I am trying to diagnose intermittent stall in my 1995 xj6 (X300). The car used to run very poorly, I did the flw:

1. Welded the cracked exhaust manifolds, refit with new gaskets
2. Installed proper champion spark plugs
3. Replaced fuel filter
4. Flushed the engine oil
5. Reset the TPS calibration
6. Replaced the old dead battery with a brand new Optima AGM battery.

Now the car runs quite well, except it occasionally stalls. It happens intermittently, seemingly at random.

The stall always happens when the car is stopped and in gear, for example idling at the light. It always happens in stop and go traffic, after the car has been driven for a while. Sometimes the RPMs drop, but the car does not completely stall, the RPMs go up and it recovers. It feels like an intermittent electrical problem.

In at least one case ABS light came on during the stall, but went away after I turned the ignition off and on to start the car again. The ABS light used to turn on at random when the battery was weak. It does not turn on any more, except for this once instance during the stall.

I also noticed that at the time of the stall (or an attempted stall) the voltmeter needle shows a drop in Voltage. I am not sure what the cause-and-effect relationship here is?

Also, when I shift into Reverse, the voltage seems to drop, then recover after a second or two. When I ship into Drive the voltage does not drop as much. In any event, this does not seem like normal behavior. I am suspecting that my alternator might be misbehaving, but I don't see the usual alternator symptoms. For example the brightness of my lights does not change as RPMs go up.

 

How did you "reset the TPS calibration"? I thought that took Jaguar service software?

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I had someone with IDS do it for me.