I just had a transmission installed in my 2000 XJ8. The $1500 job turned into a $3700 job. I do not think it is running right but the mechanic says it is okay. When cold 2000rpm will drive at 80 KMH when it warms up 2000RPM drives at 100 KPM. He says it is normal. I never noticed it before in the car and I have been driving it 5 years. Fuel economy is down and passing gear is not the same. No power. Kicking it down in sport shift mode does not sink me down in the seat near as much and it will redline the engine. Do any of the members know what I can say to the mechanic? He says it is normal for a locking converter or it just has to wait for the transmission computer to understand the way I drive. ?????? Never heard that one. The heater in the car does not work either if that helps with the diagnosis.

 

If the car drives very differently now & you say it is behaving worse, then something is not right. Without the correct diagnostic equipment, your gearbox behaviour since the repair cannot be easily traced to a particular fault.

As it's now going to be 'your word against his' with the mechanic, you'll need an independent assessment of the gearbox behaviour since the repair. You could either ask an official Jaguar dealer to check the gearbox behaviour & provide you with a written report-or take the car to an official ZF transmission agent for them to check the gearbox operation.

Quite a few automatic cars hold on to the lower gears longer when cold to keep the engine speed high-this warms the catalysts up more quickly to the 'light off' point where they start to work.

However, once the engine & transmission are warm then performance should be the same as when you had the car for the previous 5 years-if it's now slower to accelerate & using more fuel, then something's not right.

Due to the size of your repair bill, it would be worth having a proper gearbox behaviour assessment done by either Jaguar or ZF & getting an official report to present to the mechanic who repaired your transmission-otherwise he's not going to budge & won't listen to you alone.

You need to have an assessment done to check the exact speeds that the gears change up (or down), at various throttle positions & also for the operation of the torque converter lock-up clutch. Jaguar & ZF should have this information-although the gearbox ECU will be programmed with Jaguar's speeds & throttle positions for the various gearshift points, so your first port of call should be to a Jaguar dealer for a proper diagnostic check.