84 XJS HE With the V12. Initial complaint was a no start after sitting in storage over winter. The ECU wasn’t grounding the fuel pump relay so I tested the power and grounds to the ECU and all tested good so I opened up the computer and found a cracked solder joint on the connector ground pin where it connects to the circuit board. Resoldered all the connector joint and fixed that issue.

Now I’m getting inconsistent results so I don’t know if I have multiple problems or one thing causing everything. Sometimes it takes forever cranking to get it to fire. When it does fire I get a few scenarios. 1) rev a bit over 1000RPM and then seems to stall but comes back to life and rev up to 1000 again and keeps repeating until it eventually stalls 2) starts at a low idle and stalls 3) I have had it start and run fine since I soldered the ground but those are few and far between.

The air temp sensor is bad, I have a variable resistor wired in with no change. I replaced the coolant temp sensor because I thought the resistance was too high, but it measured fine when I removed it. So either I wasn’t paying attention or it was an intermittent.

So to my main question-I want to test the MAP sensor in the computer, but I can’t find any pressure/voltage specs. Short of buying another ECU or finding another car I’m outta options. Does anyone have info to test the MAP?

 

I dont have those values.

But

Your year model would be a 6CU ECU, and they were/are well known for dry solder joints throighout, some you have found. The later 16CU is a pliug and play unit, and advanced in many ways, and way more reliable.

I would splice that Orange wire FROM the Fuel Pump Relay, and earth that splice. That will have the fuel pump running whenever the Ign is ON, so BE CAREFUL, as it is for diagnosis only in my workplace.

The Vac hose and connections from the balance pipe to teh ECU has been known to NOT hold Vac, and the issues you stated are common to that.

TPS going flaky, or waaaay out of adjustment.
Throttle discs all gooed up with Jag Black Goo.
AAV having a bad hair day, more common than most will admit.

Your emissions "stuff" is old now, and maybe reek9ng havoc, I dont know, we No Got that stuff until late 1988ish.

Follow the CTS wiring down the B Bank head, and the splice for teh ATS. Open that oom and check the possible LOUSY solder joint/s. Most I have dealt with a worse that 1st year apprentice stuff.

Check the shielded wire from the AB14 to Pin 18 of the ECU. Continuity of the THIN inner wire, and then inner wire to earth, looking for zero to earth. Main area is behind the engine near the heater tap and stuff.

 

Thanks for the reply. Most of the things you mentioned I actually had intended on checking last night, but I got sidetracked with concerns about my fuel quality. So I drained the tank and flushed out the fuel rail the best I could while trying to disturb as little as possible.

I have a little more info I should share. It hasn’t been very useful to me, though. I hooked up a noid light so I know I have injector pulse. However, I didn’t check them all.

I don’t quite understand why it has two fuel pressure regulators but, I have about 40psi in the rail so I should be good there and at least the return side regulator should be fine.

I scoped the secondary ignition and I’m gettin 23kV- 28kV. The spec I have is 5-15kV, but I assume that is running. I haven’t been able to get a capture of it running yet so I’m not sure if my high cranking voltage is indicating anything. The rest of the waveform doesn’t look that great to me either, but I just got the scope this spring so I got a lot of learning to do. Someone has changed the coil wire and one plug wire at some point in the last 40 years.

I can get it started on starting fluid every time although it doesn’t run great on account of only spraying one bank at a time.

So I got spark and fuel. Although, I still question the quality of each. As far as air goes-I can’t remember if I messed with the air valve in the past. I seem to remember having to raise the idle slightly to keep it from stalling when it was put in gear or maybe it was just out of spec. That would have been a few years ago and I just can’t remember.

I did smoke the engine and there were some switches that leak, but they appeared to leak from a vent so I didn’t spend much time on it.

I’ll check the things you mentioned and come back with some updates.

 

If it starts straight away on starter fuel, then you have a fuelling problem. The FPR on B bank is the one that controls fuel pressure, which should be 2.5 bar = 36 psi. The FPR on A bank is a pulse damper and is better removed, connecting the inflow direct to the rail? The rail connection inflow hose ferrule can be carefully cut off tto reveal a barbed fitting that can be connected to the inflow hose with a fuel pipe clip to hold it.

I suggest you clean up the connector to the resistor pack, if you have not already done so:
https://www.jaguarforums.com/forum/x...sistor-134745/

Also, you can pull the front two injectors and with the help of an assistant, get the helpr on the starter and point them into a jar and see if they are squirting fuel.

