Is a pin out table the same as a fuse box?

 

No.

A pin out table or pin out chart shows the function of each connector pin of an ECU or similar control module

Cheers
DD

 

Hello i am new here and not knowing how to get to the posts Your page is . Very interesting this is why i write to you since you are in the know for these cars.. I have an issue with mine. (1989 xjs conv) But didn't find the answer .Was starting just fine all the times, but now it is slow to get to the running speed. it seems that cylinders are picking up one after one.right till the 12 cyl are in. Then all is ok.Fast idle comes on for some times then idle gets normal for a few time. maybe 1 or 2 minutes.then it start to hunt going between 500 rpm to 1500 rpm. If i put it in gear all is ok and i can drive the car as i wish.if i put it in park or neutral the unting resume. can you help on this issue? Thanks. Yvon

 

Hi.

First I would strongly suggest to STOP driving the car for a while...

Second suggestion is to begin a NEW/FRESH thread. A thread of you own. Meaning go to the main XJS forum page and click on new topic, and start a discussion of your own about your issues.

Jus say'n.

 

Yvon,

Welcome to the Forums. When the nerves settle a tad,please do an Intro in the New Members Area.

OK, that list could be very long.

As Jason mentioned, a seperate thread of your own would be really easy to follow.

Some things need to be established FIRST.

1989 is a model change. You hear of Lucas, and Marelli Ignition systems. VERY different trouble shooting for each.

Please count the Spark Plug Leads, the thick ones.
13 = Lucas
14 = Marelli

Once this is established, the work can begin.

I agree with NOT driving this car at the moment, your market has Catalytic Convertors, and engine issues like you describe, CAN cause an engine fire.

I DO NOT WANT TO SCARE YOU, just please play it safe.

These are SIMPLE cars, and easy to fix ONCE the basics are known and a methodical approach is followed.

I await your reply.

 

Hello thanks for your answer. And the ignition system is LUCAS.

 

THANK YOU for that.
Lucas is easier by a long stretch.
Reading all this again, the engine starts, and slowly takes up all 12 cylinders, not good, as you know.

Over many years with these I suggest the following as a starting point. I know you are a mechanic and I mean NO negative attitude at all, just I work systematically with these engines, it saves time. So, if anything I suggest is "done" ignore that suggestion.

1) Spark plugs, age, and correctly gapped at 0.025".
2) HT leads, average in that engine bay is 5 -8 years.
3) Dist cap and rotor. NOT a common issue, but age again is against the original.
4) Coils. You have 2, one in the V, Main, one out the front as a "booster", for want of a better word. Check the Ohms, +ve to -ve, NO other wires attached. Looking for about 1.2 each coil. Connect the "booster" to the Main with the loom provided, read the Ohms again, looking for 0.6ish, and no higher than 0.9.
5) Inside the Ignition Amp is a Condensor. Remove it, it is redundant, and reeks havoc.
6) The TPS (Throttle Position Sensor) may be out of range. It will NOT cause the odd start up, just mentioning it as part of the checking.
7) Check the volts at the White wire at the +ve terminal of the Main coil. Ign ON, should be battery volts, or close. Read again as it cranks, should NOT drop more than 1volt, give or take.

Concentrating on the odd start up, as in one cyl and more cutting in as it warms up, then settling down to all 12 cyls.
Injector pulse is erratic. Can be caused by:
A) Grubby plug and socket of the EFI Resistor Pack. Located in the engine bay, RH front corner, near the radiator RH tank. I use lemon Juice to clean those items, and rinse with WD40.
B) EFI loom, the one in the bottom of the V. Age is way past use by date for this, and erratic Injector operation is almost always this loom. Make a new one, simple enough, although time consuming. New looms are out there, I have NO knowledge of their quality, always make my own.
C) Engine earth strap fiasco, Run a dedicated earth lead, engine to chassis. The factory twin braided nonsense, is just that, and age again has it reeking havoc.
D) Main EFI ECU, in the boot. Unplug the multi pin, clean it as with the Resistor Pack, and replug. Check the small Vac hose on the side, they crack/split, and cause all sorts of issues. Some markets have a Black Plastic "filter looking thing" in that Vac line (usually just under the battery). These also crack, remove it, run anew small Vac hose frron the floor spigot to the ECU.
E) Spark plugs, as mentioned.
F) HT leads, also mentioned.

The AAV, you have addressed, will NOT cause erratic start up as you describe. It is simply an Air Bleed device for Extra Air at Cold, and then Air Bleed, via the 13mm hex bolt, for HOT idle adjustment. If it jams OPEN, then the bouncing HOT idle is always going to happen.

A few attachments that may help.

I will keep thinking as I play with my mighty X Type.

 

Thanks for all this procedure.Every parts that pertain to the ignition system are new. BUT i am glad for all the information you gave me.I will print the list and do my homework.My chevy friends tell me to install a V8 ha ha ha no way.Been a Jaguar addict all my life.And with your help she will be back on the road soon. PS maybe you are right for the aav been stuck.13mm adjuster have no effect on the Hot idle adjustment.Will have to dismantle to check it in boiling water to see if it closes when hot. Thanks and goodbye. Yvon

 

Just to tell you of a detail i forgot. My wife (50) years this summer remembered me that this issue appeared just after i changed the Prestone in the engine.Maybe it will help.She also told me the same thing happened 4-5 years ago in the same situation,but this time it resume to normal after some times. Regards. Yvon

 

MMMMM,

Not familiar with Prestone.. Know the name (Google) and its a coolant Brand up there.

I dont see the relationship of coolant and erratic cylinder firing at start up.

OK, Air pockets in the system on any V12 is a hassle, but that is Temp related generally. AKA floating temp gauge etc etc.

