XJ XJ8 / XJR ( X308 ) 1997 - 2003

limp mode after transmission swap?

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  #41  
Old 12-20-2023, 10:37 PM
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Originally Posted by ericnunez
How does this one look? Ebay It has 75k miles
The TB shown is for earlier AJ26 engines, not suitable for your AJ27.

Originally Posted by ericnunez
Or, this one? It's a refurbishing service.Ebay
The TB shown is for AJ27.

The two different TB-s:
AJ26


AJ27


Before you buy another TB, your mechanic should check and verify that the PPS is indeed bad and that you problem is certainly not due to loss of continuity in any of the wires connecting the PPS to the ECM.
 
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Old 12-21-2023, 08:25 AM
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I can verify from experience that if the petal position circuit is faulty, the car will complain about transmission problems and go into limp mode. I tried everything, including changing the transmission as it was intermittent on my car. Finally cut the petal position connector off and soldered one from a junk yard into the harness which ended the problem after about two years. Perhaps since the throttle body was removed to replace the transmission, the connector is faulty? If it has not been done yet, try cleaning it before you fool with anything else.
Good luck with your car!
 
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  #43  
Old 12-21-2023, 11:04 PM
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Originally Posted by David N. Warner
I can verify from experience that if the petal position circuit is faulty, the car will complain about transmission problems and go into limp mode. I tried everything, including changing the transmission as it was intermittent on my car. Finally cut the petal position connector off and soldered one from a junk yard into the harness which ended the problem after about two years. Perhaps since the throttle body was removed to replace the transmission, the connector is faulty? If it has not been done yet, try cleaning it before you fool with anything else.
Good luck with your car!
Thanks for your reply! And yeah, to be honest I'm not entirely sure the mechanic thoroughly checked the PPS and wiring to the ECM. Not to mention the fact that he said he never even touched the TB. I'm confused over here because if I'm not mistaken, the TB almost certainly has to be removed for a transmission swap correct?
 
  #44  
Old 12-23-2023, 11:04 AM
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Originally Posted by ericnunez
Thanks for your reply! And yeah, to be honest I'm not entirely sure the mechanic thoroughly checked the PPS and wiring to the ECM. Not to mention the fact that he said he never even touched the TB. I'm confused over here because if I'm not mistaken, the TB almost certainly has to be removed for a transmission swap correct?
I have changed a number of transmissions and cannot think you could do that with the throttle body in place. Perhaps it's possible but would be a real ordeal to remove the top transmission bolts.
Merry Christmas!
 
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  #45  
Old 12-23-2023, 12:13 PM
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When I started working on these cars almost 12 years ago, the first 2 cars of replacing the rear main oil seal I did pull the TB off. After that I got a long extension and just removed the rear transmission crossbar and lowered the backend of the transmission down enough to put the long extension and socket up to the top transmission bolts. I’m going to say they touched the TB and that was enough to upset it is my take on it.
 
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  #46  
Old 12-24-2023, 09:43 AM
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Originally Posted by Addicted2boost
When I started working on these cars almost 12 years ago, the first 2 cars of replacing the rear main oil seal I did pull the TB off. After that I got a long extension and just removed the rear transmission crossbar and lowered the backend of the transmission down enough to put the long extension and socket up to the top transmission bolts. I’m going to say they touched the TB and that was enough to upset it is my take on it.
They must have messed with it. The mechanic keeps swearing he did not remove the TB or touched it, but as I mentioned before, the codes were not there. As a matter of fact, I only had the "Incorrect gear ratio" code, not all these other three codes. Nonetheless, he says the wiring to and from the PPS to ECM is intact, and that the pins on the connector to the PPS are perfectly fine. I don't think so, and I'd like to check for myself, I just don't know whether or not I'd be able to check them myself.
 
  #47  
Old 12-24-2023, 11:27 AM
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I just did a rebuild of the 5hp24 and did not remove the TB. I would not say it was easy to access the top bellhousing bolts, but once the cats were out and a few things unplugged, I could reach up around either side of the transmission. I don't remember them being all that bad or what all combination of tools I used, but I've got a plethora that I've assembled over the years for the express purpose of removing and reinstalling inaccessible fasteners. But everybody approaches a repair differently. If you dismantled it a different order, say starting from the top down, you'd be inclined to remove the TB.

But I've had things not work after R&Ring engines before and found that it often is an electrical connector that I've forgotten about and left unplugged or didn't get fully seated when I put it back together. At the age of these cars, all the plugs are as crispy as water crackers. Sometimes have to use a dab of RTV, a ziptie or jury-rig some other way to hold connectors together upon reassembly. No doubt your mechanic snapped at least one plug retaining clip during the transmission out. I can almost guarantee it! Whether that's the problem or not, I don't know, but that's been my experience. I'd sure double and triple check all the electrical plugs before firing the parts-cannon at it.
 
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  #48  
Old 12-24-2023, 12:18 PM
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Originally Posted by pdupler
I just did a rebuild of the 5hp24 and did not remove the TB. I would not say it was easy to access the top bellhousing bolts, but once the cats were out and a few things unplugged, I could reach up around either side of the transmission. I don't remember them being all that bad or what all combination of tools I used, but I've got a plethora that I've assembled over the years for the express purpose of removing and reinstalling inaccessible fasteners. But everybody approaches a repair differently. If you dismantled it a different order, say starting from the top down, you'd be inclined to remove the TB.

