Oil cooler hoses! A must while you're under there. Easy with underparts removed and inexpensive to have a hydraulic shop replace the hoses and recrimp original hard lines. Hi temp, hi pressure oil resistant hose ONLY! I used Parker Push-Lok 836, blue, 300 PSI 150 deg C.

I believe Oliver is undertaking these tasks right now too.

 

Good suggestion Sleek. Just to add to that, I used Aeroquip FC598-12 hose. Looks more factory than the blue hose I think and it seems to have the same ratings? Can get it from HoseWareHouse online.

 

The shop has not mentioned the oil cooler hoses needing service. It's possible the previous owner had them changed; I'm pretty sure he had at least one of the PS hoses done.

 

The front-subframe-out service is complete. The problem where half the engine cuts out recurred just before the invoice was to be drawn up. On the bright side, this means the problem will get diagnosed and fixed. Too bad it will now take even longer before I can bring the XJ12 home.

 

Just brought it home after 7 months and a lot of dollars. The B bank cutting out was determined to be due to a dying, corroding ECU from water intrusion. A used one was sourced and fitted. That also should take care of the intermittent trans fail light.

My list of problems/to-do is now at 57 items complete and 30 pending or in progress, most of which are cosmetic or mere annoyances.

 

Time to enjoy your ride! Get ready as you will be noticed and compliments will surely follow.

 

The car drives pretty well now, but new problems have shown up.

Long crank time when cold. Probably needs a battery, since it likely wasn't maintained during its long stay on the healing bench.
Alternator was intermittent the day after I got it back. Seems like that may have fixed itself.
Sunroof wasn't tilting very far, so I pushed up on it and in so doing, broke the RH tilt/slide mech. 😫
Clock display is intermittently faded to illegibility.
Exterior temp display intermittently "--"
NOT CONT pretty much always, but the A2D-JAG97 bluetooth module still plays, until it doesn't. I noticed the HU was blazing hot last time that happened.
Two additional occurrences of TRANS FAIL lamp popping up. Grumblecakes.

 

It got a lot worse yesterday. I was going to get the spare replaced and order tires for the Solars, and along the way pick up a new battery, but the car would not start. After three hours on the maintainer, I reprioritized the battery. Driving home with the new battery (not yet installed), the trans fail light was on the whole time and the shifts felt hard. After putting the new battery in, the climate control started beeping with codes 12, 23, and 41. I still had time to get a new spare and request some 17s, so I drove anyway. I was hearing new mechanical sounds at engine speed, like a Ford power steering pump. I got two blocks away and started feeling very pronounced hesitation, so I returned home and limped the car back into the garage.

Codes are P0108, P1775, and P1780. Trans fluid looks the same as last time, over full hot and some bubbles. I have the (new) battery disconnected now to hopefully right things with a hard reset, but it seems like the trans may need a rebuild.

 

I would try a rebuilt valve body with the upgrades already done first. Got mine for 250 off ebay . Also change out the speed sensors if you haven't already. This can be done with the exhaust in place but its a bit of a pain. I had hard shifts with an occasional P1775 and solved it by doing this and also backing off the EPC(biggest solenoid) set screw half a turn which brings down the main line pressure and gives a softer shift. Car is happy now.

 

G'day Gents,

I had an ongoing problem with my tranny which eventuated in a complete rebuild. The basic problem was wear in the AFL (Actuator Feed Limiter) valve, it is a hardened steel shuttle valve in the soft alloy valve body and it's axis is horizontal and over time wears the bore in the valve body out of round and then the problems start.

I found the following article which explains things much more clearly than I can.

AFL Valve.

1993 to 2018 General Motors vehicles equipped with 4L60E, 4L65E, 4L70E, 4L75E and 4L80E automatic transmissions often wear out the actuator feed limit (AFL) valve bore. As a result, inadequate pressure rise and shift solenoid feed oil loss can occur. This can cause trouble codes, wrong gear starts, falls out of gear and clutch plate burn-up.

The purpose of the actuator feed limit valve is to limit the pressure going to the actuators (aka shift solenoids). The AFL valve spring is calibrated to prevent the pressure from ever exceeding a predetermined pressure, no matter what the main line pressure is. This is necessary to prevent more fluid from being fed to the solenoids than they can physically exhaust and to limit the maximum line pressure output.

On one hand, if the pressure feed to the ON/OFF shift solenoids is higher or lower than intended, the shift valves controlled by those solenoids may not do what they should. For example, too much pressure could flood the shift solenoids, making them act as mechanically stuck closed solenoids. Alternatively, not enough pressure could make them act as mechanically stuck open solenoids. As a result, the transmission can have wrong gear starts, or fall out of gear.

