Try changing the fuel filter. (Apols if you've already mentioned that you've done that.) Many of the symptoms you describe relate to a partially blocked filter or an intermittent fuel pump operation. It needs a new filter anyway, so a cheap maintenance job.

Good luck

Paul

 

I'm entirely uninformed on the topic, so I'll look into it. I am concerned about the full tank of 6-week old gas, and was already contemplating adding a stabilizer.

Thanks, Paul. The filter has long occupied a high position on my theoretical suspects list. I'll look for it this afternoon. Behind a panel in the back of the RH wheel well, jah?

****UPDATE: LH wheel well, duh.

I've read so many threads about folks getting confused and into arguments over this location, I've confused myself. That MY93 update pdf with the wrong location is a real pain. I think I've found the panel where expected; looks like just two Phillips screws that I can see. I need to tool up a bit in order to take the front wheel off.

 

If your filter is behind the panel in the back corner of the LHF wheel well, then I think there are more than 2 fixings. 4 or maybe 6 rings a bell?

When you change it, remember to pull fuel relay in boot then turn starter to discharge pressure. Crack the top and bottom unions (can be very tight) BEFORE undoing the mount bracket.

Good luck

Paul

 

I had a similar problem with my 93 xjs conv. It took me 6 weeks to find out that even though I had spark, the coil wasn't putting out a strong enough spark. Changed the coil and coil wire and no more problem......yup...I was getting an FF44 code and am still considering changing out the O2 sensor.

 

Did replacing the coil resolve the FF44? I'm still gearing up to work on the fuel filter, but the nice thing about having a running AJ6, is I can test the coil very easily. I don't think I'd take me more than a few minutes to swap out a known good coil, so I may try that as soon as the weather and time permits.

 

Hi,,,,,,,It appears that changing out the coil and coil wire has cleared the FF44 in my Jag. Don't ask me why, I still can't understand how I even had the problem. The spark seemed really good to me. When i finally brought a real mechanic to my garage he thought it seemed a bit weaker than it should have and I guess he was right.
I keep looking for the FF44 to come back but knock on Jaguar Burl, it hasn't.

 

Your Jag was built about 500 cars before mine, based on the VIN. Known problem and TSB from that group: insufficient engine block grounding leading to intermittent FF44.
Problem: engine looks for ways to ground itself, often through the O2 sensor, burning out wires. Solution: Install a heavy copper wire from the ground connector on the firewall to any convenient engine head bolt. After I did this I then opened the wiring harness and tracked down the burnt/melted wires and repaired them.

 

The coil tests out good. I just swapped the coils between my two cars. Unfortunately, I foolishly broke the positive terminal on Coil A (known good coil) while installing it in Jag B by over-tightening it.

Will not do that again.

However, I successfully installed Coil B in Jag A to complete the swap test, and the car runs fine. (Thank goodness; I need this car running.)

In your case, I'm guessing that if your old coil was causing incomplete burn, the O2 sensor would pick that up as an over-rich signal. That would actually be an example of the FF44 test circuit performing as designed, instead of a false negative sensor failure.

That is great info. Thanks very much!

I will try to track down that bulletin. Roughly what gauge are we talking about for "heavy copper wire"?

More fuel for the fire:

It's raining this morning. It's been raining for days, and isn't about to stop (I think this weekend will finally get us above multi-year drought conditions). I had to work on the car during lulls in the rain because I can't wait for the weather anymore.

The car will not start for anything this morning (I mean before pulling the coil). Nada. Zilch. It sure seems like there is a moisture-factor somewhere in this mix of problems.

 

Ticket #5: Replace Ignition Coil

I damaged a working ignition coil that needs to be replaced. Replacement Bosch unit now on order from Rock Auto.

TSB 18-57: MIL Illuminated – HO2S – DTC 44 and/or 45 – Add Ground Straps – Service Action S494

This bulletin specifies the addition of supplementary ground straps on V12s in the VIN range of 188105 - 221234. My car is a 4.0 liter AJ6 previous to this VIN range, but anything is possible, and the same principles apply, so I will look into adding a similar ground strap as a precaution.

