Well, it's been a wonderful, trouble-free run in the Daimler for a while now, so something like this was probably inevitable. Long story short, the car is stubbornly refusing to start at the moment, and I would appreciate any advice on how to fix this. Long story goes something like this...
Last Friday, I started the car up, and the idle was rough, to say the least. It slowly rose to fast idle, but was constantly dipping down to almost stalling before picking up again. Gently pressing the accelerator just made stalling more likely. But, I was able to reverse it out of the driveway, and after a couple of minutes all was well - idle was sound, accelerator didn't cause any nastiness, so I took it for a drive without any drama. Smooth all the way, like nothing ever happened.
Fast forward to this morning, in the usual Monday rush to get to work, and the same symptoms as Friday. It took a few spluttery attempts to get the car to idle, and when it did, it was uneven, dipping down to almost stalling again. So I thought I'd leave it the couple of minutes (like Friday) and had a coffee. I entered the (open) garage to clouds of fumes, to me it smelled (and looked) like incredibly rich running. The accelerator wasn't helping, so I decided to turn the car off, and take the XJS instead. Thankfully, that car ran beautifully!
Tonight I get home, after pondering on this all day. My first guess was maybe the good old Marelli rotor (cap was replaced with OEM only 12 so months ago), or perhaps the coils. I get home, and try to start the car - same result as this morning so I turn it off. I remove the cap, inspect the cap and rotor, but bar a few scorch marks on the points, all presented well. No burns, no damage to be seen, so I put it back together. I try to start the car again - it maybe seemed a little better (could be my own wishful thinking), but was far, far from good. I turn it off again. I disconnect both coils, and check resistances - primary resistance on the A coil was 0.8 ohms, and on the B was 1.1 ohms; with secondary resistance at 5k ohms (A) and 4.8k ohms (B). Now I couldn't find any specs to check these against, but given that both are similar, unless both coils have failed simultaneously, I am assuming that they are serviceable. Now the weirdness - I reconnect coils (noticing a little electrical cable insulation breakdown at the coil plugs to the primary connections, but the wires seem good), and try to start the car again.... nothing, no rough idle, no spark at all (or so it seems), just smooth cranking and lots of clattering (maybe the injectors, but I didn't listen closely), with a strong fuel smell from the tail pipes. I wait an hour to make sure it isn't flooded - same. No spark at all.
So, I am over to your collective wisdom, and I'll post this same issue in an XJS forum for those 6L guys. Are those coil plugs a likely culprit (perhaps removing and reattaching them caused some breakage), should I be looking at those ignition amplifiers, are the coils out of spec and have both failed, should I check a sensor (CPS maybe) is it likely to be a fuel issue, or (god forbid) an ECU fault? I should also note no VCM codes throughout this whole saga.
In the meantime, thank god for the simple old 5.3 HE...
1985 XJS HE (manual conversion)
1994 Daimler Double Six (XJ81)