Idling High while driving

My check engine light came on today and while driving, the idle (RPM's) were very high. At about 80KMs, it was about 3500 and when I accelerated, the engine would race along with the RPMs. While stopped, idling seems fine. I couldn't get over 80KMs/Hr without the idle going too high.

Any ideas as to what it could be? Haven't had time to check codes as it is long weekend and garages are now closed till tuesday.

Thanks

Model year? 4 speed transmission?

It is a 2005 Grand Caravan 3.3L and I think it is 3 speed ( Drive/3 and L)I pulled a code off the dash as I don't have a reader and it came back with code
P0700. Any idea what to look for. I'm not a mechanic so I don't have all of the tools but I can have a look.

P.S: After reading the code, I disconnected the battery to reset the code and took it for drive. I went about 10KMs and the light came back on. Read the code same P0700.

Thanks

still have the same code P0700. I removed the battery, drove it for about 5 mins, came back. The transmission doesn't seem to have any issues as I drove it this morning, and the RPMs are back to normal. How can I tell if it is the actual transmission or a sensor without knowing the codes? I dont have much $$$ so Im trying to look for anything that may be obvious.Any help would be great

po 700 is a dtc set in the engine computer telling you that there is a dtc in the trans module. You need a scanner to pull that code

I got the input speed sensor replaced, light was off for a couple of days, then back on, same P0700 code. How can I tell if the problem is due to a sensor or the transmission.What symptons would I experience if it was a mechanical fault like the actual transmission and not a sensor?

as mentioned in my previous post po700 is just telling you that there is a fault code in the tcm (trans control module) which is a diiferent ecm than the engine ecm..you need a scanner that can access that code in the TCM.......

as mentioned in my previous post po700 is just telling you that there is a fault code in the tcm (trans control module) which is a diiferent ecm than the engine ecm..you need a scanner that can access that code in the TCM.......

I got the tranny shop to read the codes. Got P0700 and P1776. Something about a selonid.Does this sound correct!!

These are the possible causes for that code. You need a qualified trans shop to diagnose the problem. Most likely it does not need an overhaul as long as the pan is free of debris...


POSSIBLE CAUSES
RELATED DTC P0841 PRESENT
CHECK THE DTC EVENT DATA FOR TRS CODE TR2
L/R PRESSURE SWITCH SENSE CIRCUIT OPEN
L/R PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND
L/R PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
INTERNAL TRANSMISSION - SSV STICKING
VALVE BODY
POWERTRAIN CONTROL MODULE
INTERMITTENT WIRING AND CONNECTORS

Well changed the selinoid the code is now gone. However tonight as I was just driving along at a normal rate (60KM/Hr) the RPMS shot up , van kicked in then settled down again. It done this several times. What could be the cause?No Check engine light, no codes.

with the battery disconnected, can you pull the wire plugs and check them? oily/greasy/bad seals. the transmission plugs mounted on the transmission, like the transmission control module, speed sensors, etc., get hot and end up cracking, maybe dry rotting the seals, allowing water/oil/etc to enter. the valve covers and intake love to somewhat leak oil and seems to collect on the plugs down on transmission. i have had these problems on 2001/2005. oh and make sure the ground is tight, it is right by the TCM, just follow the black/negative down, is mounted to transmission and engine block. we had a defective ground at that location, the wire strains were coming apart from the eyelet that bolted there. both these problems affected our transmission without a code. i used brake cleaner to clean the plugs and connectors, it evaporates fast, i used an air gun to help dry out too. some probably dont agree with using brake cleaner but it worked for me. before you went to shop, did you get the code from cycling your key?

as far as your idle goes, i had a couple vacuum hoses by the belt side that caused the rpms to go up and down, maybe check them too. there are a couple of vacuum lines that are really hard to find, think you may need to remove the air cleaner hose to get better access. some hidden ones are by motor mount and underside of air intake.

another thing maybe to check it your throttle body/air intake, the flap can stick or not close all the way...wouldnt hurt to really clean it, the IAC plunger too, it is connected to your intake, i took mine off to clean it, is way easier and can do a better job. they sell a cleaner for air intake but i used alcohol and a toothbrush. careful not to break intake seal.

im not a pro transmission person but i have had alot of different transmission problems and through out it all, i have not noticed the transmission causing the rpm to react like yours. i have had the problems listed above cause rpm differences, high to low, then good, then back...

i remember a rpm issue and the brake booster check valve was bad, something like that...

also read how to reset trouble code light...

Sit in the driver's seat, turn the ignition key to the "Accessory" position for about ten seconds and then turn it off. Do this three times.
Crank the engine on the fourth turn of the ignition key. Let the engine run until the engine warning/malfunction light goes out. If the light does not go out after one to two minutes, shut the engine off and open the hood.

a scan tool can erase codes but if dont have one, disconnect the negative, and think you need to wait at least a half hour for the vehicle's protection system to lose its memory and reset the light. and sometimes it may only take a scan tool to erase a touble code...

just giving you some ideals ive had problms with in the past that wont throw codes...hope this helps...

I put the van in 3rd gear, the rpms was steady. As soon as I put it into drive it acts up. I was told if this was the case could be a torque converter issue.If it were a vac leak, should I not see it regardless of what gear it is in? I've had the TCm replaced and one of the speed sensors. Also, someone told me it might be related to my wheel bearing if my van is out of alignment??

You need to google TSB 21-004-06. Trans will go into lock-up even when it is in 3rd; so the torque converter is not the issue. Not a vacuum leak or a wheel brg.

good info on the TSB, if you verified that the rpm issue happens when shifting from 3rd to 4th, and you threw the TSB code before, you should have that checked into and corrected first. the high idle from a transmission problem is new to me. the idle issues i discussed was more concerning your engine managment and not related to the transmission.