I just bought a 2003 xj8, and when I get up to speed and it shifts into 5th and the rpm drop to around 1600 it shakes badly. If I manually put it back in 4th and the rpms ride above 2000 it goes away mostly, but it still there. I can also notice it when accelerating hard but it is most noticeable shifting into 5th when the rpm are lowest. What would this be? I just replaced plugs, coils, and injectors and have no engine codes on at all so no indication there what it may be. Thanks!

 

My first question would be have you recently or ever had the transmission serviced? Fluid/Filter change.
I would suspect that there is a transmission problem. Possibly low or burned fluid and the torque convertor is not locking up. To check the fluid you have to have the gearbox warm and remove the fill plug. The you should have a small drip from the plug opening. If no drip you are low and need to add fluid.
To get the codes read you would have to take it to a dealer or an independent garage that can read the trans module for stored codes.
Another possibility. One that you can visually verify is a bad motor mount. Lift the hood/bonnet and start the engine. With the transmission in gear and your foot on the brake raise the rpm above 1500. Observe the engine does it lift slightly (normal) or does it lift considerably? A significant movement of the engine lifting would indicate bad motor mounts.

 

When I accelerate from a stop I do get a gearbox fault error come up, mainly when the car is cold. It is very hard to accelerate and seems bogged down or restricted. It seems to go away when the car is warm and I run it. Would this indicate that it is a problem with the torque converter for the gearbox fault message and the shaking?

 

Post #2 looks good.

 

I just brought the car to a shop to have the tranny fluid filled and they said it was already full. Anything else that could be causing it?

 

I have had this problem with the early GM 4 spd automatics and it was always the torque converter trying to lock up. Does it do the same thing in sport mode?

 

Hi Brummel1,

Welcome to the Jaguar Forums! It's great to have you with us.

The gearbox fault is an important clue, but typically it will flag at least one Diagnostic Trouble Code (DTC), but you don't have any. Sometimes the gearbox fault can be caused by low battery voltage or low voltage at the Transmission Control Module (TCM).

One suspect that occurs to me is the transmission fluid. Vern mentioned that it could be burned, but I would have expected the transmission shop to notice that. What they might not have noticed is if the fluid is the wrong type. Your ZF 5HP24 transmission requires a specific type of fluid to operate properly. If the previous owner had the gearbox filled with incorrect fluid, say one of the more modern low-viscosity fluids, your torqure converter may not be able to lock up.

The fluid specified by ZF, the transmission manufacturer, is ZF LifeGuard 5 meeting the ESSO LT 71141 specification. There are several good lower-cost options that also meet this standard. Here's the list of known-correct fluids:

ZF Lifeguard 5
ESSO LT 71141
Mobil LT 71141
Febi Bilstein Automatikgetriebeöl (ATF) nr. 29738
Pentosin ATF 1
Ravenol ATF 4/5 HP

Automaker-branded packaging of ESSO LT 71141:
Jaguar JLM 20238
BMW 8322 9407807
BMW 3 22 2 220 442
BMW ATF 71141
BMW LA 2634
BMW ATF-1
BMW ATF-4
Citroen Z 000169756
Mercedes Benz A 0019892203
Mercedes-Benz 236.11
Peugeot Z 000169756
Porsche 999.917.547.00
VW/Audi G 052 162 A1 / A2 / A6
VW LT 71141

Another possible contributor to vibration under load could be a problem with one of the driveshaft flexible couplings, the driveshaft center bearing, or the transmission mount/rear engine mount.

If you have a scanner that can read Live Data, it would be worth watching your fuel trims for signs the engine may be running rich, or the Mass Air Flow Sensor (MAFS) signal out of spec causing the Engine Control Module (ECM) to improperly account for engine load, problems with the catalytic converters or oxygen sensors, etc. Typically those sorts of problems with flag codes, but not always, and often unusual behaviors like your Jag's are due to multiple causes.

By the way, please visit the New Member Area - Intro a MUST and post a required introduction so we can learn something about you and your Jaguar and give you a proper welcome.

Cheers,

Don

 

Well turns out google isn't always a reliable source, I had an engine misfire code on cylinder 6 and it turns out I replaced the wrong one, and didn't reconnect another one properly, which I noticed when an engine code came on again yesterday. Got a new one installed tonight, didn't get a chance to drive it but it seems to be running better. Hopefully this fixes the shuddering, with 2 cylinders misfiring that could have been the problem. Fingers crossed!