snoopdann

I have a 96 Cherokee with 145k miles on it, transmission was acting fine then I got close to work at a light and when I stepped on the gas, engine reved up fine but transmission didn't do anything for a little while then "banged" into gear - as if was trying to build up pressure to engage. Checked levels, they were fine. When it does shift and go thru the gears, it goes thru them fine just has a hard time keeping up with the engine, and going over hills here in Kentucky was very hard to do.

This is my daily driver, so i'm in a hurry to fix it. I found a used transmission locally for $170 that I can get installed quickly - but my overall question is, what is exactly screwed up in my A4 that would give me those issues?

Thanks!

snoopdann

no one?

jomps

fluid for sure. did you check it normal oper. temp. in drive. condition of fluid?..etc

jomps

any leaks, I know you said you checked it but that exact situation happened when the wj leaked tranny fluid and got low....as far as anythin else wrong I dont know

snoopdann

Fluid is almost black, and smells burnt... and its been having a weird shift issue for about a year (but ive not been driving it, ive been overseas) so it basically sat all this time. Fluid level is normal.

tjwalker

Three things come to mind.

1. Just saw an update and said that fluid is black? You need FRESH fluid in there stat!!! That is very likely the problem. I'd recommend dropping the fluid in the pan and refilling with Dex/Merc III fluid. Drive for a couple hundred miles, repeat the above until the fluid stays red in color. Then drop the transmission pan and clean or replace the filter (basically a screen) THEN see where you are at. Fluid wears out. And yours is shot.

2. Your throttle position sensor is directly involved with how your transmission shifts.

3. Adjusting your TV cable
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The throttle position sensor is connected to the throttle shaft on the throttle body. It sends throttle valve angle information to the PCM. The PCM uses this information to determine how much fuel the engine needs. The TPS is really just a simple potentiometer with one end connected to 5 volts from the PCM and the other to ground. A third wire is connected to the PCM. As you move the accelerator pedal with your foot, the output of the TPS changes. At a closed throttle position, the output of the TPS is low, about a half a volt. As the throttle valve opens, the output increases so that, at wide open throttle, the output voltage should be above 3.9 volts. Testing can be performed with an electrical meter. Analog meter is best. You are looking for a smooth sweep of voltage throughout the entire throttle band. While slowly opening and closing the throttle, take note to the movement of the voltmeter needle. There should be a direct relationship between the needle motion to the motion of the throttle. If at anytime the needle moves abruptly or inconsistently with the movement of the throttle, the TPS is bad

You should have 5 volts going into the TPS. At idle, TPS output voltage must be greater than 200 millivolts. At wide open throttle (WOT), TPS output voltage must be less than 4.8 volts.. The best is to use an analog meter (not digital) to see if the transition from idle to WOT is smooth with no dead spots. With your meter set for volts, put the black probe on a good ground like your negative battery terminal. With the key on, engine not running, test with the red probe of your meter (install a paper clip into the back of the plug of the TPS) to see which wire has the 5 volts. One of the other wires should show .26V (or so). The other wire will be the ground and should show no voltage. Move the throttle and look for smooth meter response up to the 4.49 at WOT.

Perform the test procedure again and wiggle and/or tap on the TPS while you watch the meter. If you notice any flat spots or abrupt changes in the meter readings, replace the TPS.

The TPS is sensitive to heat, moisture and vibration leading to the failure of some units. The sensor is a sealed unit and cannot be repaired only replaced. A TPS may fail gradually leading to a number of symptoms which can include one or more of the following: -

NOTE: The throttle position sensor is also DIRECTLY involved with transmission shifting characteristics! It should be verified early in the troubleshooting process, when a transmission issue is suspected!

• Poor idle control: The TPS is used by the ECU to determine if the throttle is closed and the car should be using the Idle Air Control Valve exclusively for idle control. A fault TPS sensor can confuse the ECU causing the idle to be erratic or "hunting".
• High Idle Speed: The TPS may report faulty values causing the engine idle speed to be increased above normal. This is normally found in conjunction with a slow engine return to idle speed symptom.
• Slow engine return to idle: A failing TPS can report the minimum throttle position values incorrectly which can stop the engine entering idle mode when the throttle is closed. Normally when the throttle is closed the engine fuel injectors will be deactivated until a defined engine RPM speed is reached and the engine brought smoothly to idle speed. When failing a TPS will not report the throttle closed and fueling will continue causing the engine to return to idle very slowly.
• Engine Hesitation on Throttle Application: The TPS is also used by the ECU to determine if the driver has applied the throttle quicker than the Manifold Air Pressure sensor can read. The fueling is adjusted acordingly to cope with the sudden increase in air volume, however a faulty sensor can cause the ECU to ignore this data and the engine will "hesitate" when applying the throttle. In extreme cases with the engine at idle, a sudden application of full throttle can stall the engine.
• Engine Misfire: A fault TPS can report values outside the deined acceptable range causing the ECU to incorrectly fuel the engine. This is noticable as a slight misfire and can trigger the misfire detection software and/or Malfunction Indicator Lamp (MIL) light on the dashboard. Extreme cases can cause excessing misfires resulting in one or more cylinders being shut down to prevent engine and catalytic converter damage.
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https://www.cherokeeforum.com/f2/aw4...-isssue-30200/

snoopdann

thanks for posting that. But like I said, it smells burnt. Should I just change the transmission fluid and hope for the best? I mean, $170 for a used tranny isn't too bad insurance right?

tjwalker

I would absolutely change the fluid. It may very well restore better function. I've seen AW4 transmissions at the brink of death that have had a nice long service life with fresh fluid.

If you see NO change after changing the fluid in the pan, then think about that used transmission.

It takes you about an hour of your time and 3-4 quarts of Dex/Merc III fluid (do NOT use ATF+4, no matter what the parts store may tell you).

jomps

yes change it, shouldnt be burnt looking

snoopdann

Allright, fresh fluid it is.


Another issue is that I do have a lot of weight extra in the vehicle (it's 1500 lbs over cub weight) and i'm sort of surprised it even lasted this long. If you're wondering about what the weight is, its for the stereo. 600 lbs in batteries alone.