 

Hahaha, it's always something brain-dead simple like this with the AJ6.

I finally managed to get the replacement coil installed on Monday, but more incoming rain prevented me from testing it further until today. So this afternoon I've got everything hooked up and the induction light is ready for validation testing, but I don't like the way the coil wire (for spark) is not giving me a solid click. It's also failing the induction light test. So I swapped out the wire from Jag A. Boom, car fires right up.

Not only does the car start, but the engine is running smooth. I've let it come up to temp, I've revved it pretty solid, and I even gently drove it around the block for the first time. No stutter, no missing, no fuss.

Huh. Well, that wire was on the short list for the next replacements, anyway. I'm not sure, but that might have been the source of the FF44 code as well, if it was causing a rich reading at the O2 sensor. I'm not sure that one wire explains everything that happened with the engine, but it's looking pretty good for the moment.

Will a code like FF44 clear itself after driving the fixed car above a certain speed, or do I need to reset the ECU manually?

I am now immediately faced with a couple more urgent issues to solve. I've got an e-brake light on and there is a legacy issue with the gas tank rearing it's ugly head.

Ticket #6: Brake Light Stays On

So, I've read this thread before, heh. I'm pretty sure I am releasing the brake correctly: lift the loose lever until the resistance starts near the top, then depress the button, lift the remaining short throw, and then lower with the button pressed in all the way down. I can alternate this with a straight pull (brake on/off), and everything feels and sounds as I'd expect. However, the idiot light remains on.

I will definitely look at the switch, and there is a lot written about that topic here on the forum, but let me add a couple of points. The convertible top has a very large rent in it, the car sat up at a shop lot for a long time in unexpectedly wet weather, the cover I put on it was simply inadequate for keeping all the water out, and some damage has occurred in the interior as a result. This could definitely support the idea of the brake switch suffering from moisture.

I also noticed right away a mild scraping noise from the car once it got it moving. This could be the handbrake not being 100% free, providing some slight friction. There was no noticeable drag on car movement. If there is, it is very slight. However, I've also experienced this very sensation with rusty disc brakes after a long sit, and in the past this has resolved itself after getting the car out on the road and exercising the brakes.

Any suggestions on how to best proceed with this?

Ticket #7: Severe Gas Fumes

I got about halfway around the block (with the top down, btw) before I was assaulted by the raw gas fumes coming from the back. Now, my first '93 convertible had the same problem, and the issue in that case was the vapor recovery system was not hooked up properly and venting to the trunk. I was told at the time that this wasn't particularly dangerous.

However, this car has had a trunk fire from gas getting onto the carpets, which adds a whole 'nother dimension of "oh ****, do I smell gas?"

I'm not sure retelling the whole trunk fire story I pieced together from the previous owner is worth the bandwidth. I will say that I only experienced mild fumes when I attempted to drive the car home this winter (when gassing up on the highway). However, I don't like the look of the gas filler internals, and will feel better if I have all the connections to the tank checked out.

Ticket #8: Replace Balance of Ignition

Now that the engine starts, I'm ready to order new plugs, wires, cap and rotor. I think in the future, I am going to prepare a nicely packaged kit containing spares of all of the above to reside in the trunk at all times. My AJ6's have been rough on the serviceable ignition components.

Champion Copper Plus RC9YC (Part #344) with an 0.032 gap, right?

 

I also have a 93 xjs 4L convertible. I've had my share of intermittent issues where I find my car just won't start. I finally made two changes that help me...

First, I found a fuel pressure gauge and a brass in-line connector for the gauge. I carefully cut the fuel line in the engine bay where the high-pressure fuel is sent to the fuel rails, and I installed the brass connector for the pressure gauge. I used FOUR FUEL INJECTOR clamps to secure the connector... after all,
I don't want to be the cause of an engine fire.

Now, if/when I have a problem, I can open the hood, and screw my fuel pressure gauge to the port that is permanently installed. When I turn the ignition key, the fuel pump should kick on, and I can read the fuel pressure both in that state and when I crank the engine.

