I did a tune up with plugs, wires and oxygen sensor, no difference. A
trans shop and a Chrysler dealer both looked at the tranny as I thought it
might be dropping in and out of lockup but they found nothing odd. There
are no recorded error codes according to them.

Any help/ideas would be greatly appreciated.

Donn F.

 

If the tach is jumping around it's most likely the crank sensor.
Larry

 

That is what I would say also. Bad crank sensors can be affected by temp,
they will
work fine when cold but stop working when they are hot. And in that year a
bad crank
sensor will not set an error code in the computer.

Ted

 

Hi jdoe & Ted -
I changed the crank sensor and have not had the problem recur. I did the
overpass a couple of times that used to set it off and NOTHING! It is
looking good. Intermittants are such a pain. Thank you so much!

Donn