On the other hand, for pulse width modulated (PWM) solenoids like the line pressure control solenoid (PCS), if the feed pressure is too high or too low, the consequences can be detrimental. The PCS output controls the line pressure based on the calculated load from the computer. Consequently, if the AFL pressure feeding the PCS solenoid is too high or too low, the line pressure output will also be too high or too low. As a result, the transmission will either slip and burn frictions, or have hash shifts.



PWM/TCC Valve

1991 to 2013 newer General Motors vehicles equipped with 4L80E and 4L85E automatic transmissions often wear out the torque converter clutch (TCC) regulator valve bore in the valve body.

The TCC regulator valve function is to regulate the torque converter clutch apply pressure. The computer varies the pulse width modulation of the TCC PWM solenoid, which regulates the apply pressure of the lock-up clutch. Because of the constant PWM solenoid induced oscillation, over time, excessive wear of the bore occurs. As a result, the computer loses the ability to control the lock-up clutch apply rate and slip rate properly due to the loss of TCC apply pressure.

 

Jeff, just as a point of reference, what was the approximate age/mileage/kms on the trans when yours was acting up?

 

The core of these 4L80Es is fairly robust from what I've read. Its the valve body that causes issues well before. I would hesitate to rebuild the transmission unless you have been running it with issues for many thousands of miles.

 

G'day John,

The initial problem started years ago at around 180,000 miles and what happened was that on the first start and drive off of the day the tranny light would illuminate and computer control of the tranny would cease and it would run fine in the normal mechanical mode. No limp mode ever. If I then stopped and restarted the engine the problem would clear and not recur for the rest of the day.

Fast forward to recently, at around 225,000 miles, the problem recurred and would not clear so I took the car to a tranny workshop and when I described the fault the tech instantly said "Ah it's your AFL valve" and then he described a whole lot of other symptoms which my auto was suffering. As you can see from the article above a faulty AFL valve affects all sorts of things in the tranny.

It is behaving perfectly now.

He also said that if I'd had things attended to when the original problem occurred then I wouldn't have needed a full rebuild but just a repair of the AFL valve, and there are repair kits available.

Cheers,
Jeff.

 

Thanks Jeff. Can't believe you have 225K miles on your Jag V12!! I hope mine makes it that far. Id say getting that many miles out of one of these transmissions before full rebuild isn't doing bad at all.
I looked into doing the AFL valve upgrade. I really wasn't comfortable with boring out the valve guide with my equipment and just got a rebuilt valve body with the upgrades. We are lucky this transmission is common in the US and you can get really good prices on rebuilt valve bodies. I suspect the same in Australia? One more change I had to do was reduce the line main line pressure on the EPC solenoid. Just a half turn and my shifts with a noticeable bump, are now so soft I cannot feel the shift at all. I hope I didn't go too far and am burning up the clutches.

 

Today I lubed the door hinges, checks, and strikers and applied Gummi Pflege to the weatherstrips. Then I finally took on the business of the engine cover's chipping paint. Before:

After most of a 40' roll of Scotchcal 70205 1/8" striping tape, which looks like this:

I got it to look like this:

The stripe tape was way easier than I could possibly imagine painting would be.



The XJ12 goes back into the shop on the 1st.

 

As Parker says, "Cue the saxaphone music"!

How many hours did that take?

No matter, it was worth it. "Perfect Enough" is my motto too.

 

About 4 hours in total, one of which was taken in the remove/replace and washing of the cover. We'll see how long it lasts.

 

I was planning to drive the XJ12 to its appointment, but it was a crank-no-start this morning. I would've spent more effort trying to troubleshoot it, but it might have been another month to wait for a slot at the shop so I got it towed in.

 

After 3 more months at the Shop, I got the car back yesterday. I've only driven it the few miles home, but the shifts are still firmer than they should be and the TRANS FAIL light is on steady. Shop says they pulled a code for a shift solenoid.

It's apparently popping fuse 11 in the right front fusebox, which AFAICT provides power to the injectors, so they put in a self-resetting circuit breaker. Guess I'll have to find the fault.

 

I drove the car around town all day Saturday. For the first five minutes, the trans light was off and shifts were smooth. The rest of the day, the trans light stayed on and shifts were hard, which leads me to believe that the transmission itself is probably fine, it just doesn't get full command from the TCU. I'm kinda suspecting the notoriously too-short trans wiring harness, if not TCU moisture ingress similar to my ECU.

Also noticed an ugly sound coming from the left side (though TBH I couldn't hear it at all until rolling down the window). Sounded like, and was, a rattling dust shield, which Jaguar apparently calls a Disc Shield.
There are Torx bolts behind the hub, but I couldn't get the cap off to get to the hub nut to be able to remove the hub. I managed to stick a 4mm allen key through the screw hole in the hub face to slightly tighten the lower bolt, but the upper one stripped before I could get it to fully seat. The hub really should come off at least to clean up the filings stuck to the ABS sensor, and the bearings feel really tight to me, so it's going into the shop in a couple weeks when they have a slot.