Methix

Ok, this is a really novice question. I drained and replaced the transmission fluid in my 2001 Cherokee Limited (AW4 I believe) since I have no idea when the previous owner last did anything with it.

I put in Castrol Transmax DEX/MERC (http://tinyurl.com/a8rdhrn). I was pretty sure this was the right stuff, but now I'm getting a little bit of a burning smell and it's shifting just a little bit rough. That is the correct fluid, right?

I checked the fluid level and it's spot on, so I don't think that's the issue. Also, it's been a few weeks so it's not just burning off fluid that splashed or anything.

Any other thoughts?

Thanks!

tjwalker

The fluid you put in your AW4 is fine.

Two other things can come into play for improper shift points. Neither are particularly difficult to verify.

1. Throttle position sensor. Extremely important for AW4 shift points. More on that sensor and how to test it below.

2. Adjust TV cable. Here is a link.

https://www.cherokeeforum.com/f2/free-quick-fix-41821/

----------------------------------------------------------
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.

Xjtim

Wrong fluid, take it out as soon as possible. You need ATF+4 for the AW4 trans.

tjwalker

Disagree.

Asin Warner, the mfg of the AW4 recommends Dex/MERC. It has since it designed this transmission.

Chrysler, in their infinite wisdom a while back, came out with a bulletin stating that ATF+4 was okay for the AW4. Unfortunately, some AW4s work okay with it and some have slippage. NO AW4s have slippage with Dex/Merc and it continues to be the fluid recommended by the MFG of the transmission.

He is fine with it and there is no need to change it.

Methix

Wow, thanks for all the good data. I'll check those things tomorrow. FWIW, this definitely happened immediately after I changed the fluid (the burning and shifting) so is it all that likely that either of those things would have coincided with a fluid change?

One thing I forgot to mention. When I first replaced the fluid, I think I overfilled it a bit. I've since drained it back down and am pretty confident it's at the proper level now (that was a few weeks ago).

mdnov

Actually.......It depends on who you talk to. All AW4's came off the line with Dexron II/III just look at the original drain plug. The AW4 is actually a TOYOTA transmission, not a Chrysler transmission. The original owners manual actually says to use the Dexron as well. Only the FSM says to use ATF+4.

mdnov

TJ-
You said it much better than I did.

DieselDaze

you say its up to level?? you are checking it with the engine and tranny hot and while idling right??

you may have got some tranny fluid on the exhaust while filling it up...

Methix

To check the fluid level, I first drove about 10 miles at 65mph. Then had it idling, in neutral (with the parking brake on), and checked the level.

I had thought it might have just been fluid on the exhaust, but it's been several weeks so anything should have burned off by now.

Radi

They did. After the last AW4 was out of warranty.

Chrysler's testing was done with brand new AW4's, and in a brand new trans it's probably fine. In a trans that's already run 100K miles with Dexron, switching to +4 is sometimes troublesome.