1995 XJS 4.0L coupe with 62,000miles

I have just had a problem pop up...Idle is "sometimes" rough and will occasionally stall. I noticed my odometer and trip odometer are intermittent. The tack and speedometer are working normally. The trip computer I installed about 4 months ago is keeping the correct mileage, gallons used, avg. speed, and MPG. Is there a separate speed feed to the instrument cluster for distance that is different from the trip computer source? Coming back from lunch Monday the car stalled several times but started up immediately after the stall. Then it went into Limp-Home mode, with the transmission warning light on and no check engine light. Leaving the office after work the transmission light was off and the car ran normal. It has stalled several times yesterday and this morning but there are no driving problems, I can feel. If I reset my trip odometer in the tack it will work for a while, as does the odometer in the speedometer, trip computer remains unaffected.

As a side note, the electric radiator fan is not coming on with the A/C as it once did. I think that is a fan motor issue, and not related to my stalling problem. However, “in bumper to bumper” traffic, driving temperature rises above normal almost half way betweenN & H.

Recent service includes cooling system flush, brake fluid flush, and transmission fluid and filter.

 

The speedo and the trip computer are both fed by a pulsed signal from the road speed interface unit. I'm not sure if the odometer is the old-fashioned mechanical style that works off a rotating cable from the transmission or if it is an electro-mechanical type that gets a signal from the ECM and uses a stepper motor to advance the odometer.

Unless you have modified the circuit, the electric fan is independent of the A/C system. It is only controlled by the thermal switch in the radiator. The switch is supposed to go off at 91C and on at 96C. Because of it's location about 1/3 of the way from the top of the radiator, coolant temps exiting the thermostat are about 100-103C before the fan switches on, this will show as about halfway between N and H on the gauge, however this is still in the 'normal' range as far as Jaguar are concerned. This pic shows my gauge just before my fan comes on.


Cheers,

Allan

 

Instrument cluster is electronic; there are no mechanical cables to the speedometer or tachometer.

Yes, the cooling system was changed to bring on the radiator fan with theA/C clutch.