Close but not quite! You're removing the air filter, not the whole air cleaner assembly. Poor wording on my part, you're only removing half of the assembly.

Just pop the two clips on the black housing, and tip it back enough to get the paper element out. It might be pressed in tight, as there is a rubber seal around the edge, but it will come out. It takes some wiggling to get it clear of the AC hoses. It's easier to remove the outer metal half with the trumpet with the paper air filter out of the way. Then the trumpet half can just come out, there are 2 locating tangs on the bottom. That's all you need to remove to be able to see the exhaust pipe.

To reassemble, it's the reverse procedure. The outer trumpet portion goes back first, locating the tangs in the bottom of the housing bolted to the engine, and then the air filter goes in. Note that there is an arrow on the back of the filter that points to the front of the car, and the pleats should face out. It's not the easiest thing it the world to wiggle it back in, but it does go, then do up the clips and you're done.

 

Ah, I get it. You just need to remove the outer half of the assembly! Much easier, definitely! Okay, it's a sunny Saturday, my work is on track for completion on time, and this won't take long to check....

 

Okay, I've taken a look. Can't see anything amiss, but I can't trace the wires, either.
Getting the outer shell off was a stroll in the park, and much quicker. Noticed some soot buildup where the air pump...? auxiliary air...? (isn't that the port side?)... some rubber hose is connected up.


Well, there's the new O2 sensor all right--shiny and gleaming. However, the sensor ends under the engine, and I cannot see where the wires from it go.


From what I've read, they sort of wrap around the steering and then come up, so could this wire be it?


I can find two connector there. One has a bright blue wire coming out of the rear side. But they both appear to be connected normally. There's another connector towards the front of the car, under the windscreen washer filler pipe, that's also connected up. Nothing seems loose or missing.


So I wonder which of these is the heater connector.... Any suggestions or hints would be gratefully received, of course.

 

In your last photo, the one you have labelled as two connectors is indeed the O2 sensor connection. The one that's most visible (closest to the engine)is the heater wire, that should be a simple spade connection on a single wire. Maybe try pulling that apart to make sure the blade is making good contact Crimp the female side a bit with some pliers if the male blade slides in and out easily. The other connection is a Bosch style connection, and should be identical to the power connection to the fuel injectors. That's a 2 wire connection. As long as it's seated it will make contact. There is a small retaining wire on the female side of the plug that holds it together.

The sooty patch on the air filter is where air from the air pump enters the engine. On my 94, the air pump is electrically driven and runs for about 45s after a cold start.

 

Thanks again, Jagboi - I'll give the contact a clean with my contact cleaner, making sure it's all shiny and also fits together well, but not loosely.

 

Okay, I took a look. The male contact slid out easily but not loosely--I didn't need to yank it or anything, but it didn't fall out or anything. It's held in there pretty tight, so I didn't think I needed the pliers to squeeze the female contact tighter. It seemed basically as tight as it would have been when new.


It remains to test it, of course, but that will have to wait until tomorrow as I still have a deadline for today. But many thanks, Jagboi, for your guidance. (It's amazing how much room removing the outer cleaner casings opens up for working on the engine....)

 

Should be in decent shape then. You might want to test if there is voltage at that connection with the car on.

Sometimes there is some surface corrosion and just pulling apart and putting together the connection a few times scrapes it off and it's good to go again.

 

Could be. Looked very clean for its age, mind.
As for testing voltage, that's the tricky thing. I've looked in a number* of DIY shops so far, and cannot bloody find a voltmeter thingy. I cannot imagine such things are not available here, but damned if I know where. There are several places I want to use it. I should probably just look online I guess.
*That number is three so far. Including the biggest one in the entire region which carries enough to build a house, it seems. A metric tonne of electrical tools and gadgets, but volt testers? Bugger-all. I shall need to step up my efforts....

 

Sometimes they are called multimeters, or a DVM (digital voltmeter). If you want the best, the brand for that is Fluke - expensive naturally, and probably far more meter than you need, it's professional grade tools. Sort of like using a Leica for a once a year snapshot. A quick web search turns up Hoiki as a Japanese brand that look similar.

