Hi guys, I am new here and have recently bought a fabulous X type.
The car is in mint condition and having just come up to 60k I did the major service plugs, filters, and all fluids incl auto box, transferbox, and diff.
The car runs just fine and there are no fault codes, however I have one very annoying fault.
When in 4th or 5th gear above 40 mph, if I lift off there is no discernible engine braking until 4-5 secs later then you feel the car lurch and then it starts to slow as you'd expect due to the throttle being closed. I will say now that the rev counter is stable and only moves when the box drops a gear, so I believe the lock up function is working correctly, however I've never had an automatic before.
I have checked that the throttle plate is clean and responding to the gas pedal correctly.
Its as though the throttle isn't closing when you lift off, then suddenly shuts a few secs later giving the shunt or lurch, it feels like there is lots of slack in the driveline as you can feel almost the same shunt when you step on the gas but it is immediate, there is absolutely no slop in the drive line as I've been through it end to end and it doesn't do it in 1,2,3.
Could it be a lazy lock up solenoid in the box that is not responding as quickly as it should, although I would have thought the rev counter would reveal that by dipping then going up again as the converter locks the box to the engine.
A guy on the UK forum had the same symptoms and his was cured by changing one of the upstream O2 sensors, but he also had the CEL on, although I can't figure out how a duff O2 sensor would give this problem as the engine is on overrun and there is no fuel being injected, mine has no CEL and just shows P1111 on the code reader.
I would be really grateful if anyone has any ideas as its a real PIA and makes it look like you are a really sloppy driver. Maybe this is completely normal on this model as I haven't driven any others to compare it, but I feel its only done it since I serviced it a week or so after I bought it. I did tons of research to find the right auto fluid as I knows its critical on this box, could the oil spec be not good enough as I bought an synthetic atf alternative to Jags own oil. The dealer wanted $550 to change the auto fluid!
Thanks in advance.

 

Norcat, from what you are describing, it sounds like what you are experiencing is the torque converter unlocking after the car has been coasting for a bit. The car does this normally on a coasting situation to try and let the car coast a little further.

Something you can try when on a road all by yourself. Get the car up to 60 MPH (100KPH) and keep your foot on the gas pedal to maintain speed but also apply the brake slightly (really just enough to light up the tail lights). You should see the engine RPMs jump up a little bit when the tail lights come on. Did you get the same sort of jerky feeling? If so, then you are probably just feeling the torque converting unlocking on a coast.

 

Thanks Thermo, that sounds logical, I will give a try next time I'm out.

 

Hi Thermo, I tried your suggestion today but it only seemed to work when in 4th gear. When you say unlocking I guess you mean the converter is no longer mechanically locked to the gearbox so the revs can float free of road speed, whereas what happens feels like the exact opposite, it feels as though the converter is free after liftoff and a further 4-5 secs later the converter then locks as you definitely feel engine braking coming on, just like a downshift except it hasn't shifted down according to the rev counter. However as I understand it, if the converter was unlocked at liftoff the revs should drift down whereas lockup will keep them where they were at liftoff same as a manual box. Confused? so am I.
Its a very obvious lurch as my wife often looks over and says was that you or the car?
I wonder if anyone else's auto does this, or do I really have a fault brewing.

 

NOrcat, you have me then. I am not sure what is going on. This is probably something that should be taken to a shop to be inspected. It does sound like the torque converter does have some sort of issue, but maybe it is something that can be easily fixed.

 

Problem is there are only 3 dealers in the whole country, one is in my town but have only been a dealer a few months and their guys know less about the car than I do!
I will try to find a transmission specialist as at least they will know how the box should work.