mrhorsepower77

Any and all ideas would be appreciated. After the Butler Jeep Jam I didn't get all the mud pressure washed out of my rad and the Jeep ran hot all the way home. Didn't help that the mud burnt up my electric fan too. Only had a twenty minute drive and made it home. New fan, cleaned out the radiator good and now tranny boiled over on my way to the Nemicolin Jeep Jamboree. Pressure washed out the rad again and made it home. This week I changed the fluid twice and installed a fairly large tranny cooler to the front of my rad on the drivers side. Last night I went for a little ride and it started shifting funny so I headed home, smells like the tranny is hot again. What am I missing? I didn't drop the pan and change the filter but before the boil over I had just did it, figured I would change the fluid twice and that would be good. Is it really possible to put the cooler on wrong, didn't think that was rocket science. I just tapped into the return line back to the tranny after it ran through the radiator. Felt the cooler and it didn't even feel warm, but the rubber hose going to and leaving was. PLEASE, IDEAS!!!

ZINGGG

Did you add more tranny fluid to account for the capacity of the cooler?

mrhorsepower77

I did.

ZINGGG

Was the cooler brand new? Or did you pull it from a JY? Just to make sure it has good flow in it

Bbasso

If you were flexing the suspension a bunch you might have pinched one of the hard lines underneath. Have look.

tjwalker

Throttle position sensor is ALWAYS in play for shifting issues with the AW4.

And the TPS hates moisture. So if it got wet, it is very high on the suspect list.

Here's more.
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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 accordingly 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 denied acceptable range causing the ECU to incorrectly fuel the engine. This is noticeable 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.

maybe2fast

my trans overheated and purged out TC seal and a day later it was time for a radiator...clogged. never happened again after the two row rad. runs at 200*

mrhorsepower77

Trans cooler was a brand new Advanced Auto unit. Just replaced my TPS sensor to try to fix a stumble upon acceloration problem, it didn't fix that problem. Engine light calls for o2 sensor. Replaced one of those too, just not the one towards the rear. I am hoping that replacing that one fixes that issue. Tranny lines are good. I have spent everyday off for six months trying to get my Cherokee reliable and able to pass PA inspection, I'm getting annoyed. Just about everything is new the only thing that isn't (the starter) is going bad and I will be replacing. Think it is a clogged radiator? If so, any ideas on a model/make to buy?

mrhorsepower77

Did you just put in a factory Mopar rad or a certain brand?

maybe2fast

https://www.cherokeeforum.com/f67/up...diator-142290/

sthon

This happened to me. One of the lines on my trans cooler was pinched damn near shut, every time I would be going up a grade at highway speeds I would dump ATF on the exhaust.

maybe2fast

when my rad was done, it was running at like 225 and on the E-way the trans would dump on the exhaust