last year I bought a 1981 Jaguar XJ12 V12 Vanden Plas car was made in Febuary of 1981 and I don't think it's HE, has 60,000km the guy I bought it from was either in the process of or finished installing a Crane Cam (XR700) ignition (from summit racing) he said he couldn't get injector pulse. I picked it up about a week later and he had managed to get it running by running a wire that goes from the coil to the ECU. The car now runs way to rich if I have it running (outside) my eyes water from the exhaust I stopped running it after I found it was running so rich that I think there was gas in my oil and the chrome bumper had soot on it. I need help would it be the ignition doing this why does it run with the wire but not without? Thanks in advance

 

You may want to post in the XJS forums, there are more V12's over there. You also may want to find someone who knows these engines locally.

 

Impossible as I live in a small city and no one has even touched one of these around here

 

HE ? or Pre-He? identification was discussed in this thread.

https://www.jaguarforums.com/forum/x...daches-134180/

But, either way, a few things to check for rich running.....

1) coolant temp sensor giving a 'cold' signal to the ECU when the engine is actually warm

2) leaking fuel pressure regulator (or regulators) allowing raw fuel to be drawn into the cylinders

3) faulty pressure regulator allowing excessively high fuel pressure

4) leaking fuel injector(s)

5) injector harness fault causing a grounding-out....which would hold injectors open

6) electric and or vacuum "full load enrichment switch" stuck closed, causing rich running (not sure if pre-HE would have these switches)

7) vacuum supply line to ECU broken/disconnected (not sure if pre-HE would have this)

That oughta be enough to get the conversation going. Others will chime in with more

Cheers
DD