Mon. afternoon, I was driving home and I accelerated from 40 MPH to about 55 to pass a Mazda on my way home. I noticed the truck wouldn't kick down into OD. I hit the pedal and let off back and forth between 40 and 65 and still couldn't get it to kick down. I even let it fall all to way down to second gear and then back up to speed and the OD wouldn't kick down. Then I hit a light and completely stopped; I left the light and accelerated up to 50 and the OD kicked down like it was supposed to. I've not had that problem or any shifting problem since.

Today, I got home from work and put the truck in park in the driveway and the RPMs wouldn't fall down to 600 or so like they normally do. They just stayed right around 900 and surged back and forth between 900 and 1000rpms. I stepped on the pedal a bit to make the RPMs jump up to see if it would settle back down but it wouldn't. The idle just hung there.

Could a wonky TPS cause both or either of these problems?

 

Surging I would assume it to be the TPS. I did have an IAC motor that caused my truck to idle at 1300rpm's but it definatly didn't surge. As far as kickdown, I thought the kickdown was cable controlled.

 

It's possible
It might have shorted and be staying at a constant voltage. Eg. 1/2 throttle

 

check youre kick down cable it has a 1/8 of an inch play from center hole both sides and youre fluid make sure youre not sucking in unmeter air it would raise youre idle is youre check engine light on chrysler trans fluid check trans warmed up and in neutral.if youre iac motor was bad it would hard start when cold

 

no hard start issues. TV cable is fine I'll check fluid tomorrow when there's light out, but I don't think that's the idle prob.

did notice one other symptom: seems to take just a little too long for the engine to slow down after you let off the gas and hit the brakes. making me think more and more the tps is bad.

 

sounds like the tps that i replaced in both of my dakotas (5.2L and 5.9L)

 

Found the problem.

Idle air counts were too high.

When I replaced the IAC from the last one that went bad, I didn't attempt to set the Idle Air Counts. The PCM has been trying to adjust for the new IAC by using the old figures. It's not doing a good job and the IAC is compensating too slowly after letting off the gas and braking. The engine "hangs" just a little too long.

Here's the snippet from the FSM:
The IAC is called a stepper motor because it is
moved (rotated) in steps, or increments. Opening the
IAC opens an air passage around the throttle blade
which increases RPM.
The PCM uses the IAC motor to control idle speed
(along with timing) and to reach a desired MAP during
decel (keep engine from stalling.

And another:
When engine rpm is above idle speed, the IAC is
used for the following:
² Off-idle dashpot (throttle blade will close quickly
but idle speed will not stop quickly)
² Deceleration air flow control
² A/C compressor load control (also opens the passage
slightly before the compressor is engaged so
that the engine rpm does not dip down when the
compressor engages)
² Power steering load control
The PCM can control polarity of the circuit to control
direction of the stepper motor.
IAC Stepper Motor Program: The PCM is also
equipped with a memory program that records the
number of steps the IAC stepper motor most recently
advanced to during a certain set of parameters. For
example: The PCM was attempting to maintain a
1000 rpm target during a cold start-up cycle. The last
recorded number of steps for that may have been
125. That value would be recorded in the memory
cell so that the next time the PCM recognizes the
identical conditions, the PCM recalls that 125 steps
were required to maintain the target. This program
allows for greater customer satisfaction due to
greater control of engine idle.

 

Replaced the iac now how do I get the rmp's down?It seems to want to stay around 1800 rmps.Need the reply as soon as possible!!!

 

So, how does one go about resetting the Idle Air Counts when a new IAC has been installed? Disconnect the ground from the battery for a couple of minutes?

 

Yes thats how I got mine to go down.That or pull the negative cable and leave the ignition on for a minute the connect and try again.