But I've had things not work after R&Ring engines before and found that it often is an electrical connector that I've forgotten about and left unplugged or didn't get fully seated when I put it back together. At the age of these cars, all the plugs are as crispy as water crackers. Sometimes have to use a dab of RTV, a ziptie or jury-rig some other way to hold connectors together upon reassembly. No doubt your mechanic snapped at least one plug retaining clip during the transmission out. I can almost guarantee it! Whether that's the problem or not, I don't know, but that's been my experience. I'd sure double and triple check all the electrical plugs before firing the parts-cannon at it.
Hmm. He did mention a retaining clip being broken, but I don't recall which one. He then went to explain that the connection was good nonetheless. Wouldn't it have to be snag tight for it to actually work?
 
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Old 12-24-2023, 01:30 PM
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Originally Posted by ericnunez
Hmm. He did mention a retaining clip being broken, but I don't recall which one. He then went to explain that the connection was good nonetheless. Wouldn't it have to be snag tight for it to actually work?
Not necessarily but, it’s definitely preferable. Zip ties and RTV can be your friend with this. Unless from day one when the car was built and put into a climate controlled environment, there’s absolutely no guarantee that a connectors lock will stay connected after being unlocked. These cars are just old now and anything is possible. However, many of the electrical connectors are available new. I know the TPS connector is available. I don’t know if the PPS connector side of the TB is available. Does anybody know??
 
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Old 12-24-2023, 01:48 PM
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Originally Posted by Addicted2boost
Not necessarily but, it’s definitely preferable. Zip ties and RTV can be your friend with this. Unless from day one when the car was built and put into a climate controlled environment, there’s absolutely no guarantee that a connectors lock will stay connected after being unlocked. These cars are just old now and anything is possible. However, many of the electrical connectors are available new. I know the TPS connector is available. I don’t know if the PPS connector side of the TB is available. Does anybody know??
At least for the 99 and older cars, yes. It's a 5 pin toyota/denso maf connector, same as our mafs
 
  #51  
Old 12-24-2023, 11:28 PM
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Below is an extract from my compilation of connectors used on other cars that are also good for use on X308 AJ26. The full document, also containing other connectors, is attached as PDF which also contains hyperlinks to websites (but you can also search the web or Ebay by connector descriptions).

 
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  #52  
Old 12-28-2023, 12:34 AM
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Hey guys sorry for the delay, I've been busy with the holidays as I'm sure we all are. I'll probably be able to update on the Jag until January. Until then, Merry Late Christmas and Happy New Years to everyone reading this.
 
  #53  
Old 01-04-2024, 12:29 PM
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Default Update.

Hello all, hope you had a wonderful Christmas and New Years. I've just spoken with my mechanic and he insists the whole throttle body be replaced. I'm still quite sure they have messed something up while replacing the transmission, but for now the only option is to just buy the part.
 
  #54  
Old 01-05-2024, 08:41 PM
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Okay, I've now got a new PPS with a 3-year warrant, it's not Denso, which sucks but a three year warranty isn't too bad. I've also got a used TB in case simply swapping out the PPS isn't enough. Is this good?
 
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Old 01-05-2024, 10:56 PM
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Did the used TB come with the new PPS? Did it come with a TPS on it?
 
  #56  
Old 01-05-2024, 11:02 PM
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Originally Posted by ericnunez
Okay, I've now got a new PPS...
Interesting, where did you find it? Toyota PPS sold on Amazon looks very similar but its rotation is in direction opposite to that of Jag's PPS. Perhaps it can be modified to work on the Jag but, so far, no one has reported success.
 
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  #57  
Old 01-06-2024, 01:10 AM
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Originally Posted by Addicted2boost
Did the used TB come with the new PPS? Did it come with a TPS on it?
No, it comes with it's own used TPS. I purchased the new TPS to see if replacing only the TPS fixes the issue, and I can save myself $300.
 
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Old 01-06-2024, 01:11 AM
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Originally Posted by M. Stojanovic
Interesting, where did you find it? Toyota PPS sold on Amazon looks very similar but its rotation is in direction opposite to that of Jag's PPS. Perhaps it can be modified to work on the Jag but, so far, no one has reported success.
Ebay, but what year and model for Toyota's PPS?
 
  #59  
Old 01-06-2024, 01:59 AM
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You can see the Toyota PPS offered by a number of Amazon sellers if you google "Laformo Pedal Position Sensor" then click on "Images" for easier navigation. It is sold for Toyota Lexus, Tundra and Sequoia.
 
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  #60  
Old 01-20-2024, 09:12 PM
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Default Update:

Bad news. After replacing the entire Throttle Body and PPS, the car remains with the same fault codes. Limp mode is still on and there seems to be no improvement. The mechanic kept apologizing for not being able to fix the car. It's been nearly three months now. I took the car to him in November. I'm thinking that it's a cable/connection issue. I feel like I'm so close to fixing it to give up now. What can I do now?
 
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