'87 XJS V12. I serviced my rotor and now the car is running rough and rich.

Last weekend I removed the distributor cap and checked the rotor. Everything was perfect: 11 degree counter clockwise free movement with springy metallic clink return. Refreshed cotton like wadding in shaft center with synthetic 20-40W oil. Anti-flash shield in perfect shape. 10+ years ago a friend and I serviced his two Jags and mine after learning about the potential stuck rotor issue in the Kirby Palm book. We removed complete distro units from all cars, cleaned them of all old gunky "stuff," Shaft lubricant changed to synthetic oil, re-installed and timed by the book. All were better than new.

I re-installed the rotor in the same position it was when I took it off, put the cap back on with both vent hoses connected, re-connected all plug wires in proper sequence following the chart to the letter. Connected battery cables and started car. Running, rough, high idle at 1000 rpm, and very rich. (Good news is houses in my immediate area are now Zika free). Only hose not connected was cruise control vacuum (I did note that it does not seem to have much vacuum pull when the motor was running). No change to the motor was noticed when I plugged the hose with my finger. Motor did not smooth out when I increased rpm by twisting throttle tower.

Suggestions and advice welcome.

 

Lucas or Marelli? But my first thought would be to check the injector loom, which you could have disturbed and got a group or two of injectors shorting and thus staying open and making the car rich. Essentially, injectors malfunctioning is about the only way these cars can run rich. I suggest you remove the loom and inspect it carefully for cracks etc.
Greg

 

Greg,

Its the Lucas system. By injector loom are you referring to the electrical harness to the injectors.

My longer term goal is to go all the way down to remove and clean the injectors; remove the air injection system and plug the holes; polish the fuel rail, injector retainer plates, and cross over pipe; and install a "Quick Cat" air intake system to replace the stock (and too restrictive) system.

 

Yes, the wires that go to the injectors and plug into the main system behind the RH headlight nacelle. There is a very knowledgeable professional guy, Safari, from Denver Colorado, who is making a run of new injector looms. If you find yours is shot and do not fancy making one yourself, you could PM him. They are NLA from Jaguar.


If, in the meantime, your loom is cracked, you could CAREFULY strip the outer wrapping, and then using tape equally carefully reinsulate each actual wire, and then rewrap the wires. This should keep you going.
Greg

 

Not that Greg's advice ever needs reinforcement from the likes of me but, FWIW, I agree that the injector harness was likely disturbed and damaged...or perhaps the coil wiring.

This isn't a criticism of your work (or anyone who works on an old V12). The tangles of wiring become brittle; it's virtually impossible to avoid damaging the insulation

Cheers
DD

 

Good point about the coil wiring Doug, that could easily cause the trouble if the coil is not firing properly.
Greg

 

Mine did exactly the same thing last year. It was my distributor cap. (After I changed the fuel pressure regulators, CTS, ATS and their plugs, ignition amp). How old is your cap? Make? Remember these things get hot in the "V" and that cap doesn't take kindly to the heat cool cycles then being "disturbed" by removal/re install. Not saying that's it but it sure sounds similar to my problem last year. Mine would rev great above idle in "P" or "N" but would idle like crap, miss and run rich and wouldn't accelerate worth a damn in "D"

 

Good point too. Lots to check, but the cap HAS been disturbed so well worth checking/replacing anyway.
greg

 

dear, dear, the wire to one of my coils... the plastic insulation had just fell off and the wires were simply just bear copper running to the coil...
liquid electrical tape did it for me (temporary fix)
I did not know there was even a liquid electrical tape... cool stuff!

carefully look at your wires...