 

Following on from Gregs advixe, and adding my findingd.

I am typing this as I think of them, so NO chance of order.

Fill the beer fridge, the reason be obvious soon enough.

Replace ALL 13 HT leads.
Replace the spark plugs, BPR6EF, and gapped to 0.025", and near enough will NOT cut it. Remember the Anti Seize smear on the threads, and dont be stupid with tightening them, just a NIP after taper seats in the head.
Replace the dizzy cap and rotor, and while the rotor is off, a few drops of ATF down the centre shaft hole. A seized dizzy advance shaft is on the cards here. Many threads about that sucker, but ATF and a beer or 3 does wonders.
Read the stickies at the top of this section, another beer or 3.
I have attached the FPR delete PDF for you.
I have many, too many, PDF \'s on this car, so ask and I will post of I have it, or write one IF I have done what you ask.

DO NOT over think things, these are SIMPLE cars, refer to the beer fridge.

INSIDE that AB14 Ign Amp on the B Bank inlet manifold, is a noise suppressor condensor thing, duh, remove it, and move on, there is NO noise, never was. That sucker reeks havoc with the Ign System now its Old.
Look carefully at the EFI loom, in the Death Valley of the "V" mainly, look again, as it is possibly toasted, and doing anything BUT trigger the Injectors. Rebuild it, properly, and repeat in 30 years or so.

Your market has emissions junk, we dont, so you are at the advice of fellow USA members. What little we did get, went in the bin on day 1 of ownership of all my V12 cars.

If you want to test for spark, DO NOT have any spark plug removed from that engine, use ANY old sparker. Engine fires are too easy, always remember that PLEASE. Refer to the beer fridge.

There will be more, and I will add as I think of them, and read your progress.

More thoughts.
Clean the V12 Black Goo from both throttle bodies.
ECU failure is RARE, but solder issues is stepping in that direction.

I forgot that PDF, here it is now.

 

So I think I have a little good news. I started checking the "ECU Ground" test sheet. The coolant temp sensor was open,then i wiggled it and I got a reading. The connector is broke so I got a new one and soldered it in.

Now it fires more constantly and fires up every time(at least as far as my testing can confirm TODAY.) I still have an rpm flare up to 1000ish and stalls or low idle until it stalls. But before I was lucky to get it to fire.

Here are my results: All ground tests to G1 are good I also tested with a test light. Air temp sensor is high 4.3k, but it acts like there is a capacitor in it as it lowers as i measure it. The original sensor is stuck at 4.6k Ill have to check it on the voltage.Throttle switch closed and open are both 8.9 which isn't right.

The throttle position sensor closed and full open are 1.4 k and 3.7k respectively which is way off of the 200 and 2000-2400 my spec shows. Im not sure what "supply" is but I have 3.9k and it's suppose to be 2400-2600. I checked at the sensor and its about the same. I think my TPS is bad too. Can I get a new tps? Having a hard time finding one. I'll report back when I have more info.

If you know what I can replace the TPS with please let me know.

 

OK, the mud clears a tad.

The ATS is basically a "trimmer" and thats all I know of it.

The attached is my TPS adjustment I wrote a good many years ago. Followed by MY replacement, also a good many years ago. There is a Hall TPS available, and Greg has that and the set up when he wakes up and drifts in.

I dont recognise those Ohm readings, never did as such, so the "old mans way" is all I know, and it works.

These are SIMPLE engines and SIMPLE systems, so simple thoughts etc are all that is needed. Over think a 5.3 HE, and you are doomed.

Years of "I will get to that" is the 100% reason these beasts are as bad as they are, so ONE thing at a time, get the simple stuff up to snuff, spark plugs, HT leads, etc etc, and then see what the thing is telling you, and sadly, fancy test stuff will confuse the issue. I was taught to listen to the engine, it is full of info.

 

Forgot.

Remove the dizzy cap, carefully, look at the spring loaded carbon brush in the centre of the innards of the cap.

1) Is it still there.
2) Is it burnt away.

They burn away due to wrongly gapped sparkers, OR fancy "special tipped" sparkers. Normal standard BPR6EF is their preferred diet. Gapped to 0.025".
They fall out, gravity is a pest.

They WILL start and run without it, NOT VERY WELL, and do strange things, FACT, as 2 of mine did it.