Second: I bought a spark-tester. It connects to one of the spark plugs and the plug boot connects to the other end. It has a visible gap that is adjustable. The idea is that I can visually see if I'm getting a good spark when I'm cranking the engine.

Third (actually... this one is a TO-DO), I read on-line about using a simple test light to ground one end, and connect the other end to one of the fuel injector wires. When you crank the engine, the light should flash to indicate that the injectors are getting a pulse. I think I'll have to add that to my road-side diagnostic kit.

The bottom line is that once I put together this little kit, my jag hasn't stranded me since, so I haven't had to use it. But it's a good feeling to know that if the car won't start, I have a few simple things I can do where ever I am to at least do some preliminary analysis.


BTW... I've had my fuel pump replaced by a shop, and they did the fuel filter and relays for the fuel pump too.

Also, at my last inspection my car had a rough idle. It turned out to be the engine ground problem. The shop added a grounding strap to the engine block, and it cleared the problem up immediately. So... yes... the AJ6 engine also suffers from poor grounding, and as was stated that can cause the ground to go through any of the wires or cables that connect to the engine and wear them out. This could include the throttle cable and the wires for the Tach, among others.

-----

Some other comments... I also had a factory alarm. My jag must has some type of parasitic power draw, so the battery will die if it sits for a month of more without running. This causes me to have to jump the car, and then do the five-presses on the remote to program it to the factory alarm.

The problem was always that when this occurred I only had my remote for the alarm and not my wife's, so her remote regularly would not work. (you can program up to five remotes to the factory alarm. Each press is learning one of the remotes).

My solution was this:

1) I removed the factory alarm entirely and replaced it with an inexpensive, alarm made by Directed Electronics Inc (like the Avital Model 4103, or Python Python 5103P) model that supports a remote start and remote trunk release. It controls the door locks, and I eventually hooked up the remote start and added a solenoid to the trunk to even enable the remote trunk release. The particular model I bought has a "vacation mode" where it monitors the battery voltage, and when it drops below a certain level, will start the car and run it for a pre-set amount of time to charge the battery. It exits vacation mode when you drive the car, or after 1 month. The range on the factory alarm was lousy (sometimes it didn't even reach when I was standing in front of the car... I would then have to walk to the back of the car to get it to work... and yes... i changed the remote batteries, and I also checked and tried to position the long wire in the trunk that serves as the receiver antenna for the factory alarm).

2) Although I liked the idea of vacation mode, the reality was I didn't remember the key sequence on the remote to engage it. I ended up adding a quick disconnect to the ground cable at the battery. Now, if the car will sit for a while, I open the trunk, and turn the disconnect screw about 3/4 of a turn, and the battery is disconnected. When I come back, to the car, I just reconnect the battery, and I'm good to go (except for radio stations and the clock!).
This works well -- in part -- because I removed the factory alarm, and unlike the factory system, the aftermarket alarm remembers the remotes, even when the power is cut.

3) The factory alarm has it's own back-up battery to retain the settings. When I removed the factory alarm (I took the whole thing out!), the alarm was in a black plastic or metal case that had two parts. When I opened them up, one part had the electronics for the alarm, and the other part had a rechargeable battery along with a diode that allowed the car to charge this battery, but prevented the battery from discharging back into the car's electrical system.

If you keep the factory alarm, you may want to replace that battery. If you can't find the original, find or make a setup out of NiCad batteries that is the same voltage as the factory back up and wire it in. I found it easier and cheaper to buy an after market alarm online.



Good luck. I look forward to following your thread.

 

Here's a tip when replacing the battery...

Get a quality AGM battery. Because the don't put out gas when they charge, you don't have to worry about venting the gas out of the trunk. The factory battery and proper ones that are compatible have a small port that connects to a hose that lets the gas vent so it won't be trapped in the trunk.

I personally got one of the $300 Odyssey batteries. They're expensive, but they last a long time, and when disconnected, they can sit for up to two years and still have 80% charge left. So when I put my jag away for the winter, I disconnect the battery, and when I go to fire it up in the spring, my battery is still good. No need to remove it for storage or to charge it.