Are there any electronics shops that cater to hobbyists? Sort of the equivalent of what Radio Shack used to be like here? A search turned up some names of stores: 秋月電子: Akidzuku Dennshi, マルツ: Marutsu, せんごく/千石: Senngoku. Also the Akihabara Electric Town region of Tokyo(?). Not sure if that's good information or not!

 

Thanks for the research! Unfortunately, those places are nowhere near where I live. But under "multimeter" I found a number of ones sold on-line, so that's clearly the place to start. Probably don't need a Leica-type, no. Hoiki looks like a brand to start with. Don't think I need anything too fancy.
Thanks again!

 

Good luck in the quest to get the light out, that can be a tricky one to cure.

 

Thanks for a very detailed and interesting thread.My '89 XJS is due for the dreaded California Star smog inspection in mid December. It passed easily last time, so I'm hoping for the best. Good luck on investigation. I'll be keeping an eye on this thread.

 

Minor update: Took her out today, and for about 10 km all was well. I was starting to wonder if cleaning the already pretty clean heater connection was really all that was needed. Of course it wasn't. The CHECK ENGINE warning came on my trip computer. Naturally....

I'm still wondering about adding the extra earth leads as laid out in TSB 18-57 for the later six-litre, on the grounds that more earths couldn't hurt. However, I'm leaning towards it not being a connection/electrical issue at the moment. That's because on the way back from the university, just a couple of minutes on, waiting at the lights the engine stumbled and hiccuped again, and then the CHECK ENGINE warning came back on. There's clearly a connection there. Somehow, fuel isn't being delivered properly. That's my guess. From the stumble, I'd guess too little. Perhaps I should listen to the injectors again, though the spark plugs might not be perfect either (though they're less than two years old).

Another thing which makes me think "fuel" is that the last few days I've often smelled a definite petrol odour while driving with the window down. Nothing much with it up, and not a great stench in the trunk either in general. Can't really smell anything petroleum-y under the bonnet either. It's not really an issue at idle, but is definite while driving at normal town speeds/revs (up to 2000), and when I floor it and hit 3,000 rpm, it's very noticeable.
This site suggests a link between the FF44 and the fuel vapour purge cannister:
https://www.maxperience.com/en/question/engine-check

I rang the garage who were supposed to have fixed it, and will take it around on Wednesday to say "Oi mate!". But any extra guidance I can give them would be appreciated....

(From a list I found
Possible faults:
Fuel pressure fault,
Stuck open purge valve,
Poor ground connections,
Poor oxy sensor ground connection,
Open or short in oxy sensor heater and/or output circuit,
Defective air injection pump or circuit,
Intake air leak,
Plugged fuel injector (or bad electrical connection)
Defective maf sensor.

 

Could definitely be the vapour recovery system.

From your list, the V12 does not have a MAF sensor. It uses the vacuum level to calculate the airflow into the engine, rather than measuring it directly.
Certainly the petrol smell is a clue, as that isn't normal. Interesting that the smell increases with revs. Maybe the fan is blowing it back? The 6.0's have a second fuel pump that comes on above about 3200 rpm, but the 5.3 only has a single fuel pump.

 

Thanks again, Jagboi.
No MAF? Well, that's one less thing to break, I guess.... This applies to the facelifts/Marellis as well? But vacuum level being used could suggest a vacuum leak somewhere. Vacuum measured from where--the intake manifold?

I assumed that the increase in stink with the increase in revs is due to more fuel being poured through the system in general. If there's a leak in the vapour recovery system, then the more revs, the more fuel, the more vapours pushed into the charcoal cannister and then leaking from somewhere. I wouldn't be surprised (okay, I would be pleasantly surprised) if this is connected with the Whoosh when opening the fuel cap most of the time--a blow whoosh, not a suck whoosh.

I did the smell test just now, with the engine nice and warm. A definite odour of fuel from the left-hand pipe. I could smell it merely by bending down. Perhaps that's the cause of the smell--though not sure how it would get from there back to where I could smell it in the cabin. Presumably that's not the only place it escapes, thought at idle with the bonnet open, I couldn't detect any strange smells. I would have imagined the right-hand pipe would smell, as FF44 is a right-hand warning, but clearly something is going on that shouldn't be going on....