 

Do your spark plugs have a small “V” machined in the electrode?

This tune up is becoming overly complicated. I have the parts…kinda. So I have a cap made by Standard and a rotor by Wells. Those seem to be my only options. If you suggest anything else I’m all ears. Wires are NGK.

Now the plugs are weird. I can’t get BPR6EF in the states. After talking with NGK, those plugs are in the Japanese catalog-so available pretty much everywhere but USA. He said the BPR6EF comes in two versions 1) with a removable nut gapped at .028 and 2) with a solid nut gapped at .036. Both those versions he said should have a “V” groove in the electrode. And they would have only been available at a Jag dealer here in America or overseas. I tried some dealers and they want nothing to do with looking anything up for this car. We have a BPR6EFS which has a standard electrode(no “V”) and is gapped at .032. I can’t imagine why those won’t work, but I plan to order the BPR6EF from the UK after I hear back from the seller.

One more piece of information for someone in the future-the parts stores and NGK both list a TR5 for this car. NGK said NOT to use it as it comes gapped at .040 and to gap at .025 would be altering the gap more than they recommend and I believe he mentioned something about the design of the ground strap and electrode too.

Just to circle back on a few things-I don’t remember any black goo. I’m pretty sure I cleaned the throttle bodies already but I’ll double check. I don’t remember anything out of the ordinary when I had the distributor cap off so I’m pretty sure contacts are good. The rotor was seized on the shaft and I couldn’t get it off so I left it until I had the new part because I’m pretty sure it will break coming off. I also believe the advance is seized because I don’t remember any movement when I was trying to get the rotor off. I’ll get the resistor pack cleaned today. You also mentioned “stickies” I don’t see anything like that, but I’m on a 10 year old “smart” phone so maybe I need to log in on a computer.

I think I may get the standard electrode plug while I wait for the others to ship, but let me know your thoughts. At least that way I can keep working on this.

i immensely appreciate all the help! Just gonna take me a little time to get through all the suggestions.

 

Again, typing as I think of things, ts an age thing, we all get there at some time.

Bugga on NGK. I been in the Auto Parts Game since 1966, and KLG was the only sparler that was in 2 bits, used mainly on the Side Valve Ford V8's. BPR6EFS is FINE. That is their "standard" spec plug, NO "V" in the centre electrode, simply re-gap them, carefully, to 0.025".

I used Echlin, EP64 and EP65 for cap and rotor. Echlin USA was here years ago, then packed up and left??.

Stuck rotor, welcome to the V12 family. SO NOT, repeat, DO NOT simply pull up on that sucker, you will DESTROY the innards down below. I use a Dremel and carefully cut away the old rotor, remember the beer fridge, haha, and then drop some ATF down the hole, and a smear of same on the rotor shaft area, just because. That Dizzy and Coil, etc all get absolutely fried in there, and thats another thing to look at a little down the track.

Vac capsule will be toast, will not stop it starting or running.

My dizzy shaft PDF and a few others attached.

X
Stickies are at the top of this section.
Phone, oops, thats for phone calls, or am I wrong??? I know, but the Laptop is my means of doing this stuff. Bigger screen for my one working eye.

Dealers etc for Classic Jags, and anything really, waste of time. A parts car is becoming more popular than ever for many.

 

Well, Grant, your advice was terrible! My beer fridge is empty, my wife won’t touch me, my parts guy had to help me push this whale in the shop and…well actually I switched to something more aggressive than the beer cause I ran out. So Nevermind….good advice but bad decision making on my part. All I know is this has champion plugs rusted so bad that I have to hammer a socket on them or they round over. Probably shouldn’t waste the time posting but I want to prove to you I tried using the fridge. Will let you know tomorrow how the tune-up went if I can manage getting all these junk plugs out.

 

HA, topped mine up today, the X Type is consuming more than I like.

Take your time with those plugs, PLEASE, as snapping one off will cause major PAIN, usually a head off, which means engine out, and a loooooong list of "while I am in there" that the wife will LUV.

Mix up a brew of ATF and Diesel Fuel, 50/50, pour it in the wells and go away, Vegas or such for a few days. It worked for me years ago with a Pre HE "thing", and Vegas was good.

Some have mentioned drilling out the snapped off bit, OK, whatever rocks the boat, NOT for me. That swarf has to go somewhere, and gravity is very eager.

 

So a bit of an update….I’m pretty excited that I think I figured it out, but I’m preparing for the disappointment that I'm wrong.

