AW4 slow upshifts

My 1999 XJ revs very high before upshifts. It has a new reman computer and transmission controller. I run 4.56 gearing with 6.5" lift and 35" tires. The trans shifts fine from 1-2(2000-3000rpm). 2-3 revs to 2500 rpms on anything less than 1/4 throttle and at least 3500 to 4000 on half throttle. It would probably blow up if I had the peddle to the floor. 3-4 and lockup seems fine. It also downshifts fine. I have adjusted the TC loose and tight. I run it loose so it will shift sooner. Any suggestions? My TJ with the 32rh 3 speed always shifts before 3000 with the same gear and tire set-up.

Test the "throttle position sensor". It is directly involved with shifting characteristics of the AW4.

It is responsible for many shifting issues.
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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.

I replaced it, never made any difference. Also has new transmission fluid.

Adjust TV cable?

old_man said:

Adjust TV cable?

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Yes, both loose and tight. I run it a little loose right now.

stephenfarris said:

Yes, both loose and tight. I run it a little loose right now.

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What? There is only one correct position for it. Press the button, pull the cable toward the passenger side and then floor the pedal. It will adjust where it needs to be. Its not like the Chrysler TV cables. Did you also check the TPS, just replacing it might not work.

Talyn said:

What? There is only one correct position for it. Press the button, pull the cable toward the passenger side and then floor the pedal. It will adjust where it needs to be. Its not like the Chrysler TV cables. Did you also check the TPS, just replacing it might not work.

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The cable is very tight the way you factory adjust it. The shifts are crisp and firm. If I pull the cable out 1 or 2 more clicks it actually moves the shifts points lower and the transmission is not as firm. I like the way it shifts better this way. My tps has 5.2 volts going in. The output starts at about .64 volts on the idle side and gradually moves to 3.65-3.68 volts at WOT. I have tapped the tps and wiggled it will doing the test and it always starts and ends at the same voltage. I think that it is in the valve bodies myself. One other thing that I forgot is that the trans is slow to going into reverse. It seems to take about 3 seconds to engage whether it is hot or cold. All of the forward gears engage in half the time.

Of all the XJ's I have driven, I cannot remember any of them that shift firm. The AW4 in the XJs are not performance transmission. You need to keep that in mind. The reason for my saying that is the fact that yours shift firm and it is something you want and like. In addition you have a set of re-manufactured and possibly modified or malfunctioning PCM and TCM. Try swapping in some OEM (non-modified) units. They may just solve your shift problems.

techno1154 said:

Of all the XJ's I have driven, I cannot remember any of them that shift firm. The AW4 in the XJs are not performance transmission. You need to keep that in mind. The reason for my saying that is the fact that yours shift firm and it is something you want and like. In addition you have a set of re-manufactured and possibly modified or malfunctioning PCM and TCM. Try swapping in some OEM (non-modified) units. They may just solve your shift problems.

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The TCM is oem. I actually ordered a used one off e-bay before I did anything to see if that was the problem. Both TCMs work the same. The
PCM was the next item to replace before I pulled it and saw that it had already been replaced by the previous owner with a new reman unit. It could be the PCM but it don't think that it would cause the high shift points. I also don't know if the transmission has been opened before. The previous owner had already put the SYE in the transfer case but I have no idea about the transmission. When I got it, the trans pan leaked and I replaced the gasket. The old gasket was a cork/paper style gasket which leads me to believe the trans had not been out.

Did you test with a digital volt meter or an analog? If there is some odd jump the digital might not pick it up. But I would also expect some other issues along with that. The OEM gasket on the AW4 is just RTV. I don't use a gasket either. Just some "Right Stuff" RTV. Never a leak. There is a modification you can do to a few of the springs in the valve body that would make it shift firmer by increasing pressure, but I don't know about holding the shifts longer. Did the XJ have any other performance modifications done to it when you purchased it? Also, inspect the TV cable for any obvious modifications done to it. I know some people had the bright idea to add zip ties to it to get it to shift later. I think a few of them ended in transmission death.

But, that 3 second engage into reverse isn't normal.

Talyn said:

Did you test with a digital volt meter or an analog? If there is some odd jump the digital might not pick it up. But I would also expect some other issues along with that. The OEM gasket on the AW4 is just RTV. I don't use a gasket either. Just some "Right Stuff" RTV. Never a leak. There is a modification you can do to a few of the springs in the valve body that would make it shift firmer by increasing pressure, but I don't know about holding the shifts longer. Did the XJ have any other performance modifications done to it when you purchased it? Also, inspect the TV cable for any obvious modifications done to it. I know some people had the bright idea to add zip ties to it to get it to shift later. I think a few of them ended in transmission death.

But, that 3 second engage into reverse isn't normal.

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I tested with a digital but replacing the tps with a autozone brand did not make any difference so I just left it on there. I have the original as a back up in my parts bin. I have replaced just about every sensor. The engine overheated and messed up the head. The motor has a new radiator and head. The only performance mods are 62mm TB and adjustable map sensor that I put on after I bought it. It also runs 4.56 gearing, a snorkle, borla headers, and an open exhaust with just a flowmaster 40-no cat. The trans has always hard shifted at high rpms since I got it. I replaced the fluid and filter. I also added a bottle of lube guard at the time as I do with all my trans fluid changes. It has always been slow to engage reverse since day 1.

my 95 does the same thing. hesitates to up shift and lags for a second before going into reverse. It has over 247,000 on it and i dont know if its original or not. I changed the fluid when I got it and it was better for about 200 miles then went back to doing the same thing. Its not my DD so I just deal with it. One of my hondas has a auto and when it starts shifting sloppy, a trans fluid change makes it happy.. Go figure.

Rammin97 said:

my 95 does the same thing. hesitates to up shift and lags for a second before going into reverse. It has over 247,000 on it and i dont know if its original or not. I changed the fluid when I got it and it was better for about 200 miles then went back to doing the same thing. Its not my DD so I just deal with it. One of my hondas has a auto and when it starts shifting sloppy, a trans fluid change makes it happy.. Go figure.

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The upshifts are strong and not sloppy but the shift points are too high in my opinion. Half a pedal of acceleration shouldn't take the rpms to 4000 before upshift from 2-3. Again 1-2 is about right and 3-4-od seems about right.

i am no transmission expert. but what you described sounds alot like a faulty pump or line blockage. maybe see if any of your local transmission shops will test the pump pressure for a minimal fee.

^this.

Thanks