XJ6 & XJ12 Series I, II & III 1968-1992

New MeMbe!!!

Old 01-08-2008, 09:58 PM
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Default RE: New MeMbe!!!

Hello there and welcome to the forum. 40K on an 83...Nice!
Old 01-16-2008, 07:06 AM
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Default RE: New MeMber!!!

I have a 86 XJ6 VP, and when its cold out(20F-39F) i get 6-8 MPG, when its warm (50-70F) i get 15-17 MPG, Thats just going by what the computer says on the dash. Im not sure if thats 100% correct since its a 86 old school computer in the car.
Old 01-16-2008, 07:17 PM
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Default RE: New MeMber!!!

as long as we are talking Series III XJ-6, (1980-1987 USA market), then each car is different from the other, because they were hand assembled, hand-tuned, hand-this, hand-that.

Don't even bother with the "computer", it is not accurate.

A fair miles per gallon is 18-21 mpg. And even then, some cars are more efficient than others.

In long trips, highway/interstate driving, I can get 525 miles out of the twin tanks of my 1984 XJ-6 before having to stop to refill. I think that's pretty decent for a Jaguar. Also I am talking setting it on Cruise at 70-72.5 miles per hour. Any more than that and gas mileage goes down.

also I keep fresh oil (Castrol 20W50) and filter in the engine. No burnt oil.

also I keep the tire pressure at 33 psi.

I use Splitfire SF6E spark plugs.Gap at .035. I use a K & N air filter.Andbecause mine is of the older XJ-6 with the single-wire Oxygen Sensors, a Ground Strap was added from the sensor to the body. Why?

It is a well known issue that as these cars get older, the Grounding becomes less effective, the Engine Control Unit (ECU) gets a less and less "positive" signal from the Oxygen Sensor, causing the engine to be morethirsty than when it was new. It's trying to "catch up".

In my car, the result from adding a O2 sensor Ground Strap was inmediate:a more stable idling, and better gas mileage. If your car has the TWO or THREE-wire O2 Sensor, you don't need a ground strap. The only engines that benefit are the ones with SINGLE-wire sensors.

If any of you with the older XJ-6 (1980-1985) wants a nicely made ground strap, contact me.

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