2006 XJ8L 215K transmission seems to be "slipping" on the highway from time to time. Seems to happen most often on very slight uphill grade at moderate speeds, a little bit of throttle to increase RPM seems to satisfy this gremlin. other times under non-aggressive load we can feel the same slip shudder. seemingly no problems with harsh acceleration from stopped or at speed (passing). the shift from 2-1 may be harsher now but I can't be certain and it is not all the time. I did a filter, sleeve, fluid change less than 10K miles ago with LG6 and ZF filter and sleeves, and have checked the fluid level as best as I can with the knowledge from this forum. I wish I had done the solenoids at the time, but wishes don't amount to much. I get no codes from the TCM on either of my scanners that communicate with it. Is there anything I can do to check solenoids or anything else if they don't "throw codes". I have IDS/SDD V130 from British Diagnostics but I am somewhat hesitant to
flash the TCM. This may be the ninth life of this Cat so some things are off the table.

 

A few years ago I had a bad experience with a diy job on my car so I took it to

a g'box specialist to have the plastic sump replaced with a proper metal one.

Nice guy just him and his son.

Anyway I asked him "if you have solenoid problem-how do you know which one is faulty?

He said "my scanner will tell me"

 

I had identical symptoms when my fuel rail pressure sensor was going bad. Almost without fail any time I was under slight load the engine would surge like it was a slipping transmission. Only real clue was fuel trims, which would spike during the "misfire". A new FRP sensor fixed it.

 

Interesting ....I will investigate that....I have replaced that sensor before, but the periodic fuel rail pressure code continues to pop up from time to time. Misfires don't seem register however. Perhaps I will need a someone to drive while I monitor live data.

 

Your reader just may record your readings, on a graph type read out, many readers do

 

Here's the thread with more details from my issue: https://www.jaguarforums.com/forum/x...adings-195311/ It's a long thread, initially found a bad AIR sensor solenoid, then made an educated guess on the fuel pressure sensor.

 

Thanks for the link, much appreciated, it's a long read, but informative and thought provoking. I will digest it over the holiday weekend and start fresh next week. I previously replaced the ground stud behind headlight assembly on the passenger side, but have not addressed the driver side yet. Noting that I do have a markedly dimmer low beam on the driver side, it sounds like I should get on that as possibly related to this issue too. It also sounds like a thorough examination of O2 sensors wouldn't hurt either.

Thanks Happy 4th!

 

Well I have had a chance to put multiple scanners on to check the fuel pressure readings. I am somewhat confused as there seem to be two separate fuel pressure readings available to all three scan tools. I get readings of ~38psi and ~55psi respectively and consistently across all scanners (iCarsoft, Autel, and SDD/IDS) for the separate fuel pressure readings. Oddly, I am also getting a reading of ~80 volts as the "fuel pressure sensor voltage". Again consistently across all three scanners. P0193 is persistent. Any thoughts on the two fuel pressure sensor readings or the 80 volts reported at the sensor? I tried disconnecting the FRPS while idling, the engine stalled after a few seconds.

 

If not done already, change rectangular "bridge seal", round seals, solenoids and maybe some other stuff like pan and oil.
Best to buy a reman valve body from a reputable seller if you wish to keep the car.

https://www.bavlogic.com/?p=3738

Basically, because of leaks or dirt blockages, the control body can not supply the correct pressure to hold the clutches properly. So its like accelerating in a manual transmission with you foot pressing half way down on the clutch.
Or your problem may be something completely else.

 

Tigre, bridge seal, round seals, pan/filter and connector seal all replaced last year, maybe 10k miles. I did not do the solenoids at the time. Scanner report normal for all the solenoids as far as I can tell. Fluid level checks out. no codes except P0193 pop up....

 

Could it be issue with the locking of the converter?
Im not sure what in what speed you are having this issue, and I dont know what the speed needs to be for the converter on theese car to lock.
Ive hade this issue on several cars (Audi a6 and a8), both times the converter was bad

 

UPDATE: Thanks to all for the suggestions. I decided to give a new (after market) fuel rail pressure sensor a try to see if my crazy 80V reading would change. It did not, and about one minute after starting the engine stalled and would not restart. In that minute the new pressure sensor must have ruptured and sent fuel streaming into the throttle body. I reinstalled the old sensor (Standard -FPS17) but I am still getting some wonky readings for the fuel rail pressure sensor voltage at 80+V but the pressure seems fine at roughly 55PSI, and the jerking still appeared, perhaps worse than before. I took the car for a drive, with scanner recording. I was finally able to "catch" the culprit misfire on the scan tool while driving. #5 coil was bad. Since then all seems good. I am still not sure what the second fuel rail pressure reading is. At 38PSI, I suspect it could be a fuel transfer pump in the tank? I can not explain the 80V either.

 

The 80V is from a faulty tool.

 

I thought so too, but I get 80 volts on all three scan tools, Icarsoft, Autel, and SDD/IDS. Seems unlikely that all three would be faulty....and show the same voltage. It is not steady pegged at 80V, there is some +-0.1-0.2V fluctuations. I'm not losing sleep over it as it doesn't seem to effect anything. Just a head scratcher, but as a novice, I find plenty of itches to scratch. Any thoughts on the second fuel pressure reading of 38PSI?

 

i’m at the same mileage, when it had a miss it would rubber band and shift like garbage. if it’s your eclutch you’ll have hard 3-4 4-5 shifts and eventually a p0783


use a genuine jaguar/motorcraft fuel rail pressure sensor

 

The 80V obviously isn't true so I suppose other possibilities are:
1. the car returns a daft value
2. each tool uses the wrong internal logic
3. it's an unsupported value, or used for something else, thus #1

I've never had any use for the reading so for all I know lots of cars do the same. I would ignore it.

38psi sounds odd but I don't have your car & engine.