 

I want to thank you taking the time to write your comprehensive post. It was very encouraging! Unfortunately, I had other distractions at the time. The crazy weather here finally culminated with flooding just over a week ago, so I was just a bit preoccupied with other concerns.

However, the carpets in my house are dry again, and with the new dehumidifier, carpet cleaner, pool pump, and $1,500 later, everything is back to normal. Hah!



Now that summer has simply materialized in full force as if nothing happened, I can focus on the Jag again. I drove it a bit tonight. I replaced the plugs, plug wires, cap, and rotor. Starts and runs great. I need to clear the FF44 code, and see if it comes back, but so far, so good.

I exercised the handbrake some more, and that cleared the idiot light. I'm pretty sure the scraping sound is just rust on the rotors.

Tickets #6 & #8 are now closed.

That leaves the gas smell. The primary suspect at the moment is the fuel filler, which I've taken out for examination. I may post about that more in a new thread.

 

I'm neck deep in das boot trying to sort out the fallout from the PO's carpet fire.

I isolated the fuel vapor problem to the open fuel overflow pipe and vapor recovery system. I have a jury-rigged solution in place until I can properly install the fuel filler according to spec. Ticket #7 is now pending final fuel filler re-installation with bells and whistles.

I have now moved on to the fried electrics, which is probably the single biggest issue facing this car. It's amazing how much of the wiring still functions despite the serious scorching the LH trim panel suffered. For example, the ABS ECU, module, and associated wiring were barely soot-stained, and I suspect the ABS system is fine. While the main LH harness took some insulation melting and a length of about six or eight inches is fused into a hardened block, the wiring inside it remains continuous. The fuel gauge works great despite the slosh module looking like this:



The two pressing failure states are no brake lights (none, zip) and no turn signals (no flasher, hazards, nada). The speedo is also kaput, but Texas safety inspection won't fail me for that.

Ticket #9: Restore Brake Lights

The main running lights, headlights, reverse lights, and side markers all work normally. However, none of the brake lights are coming on. The bulbs are all good (swapped out with the other Jag) and new ones are currently installed. There is a bulb out warning on the dash. The tail lights, brake lights, and turn signals on each side all share the same grounds, so those are good.

The stop lamp bulb failure unit is baked out and rattles when you shake it. I've attempted to order a used unit from Motorcars Ltd, so we'll see if that ships. These appear to be completely long gone NOS. The brake relay looks okay, I'll still need to swap test that with my other car. The actual brake switches work fine (I've had to exercise the e-brake a bit to good effect).

This problem is down the the failure unit, the relay, and attendant wiring.

Ticket #10: Restore Turn Signals

No clicky, no flashy! On either side, front or back. The left side I can understand, but not the right side. The flasher is good (swapped from Jag A) as is the hazard switch (ditto). The left signal circuit wiring is GR (green/red), the right is GW (green/white), and I have found a GW wire in the LH harness meltdown, but it appears to lead to a dead-end connection. The grounds are shared with the tail lights, so those are good.

This has got to come down to open GR/GW circuits. The turn signals are super-dead-simple downstream of the turn signal switch and should work independently of each other and the front bulbs as well (missing front bulbs only cause faster flashing). Still trying to understand this one.

Figure 6 of the '93 Electrical Guide and I have become close friends.

Ticket #11: Restore Speedometer

The speed interface is looking pretty slagged and most of the insulation from the induction sensor in the diff is gone. I haven't performed any surgery yet, but it looks like these cables are coax with (I guess) two shielded wires inside? This ticket is on hold until I get the paperwork on this car finally resolved.

 

Hi Kurt,

I'd love to hear an update on your progress.

ONE)
I've got issues with my parking brake light too. In my case, I know that a
shop over-tightened the hand brake adjustments when they did a brake job, and then I suspect that they over-loosened them when I brought it back.
I just haven't had time to look into that one.

TWO)
My Speedometer is also intermittent. It doesn't pop in and out rapidly. Rather, it will work fine... like for months at a time... Then all of a sudden it won't work... possibly for months at a time. Repeat as often as the jag feels like it!
I have no idea where to start, other than looking for the "input signal" to whatever computer receives an input. I recently spent $65 for a multi-meter on amazon that includes a rudimentary oscilloscope function.

