Shifting problems

[mxo41]

I have a 96 cherokee with 4.0L, AW4 transmission and 102,000 miles. After driving on the highway for an hour going 70 mph the engine seems to jump for 2200 rpm to 2600 or even 3000 rpm. There is a loss of power at these high rpm. I have checked transmission fluid and it looks fine. Gas mileage is also low around 13-15 mpg. Another problem maybe related or not is the four wheel drive light does not go on. Checked fuses and all look fine. Any ideas on where to look.

[Bounty__Hunter]

Have you had the transmission serviced? Fluid and filter? It may help if it needs it.

Otherwise I'd suggest taking it somewhere they can hook it up to diagnostics and find out exactly what isn't working in the tranny. Shouldn't be hard since the AW4 has it's own computer.

[XJNick]

Hi,

Sounds like maybe the Torque converter is slipping/releasing when it shouldn't be? I agree with Bounty, see if you can find a way to check the transmisison's computer system. You should be able to do this through the Powertrain Control Module (PCM aka main computer) using an OBD-II style scanner.

-Nick

[mxo41]

I hooked up the jeep to an OBD-II scanner but it passed. I am not sure but i thought OBD-II scanners only worked when the check engine light comes on. Since mine was not on I think it passed. I was wondering if maybe the Throttle Position Sensor could cause this problem of shifting. I heard that even if it is bad it can give a voltage in the expected range so the check engine light will not come on.

	Throttle position sensor A throttle position sensor (TPS) is a sensor used to monitor the position of the throttle in an internal combustion engine. The sensor is usually located on the butterfly spindle so that it can directly monitor the position of the butterfly throttle valve. The sensor is usually a potentiometer and therefore provides a variable resistance dependent upon the position of the butterfly valve (and hence throttle position). The sensor signal is used by the Engine Control Unit (ECU) as an input to its control system. The ignition timing and fuel injection timing (and potentially other parameters) are altered depending upon the position of the throttle, and also depending on the rate of change of that position. For example, in fuel injected engines, in order to avoid stalling, extra fuel may be injected if the throttle is opened rapidly (mimicking the accelerator pump of carburetor systems).

[XJNick]

Hi,

You need to use the scanner to read any transmission codes that may exsisit. OBD-II does throw many codes that do NOT light the check engine lamp.

Also, a throttle position sensr could cause erratic shifting, but would most likely cause the engine to run poorly or sparaticly as well

-Nick

[mxo41]

Well i went to the dealer and had them test everything. They said that all three solenoids (my guess would be just the 3rd-overdrive one but i think they wanted extra money) in the transmission for shifting were bad. Does someone know how to change these and where i can buy them? Any help would be great. Dealers overpriced estimated was $1322.

[dingus]

download the 112 page (4 mb) manual i have for the AW4 tranny here...

http://www.natecovington.com/downloads/AW4.pdf