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RustyTruckHoarder

Factory 2.5/aw4 nightmares.

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Hey guys, new to the forum. So I've had my 87 with the factory 2.5 and aw4 for about a year. I had no idea how rare it was until I had shifting issues. Turns out it is most likely my TPS. After I had tried a new TPS it didnt fix it. I then found out I was receiving the TPS for a 4.0. There has been absolutely zero aftermarket support for a TPS for a 2.5/aw4. I had to go to the dealer and have them search it and there was only 3 of then left in the continental US. I will find out tomorrow night if it in fact is the correct part. If it is, I will post the part number. I have yet to find any other supplier, though i find it hard to believe these 3 are literally the last 3 available new. If anyone has input on this, or a link to any aftermarket TPS let me know, also I am trying to keep track of all the part numbers of anything else that is hard to find. The torque converter for example crossed over to a TC for a volvo, and I worked. So I will relay any of these types of things that I can. Lord help any other 2.5/aw4 unicorn owners.

 

 

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So you got a TPS for the 4.0, what was the trans doing or not doing that makes you think the TPS was not recognized?

I'm not sure that the TPS is any different one from another. 

The only think I can think of what would be different is the shift points, and the bell bolt pattern, otherwise the TCU should be the same and should recognize the TPS. 

 


What was the engine doing?

 

 

 Aftermarket sensors suck, period. So, if the Mopar TPS works, it works because Mopar sensors work. 

 

You will also want to find a Mopar CPS. 

 

 What was the difference between the 2.5 and 4.0 TC? The 2.5 should have a higher stall speed. The fact that you found a Volvo TC to work is not at all surprising, there may be others. 

 

If there are three TPS, now two..........consider  yourself fortunate.......maybe you should buy another. 

 

You'll never find another flex plate either, protect the one you have. 

 

 

Parts are scarce. 

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The 2.5 TC has a different snout, and a 4.0L one will NOT work.  It will not fit into the opening in the 4.0 flex plate (it is both too long and too large a diameter).  I can't speak to the differences to the TPS between the 2 though....I can't see there being much, if any, difference.  Yes, you have a rare bird.

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15 minutes ago, Jeep Driver said:

So you got a TPS for the 4.0, what was the trans doing or not doing that makes you think the TPS was not recognized?

I'm not sure that the TPS is any different one from another. 

The only think I can think of what would be different is the shift points, and the bell bolt pattern, otherwise the TCU should be the same and should recognize the TPS. 

 


What was the engine doing?

 

 

 Aftermarket sensors suck, period. So, if the Mopar TPS works, it works because Mopar sensors work. 

 

You will also want to find a Mopar CPS. 

 

 What was the difference between the 2.5 and 4.0 TC? The 2.5 should have a higher stall speed. The fact that you found a Volvo TC to work is not at all surprising, there may be others. 

 

If there are three TPS, now two..........consider  yourself fortunate.......maybe you should buy another. 

 

You'll never find another flex plate either, protect the one you have. 

 

 

Parts are scarce. 

 Hey there, so what it did with this TPS was shifting at the wrong points, think of it literally as the TPS telling the trans to do the reverse of when it is supposed to hold a gear or when to upshift. When lightly on the throttle it will hold the gear, when you give it more throttle it will shift too early. I found after looking at schematics of how the voltage is read between the two sensors, is the 2.5 starts at 5 volts and goes down, the 4.0 does the exact opposite. Also if you look at the little lever on the TPS..... the 4.0 lever sits to the left side of the sensor, the 2.5 sits to the right. They are essentially mirrors images of eachother. From what I can tell, the sensors both plug in exactly the same, and after seeing how I had to finagle the 4.0 sensor in to get the lever to sit on top of the lever coming off the TB it makes me realize it isnt right. With it setting on it, it is sprung all the way back from its resting position. The 2.5 sensor will sit right under the level coming from the throttle body at the resting position. It seems much more correct.

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2 minutes ago, Colton Tyler said:

 Hey there, so what it did with this TPS was shifting at the wrong points, think of it literally as the TPS telling the trans to do the reverse of when it is supposed to hold a gear or when to upshift. When lightly on the throttle it will hold the gear, when you give it more throttle it will shift too early. I found after looking at schematics of how the voltage is read between the two sensors, is the 2.5 starts at 5 volts and goes down, the 4.0 does the exact opposite. Also if you look at the little lever on the TPS..... the 4.0 lever sits to the left side of the sensor, the 2.5 sits to the right. They are essentially mirrors images of eachother. From what I can tell, the sensors both plug in exactly the same, and after seeing how I had to finagle the 4.0 sensor in to get the lever to sit on top of the lever coming off the TB it makes me realize it isnt right. With it setting on it, it is sprung all the way back from its resting position. The 2.5 sensor will sit right under the level coming from the throttle body at the resting position. It seems much more correct.

Got it, thanks. 

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So, good news. I got the new TPS and it worked flawlessly. It was definitely sitting on the shelf at the dealership for a long time. But here is a picture of the box with the Mopar part number for anyone needing it. I will post pictures of the visible differences between the 2.5 and 4.0 sensors at some point. Hope this helps someone else out in the future.

20190306_190121.jpg

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