I think it's chinese designed and manufactured. The brand is "Liumi" and it's described as "Oscilloscope Multimeter, LIUMY Professional Handheld LED Scopemeter Oscilloscope Multimeter with 200ksps A/D Automatic Waveform Capture Function, DC/AC Voltage /Current, Resistance Test with Backlight")

The Oscilloscope, isn't great, but it DOES work, and it will probably meet my need for something like tapping into a speedometer input to check for a signal and see how it varies with time. Of course, right now, I don't have enough info on what wire, where, or what the signal should look like. All that I can tell, is that when I turn the car to the "on" position, the speedometer moves from all the way down to a reading of Zero MPH, so at least that part is working. All other gauges seem fine. If I need a better oscilloscope, I'll buy one of the slighter better (but still far from professional) scopes that are basically 3" or 4" tablets built and designed to operate as dedicated oscilloscopes. Amazon has some for about $120 to about $150, for some that have more features than my multi-meter with scope, and they are still cheap -- although they all seem to use rechargeable batteries that are probably non-standard, so I worry that I might only get 2 to 5 years out of the scope before the battery becomes unusable, and at that point I may find that my scope is unusable -- that's the biggest unknown that has kept me from buying one so far... the multimeter I bought takes 4 aaa batteries, so as long as it doesn't break, I should be able to use this tool for 10, 20 or more years -- and that's how I like to roll... buy it once, and then have it for as long as I need it.

THREE)
I also have the FF44 error, and my car *is* running rich, and failed emissions inspection. I think that in my case, the main computer (ECU,,, ECM, something like that) really isn't getting a correct reading. I've got lots of info on diagnosing the issue by reading the value from the black O2 sensor. I've already replaced my O2 sensor with a Bosch model 13032 Oxygen Sensor. It's plug-in compatible. I've learned that the two white wires are for a heater circuit. One of them gets grounded, and the other gets +12V. The black wire is the signal wire, and it should oscillate from about +0.3V to +0.9V which signals rich and lean conditions (I forgot which is which). Our cars have O2 sensors that only read out rich or lean, so our computer is set up to add fuel when it gets a lean reading, and cut fuel when it gets a rich reading... this the normal steady state is that the reading will oscillate back and forth between these two values. In my case, when I replaced the O2 sensor, I discovered that the factory wiring harness was burnt. I replaced those wires with marine-grade wires, using crimp on "butt" connectors with heat shrink ends to waterproof the connections, then covered them with heat shrink with adhesive, and finally with 3/8 wire looming. You DON'T WANT TO SOLDER, because it gets too hot under the hood, so solder could melt.

I've still got to trouble shoot my problem... because I still get a FF44 error. I've since read that until the car warms up, it basically ignores the O2 sensor, then once it's warmed up which can take 2 to 5 minutes of idling (approx), it changes to "closed loop" mode where it tries to use the output of the 02 sensor.
On my car, I can tell when this kicks in, because the engine runs very poorly, sometimes racing, and sometimes stalling or almost stalling, then after struggling to get it right, the FF44 code comes on, and the car starts to idle better but too fast (about 1000 RPM or faster). What has happened is that the FF44 code means that the computer has found problems in the 02 sensor feedback, and is now ignoring it and running according to a pre-programed map that ensures that the mixture is a little rich.

It will stay in that mode until I clear the FF44 code. I do that by disconnecting the negative battery terminal (which I have permanently run through a marine "battery disconnect" switch mounted in the trunk, so it's easy. There's info on a wire somewhere under the shift console that you can touch to ground for a short moment to clear an error code. The advantage of that method includes that if there is more than one code, you onboard computer will then display the next stored code. I plan to wire up a momentary push button switch (probably inside the center console) so that I can easily clear codes that way.