Finished the tune-up. New NGK BPR6EFS gapped at .025. New wires, although I’m pretty disappointed with how they look. The new wires had some 90 degree boots and the old ones I pulled off were all straight. Only about 3 wires match for length so fitting the wires to the correct hole tested my patience. Instead of spending hours moving them around I just made it work. The advance is stuck so I figured that can be a project for next year and I’ll try and reroute the wires then.

As I anticipated it didn’t fix the problem. Still has the same symptoms. However, it definitely fires WAY stronger! If fires up every time and I can hear more cylinders firing more consistently.

While my son was cranking it I was doing the old “tap test” on the ECU with the covers off. And when it would run I’d tap it and it’d stall and when it was stalling I’d tap it and it would run. Could be coincidence, but I did it enough that it seems to be an issue on the board. Probably more solder joints I can’t see. BUT the best part was when I pushed hard enough to distort the board it fired up and ran fine and after a few seconds of holding it that way it stayed running and I could release the pressure and drive it.

So I’m waiting for a 16cu to get shipped to replace the 6cu. I’ve been trying to get it shipped for a few days but it’s kinda like herding cats trying to deal with these guys. Maybe I’ll have it this weekend and I’ll update you.

 

Great news, she lives again! With the used 16cu it fired right up.Throttle was a bit doggy, but I forgot to plug in the throttle position sensor after I tested it. Oddly enough it seemed fine after I plugged it back in even thought it was like 3000-4000 ohms out of spec. I can't explain that.

I still intend on doing some more diag on the map and old ECU and post my results for anyone that is curious. I might have him bring it back for that in the spring though.

I can't run it too long because the oil leak on the left side smokes so bad I'm afraid it's going to catch fire.I can't really tell if its coming from the cam cover or just below it and from what I remember the underside of the engine is pretty well covered too. So my next question is how do you recommend cleaning this engine so I can diagnose the leaks better? I've powerwashed engines in the past, but this doesn't look like a candidate for that. I was thinking about hitting it with a few cans of degreaser and rinsing with a hose, but I wasn't sure if that's a great idea either. I could also hose it down with 100 dollars of good brake clean and just wait a day to start it up, but I hope you might have a better/cheaper suggestion than that.

Thanks for all the help bringing her back back to life. I suspect there will be some much needed maintenance/repairs it will need after being neglected for so long so feel free to let me know.

 

Well done.

Yep, they will start and run without the TPS, been there also. Dont over think it, its plugged in, the Cat is happy, move on I say.

 

Cleaning the engine: DO NOT HOSE IT. The only safe way is carby cleaner and a SMALL brush and do a small area at a time. Plastic bag over the dizzy and taped round the base. Then compressed air to blow anything away.
The cam cover and the tappet block are almost certainly the leaks. Nothing for it but to remove the manifolds (as a unit) and redo the gaskets and clean, prep and seal round the tappet block/head seam. Like this:


The orange stuff seals the tappet block to head join.

Induction can come off as a unit

Once the induction is off, the V can be cleaned and the cam cover gasket done. Worth changing the oil pressure senders while you have good access too. They also can leak after a while. BLOCK ALL HOLES and do NOT remove the plugs until all clean, only then renew them.

 

Forgot the rest of the ask. thanks Greg.

YES, no hose, no silly actions.

At the rear of the head/s and part of the camcover seal, is a "D" rubber plug, they leak, BAD.

BUT

Just below them is the Banjo bolt for the cam oil feed,
DO NOT TOUCH THAT AT ANY COST,
They rarely leak, I have never had one, and if that Banjo bolt is "I will just nip that up a tad to be sure", it will strip the alloy threads, THEN, its engine out to rectify.

AND

At the oil filter housing, there is a SMALL steel pipe, looks like a walking stick, with a 1/4" hose and clamps on each end. THEY LEAK BADLY. With Cats, LHD, I dont envy the access. Being we are RHD, and NO cats, access is TIGHT, and "feel" is the way to go. Oil filter removed helps a tad.

Have fun.

 

To continue the Franco/Oz double act, this:

 

That looks exactly like the leak, Greg. Kinda like the idea of smearing the sealant instead of tearing the timing apart to change a gasket. I really don’t want to get into that now, but it doesn’t look too bad. How long you think it’d take a first timer to pull the manifolds and do both sides?

 

Great info in this post....thanks all.
Rob