 

All V12 with injection used the MAP (Manifold Air Pressure) system, as opposed to MAF (Mass Air Flow). The vacuum take off is in the middle of the crossover pipe at the back of the engine, which joins the two intake manifolds together, and it runs the length of the car to the ECU in the boot.

The way the system works is the fuel pump runs continuously, and pumps fuel to the engine. The first pressure regulator drops the system pressure to 45psi, the fuel enters the fuel rail and to the injectors, and the last pressure regulator opens at 38 PSI, so the rail pressure should be a constant 38 PSI, with reference to the manifold pressure. That's why there is a vacuum line to the pressure regulators, so the difference between the manifold pressure and fuel pressure is always 38 psi. Any fuel that isn't injected into the engine is returned to the tank. Thus the pump always supplies more than the engine can consume at full power, the excess is returned to the tank and the fuel is always circulating. That's part of the reason there is a fuel cooler in the AC system, and the AC will run even if it is turned off, to cool the fuel. It does pick up quite a bit of heat flowing through the fuel rail and over the engine.

I'll have to reread the vapour recovery section, but I think there should be slight vacuum on the tank, not pressure. I'm not 100% sure about that.

You can smell raw fuel at the left exhaust pipe? That would generally indicate ignition problems, like a bad plug or plug wire causing a misfire. Possible it's an injector, but not as likely. It's easy to detect if they are all firing, take a long handled screwdriver ( or something similarly solid) and put one end on the injector body and the other on your ear with the car idling. You should be able to clearly hear the injectors clicking as they open and close. If one isn't working, then you have a culprit. The exhaust does not cross over between banks, so one side won't affect the other.

 

This is the evap page from the 6.0 manual, I think the 5.3 should be very similar.

 

Thanks very much for that very detailed account. (Though there's no fuel cooler in the facelift a/c system). I'll have a look at the back of the manifold cross pipe and see if the vacuum takeoff looks fine.
I believe there is vacuum on the tank, yes, from what I've managed to find, but the vapours are drawn off somewhere (into the fuel system, I read), so a leak there could allow the smell to escape. At any rate, reading up on the system in general, this appears to be a Thing That Can Happen.

I checked the injectors right after checking the exhaust smell, using a long-shaft screwdriver bought specially for that purpose last year. All clicking away happily like clockwork. No obvious leaks either.
The ignition system is basically new, but that doesn't mean there can't be a duff bit somewhere. Being a Marelli, there's two coils in the vee.
Front coil: replaced 2016 (brand unknown: hope it's not URO)
Rear coil: replaced last week
Ignition wires: replaced 2017
Spark plugs: replaced 2016
Rotor cap: replaced Dec. 2017
Distributor arm: replaced Dec. 2017

 

The garage just phoned. They measured the O2 sensors and found that the LEFT (port) one was reading low voltages. The guy said this can happen when one's replaced and the other isn't and there's an unbalance of power or something. I'm suspicious (why not an FF45 error then?), but it does fit the symptoms to an extent--initially fine after the starboard replacement, then increasingly worse as the unequal load became more and more.
Maybe. I'm very sceptical, but we'll see. I don't really know enough to say that it couldn't be the issue.

 

That does seem odd. As you say, why no FF45? I have never heard of one side affecting the other like that; as I think about it I can't see how it is possible. Do you know what brand of sensor they used?

Just for personal amusement, could you give each wire a push at the plug end to make sure it's seated on the plug? Another thing to check, although a bit more difficult, is the spark plugs have a threaded post on top, and then there is a topper that has the hourglass shaped profile to engage the plug wire end. Sometimes this threaded topper works loose and it can give intermittent symptoms of a misfire. Pull each spark plug wire one at a time and give the plug end a twist and see if any are loose.

Unfortunately you have the GM A6 AC compressor, so that means the front 4 plugs are basically inaccessible without unbolting the compressor and setting it aside. You should be able to access the rear 8 though. Then at the distributor cap give each end a push and a little twist to make sure the wire is nicely seated. Some caps have aluminium terminals and there can be a bit of corrosion in there, giving the wire a twist can clean it up.