Regarding the FF44... in my case I believe that the computer isn't reading a proper signal from the 02 sensor.... and that's consistent with my observation of the wiring harness being fried (shorting all of the wires together).
I've read their is an IN LINE fuse for the heating circuit on the O2 sensor.
I've also seen mention on the 1993 MY of there being a separate RELAY that provides +12V to one of the heater wires for the 02 sensor, but unfortunately, I can't find any reference to that relay on the wiring diagrams for the MY93 that I have examine. On the MY92, this heater to the 02 sensor was reportedly powered by the fuel pump relay.

So, I'm going to try to find a place to get a reading to see if +12V is being applied to either of the white wires on my Bosch 02 sensor. If the answer is no, I'm leaning towards cutting those two wires in the harness, and sealing them up, and then running my own, NEW wires to the heater circuit on the 02 sensor... grounding one of the ends in the engine compartment, and tapping into a +12V feed that is ignition switched for the other white wire on the heater circuit. I've already purchased a 20 amp in-line fuse to wire up, and I'll need to tap into a feed that can handle the extra current load, which should be under 3 amps (based on 5 ohm load and under 15 Volts -- using ohm's law). So something like the output to the fuel pump relay could be a good candidate.

Anyway, just to test, I don't even need a switched feed... I could even run a wire straight to the battery... outside the car (with a fuse of course) just to see if my theory works. If and once I've proven it will work, then I can find a better tap inside the engine back (or inside the passenger cabin) and figure out where and how to tap in... Actually, now that I've typed it... I like that idea. If I were to run my new wire into the passenger cabin, I could tap into a power feed on the back on the one of the fuse boxes, and put in my own in-line fuse.
Maybe even using something like one of the (unused) 2 circuits related to a radio telephone.

If the circuit I choose isn't ignition switched, I could always add a relay (with a proper resistor or diode to prevent voltage spikes when the relay turns of) to change the feed to be ignition switched.

The last concern (to me) is whether cutting the wiring harness to disconnect the power feed to the heater circuit of the 02 sensor will cause the car to throw a code -- meaning, does the car check for a load on the heater wires, and throw a code if one isn't found. I figure that by testing, I'll find out, and if it turns out that this DOES cause a code, then I will examine the wiring diagrams, and look for a place near the proper computer to find the wire or wires that cause the code, and splice in a correctly sized resistor either between that wire and ground, or between the correct two wires if necessary, to trick the computer into thinking that it is powering the 02 heater. Of course, this may not be necessary, because the diagrams I've read don't seem to indicate that the heater part of the circuit is directly monitored. Only the output reading from the 02 sensor is checked, and a code is thrown if the value doesn't oscillate from rich to lean as expected when run in closed loop.

One last note. It turns out that the 02 sensor get's it's "fresh air" from air that enters through the wires themselves and their connections. So if you get grease on your O2 sensor wires, you can block up that path, causing the sensor not to get fresh outside air as a reference point, which can cause the 02 sensor to give bad readings, and trip a FF44 code. In fact, that's why the O2 sensor has some type of soft heat shield around the wires at the point where the 02 sensor screws into the exhaust. I saw a TSB where jaguar was adding this soft heat shield to cars without it, and they stated it was to keep dirt and moisture off of the 02 sensor wires, so that they don't get wet and dirty which can cause bad readings from the sensor.

Anyway, I write all of this not to hi-jack your thread, but rather to share my thoughts and what (i hope) is helpful information. I plan to start my own thread about my FF44 issue, since my cause may be different from yours.

Nonetheless, I believe that all three of the topics that I just posted about are on-point regarding "open tickets" in your post... so I hope they help.

PLEASE GIVE US AN UPDATE ON YOUR PROGRESS!!! :-)

Cheers!

-Phil

 

The original post in this thread reminded me of taking the Duchess from Tennessee to Mackinac. (Stayed on the island for a week) It was a good trip with many long straight sections on I-75 where you could really open her up.
There was one really long straight section where I took her up to 155 mph or so, before I got cold feet about some Smokey sitting just beyond the next hill with a radar unit. She certainly felt like she had a lot more left and the speedometer
goes all the way to 170, but what looks like a flat road, really isn't so flat and level at that speed. I had absolutely no hint of anything amiss during the entire trip, my wife loved the comfortable seating and little road noise.