A big enough air pocket, and the AAV bulb will not be sitting in liquid, causing it to not operate. Same would apply to the CTS and Temp Gauge sender, they all need to be immersed in liquid to operate, they cannot read steam, as we all know.
BUT
There would be many, many other serious Coolant/Temp issues with that engine other than an AAV not working. Also having no relation to erratic cylinder operation at start up and then sorting itself out as it warms up.

Lots of things are bouncing around my very old brain, and most are related to the WHOLE system, not individual cylinders, that fault comes back to spark plugs, leads, cap, Injector Loom, only.

Spark integrity creeps in to my thoughts. Check the spark at any plug, and ensure you have a FAT, CRACKER of a BLUE spark. Without that Cracker, that engine is in trouble.

Clutching at straws a bit with this one.
One of mine had issues, mainly not revving, and eventually I found the New Cap and Rotor (Echlin USA Brand) were out of spec slightly. The spark out of the end of the rotor was coming out of the top face of the tip, NOT the end face, and arcing to the very bottom tip of the related probe inside the cap. I like the arc mark in the middle of that probe, so I installed a fibre washer inside the rotor, thus raising in about 1.5mm, removed the cap gasket to lower that cap about the same mm. Checked that arc witness again after a few hours running. Sweet as I would want, and NO issues at all with the engine. That was 22 years ago, still OK.

 

Hi, I am new here, and has just acquired a 1985 XJS V12 HE.

I was reading through your notes and found something new about the condensor in the ignition amplifier..
I have a Lotus Esprit, which also has a similar ignition amplifier.. I had some issue last year with starting the car, and solved it by replacing the amp and condensor in the amplifier.. I had a hard time finding a replacement for the condensor!
However, I never realised that we can ditch the condensor, and the car will run better without!

Thank you very much for the great writeups..

I am eagerly waiting for the XJS to reach my country..

Cheers!

 

well after 1 year of rebuilding deleting stuff I tried to start today with no avail. so printing this list in hopes of find the the reason. It cranks but just wont go. I do see the tach jump up for a split sec to 1k then back down when trying to start. I did briefly test random stuff like, check an injector for 12v (1B) and it did, I know my fuel pump is working, fresh gas.

one note is I did check the throttle capstan, manually rotated it, I did not here the injectors click. only clicking was the kickdown switch by it. So I think the TPS might be the issue. I'll dig deeper tomorrow on that. the day is done.

 

So I tested the tps. There are 3 wires. Red white green. The yellow wire never moved from .02v. The red wire was originally at 1.20v and I was able to adjust this any direction. I set it at .36ish. Very finicky to adjust btw.

I didn't test the green wire. No mention in the document.

reassembled and could now hear the injectors clicking when i moved the capstan. So tried starting it again and nothing.

But maybe it's because the yellow wire got now change in volts?

I'll wait for opinion before I ordered a new tps.

 

OK, some good signs.

I have never done the single wire TPS test. Always the split with the ???Red Green (memory is getting damn scary), anyway, 1 is the 5v feed FROM the ECU.
The fact you are .36ish and have clicking, good to go in my opinion.
REMEMBER, that engine WILL start and run with the TPS unplugged, just a mongrel to drive like that.

CTS bridging to fool the ECU is always a #1 or 2 on the list.

I know there is a bucket load of noise when cranking, BUT the Injectors should be clicking during cranking. Reach in with those loooong arms, and feel an Injector whilst cranking, you will feel the clicking.

If no pulse on crank, then that infamous Shielded wire is getting high on the suspect list.

I am assuming you have Spark???, Get someone to hold a lead while you crank it, the distance they jump gives an indication of the quality of said spark.

 

so first in list i checked fuel to rail. passed

2nd is tps. like mentioned even if disconnected or not correct engine should still run yet badly.

red wire is the one that changes.... currently 0.7 volts (needs adjusting)

yellow wire is ground

green wire is constant ...currently at 4.4v (should be up to five but i read as long as its close its good

so now i am thinking no spark. next on list

how to bridge cts?

​​​​​​​

 

just pulled the 6B spark plug. looked a little wet and smelled of fuel.

waiting for my wife to get home so she can crank the engine while i check for spark

im gonna check a few more things wire wise while i wait

thing is i dont have a spare spark plug

 

Wife had lunch duty so not home. So no one to crank while I check things. I did jump the cts and no change.

Testing the sensor itself I have 2.3k ohms across the terminals which is good for a cold engine

Ill update once i get a 2nd pair of hands

 

Grant, if you are still active, I have been studying your guide to get my 91 XJS12 started up. USA Left hand Steering. Testing the Injector connections on both LH and RH. Your write-up suggests both Pins should be in 12volt range when tested to ground/earth. I can get one pin on each connector to show reading of 12+ volts but the other pin is not showing such. LH alt pin shows 1.8v. RH alt pin suggests Zero with my DVM.

 

yes my 88 v12 both test 12v each pin. grant can confirm when he wakes up.

 

so my results for todays testing.

also bought a inline spark tester

ill start at the beginning of the document:

fuel system section:

pulled fuel line - turned on ing. pump squirted fuel well.

pump works fine (replaced relay last year) works as intended

fresh gas yesterday. 10L 91 Oct with oct booster added for a little extra oompf

new fuel filter replaced a few days ago.


EFI electrical issues

I suspected this is where the issues lies

fix the TPS so now when i move the capscan i hear the injectors click. once

right now tps gets 0.7v at idle and 4.4v at full throttle. will adjust later but wont affect startup

i removed spark plug 6B. is a little wet and smells of gas.

i put spark plug back and install inline tester.

turn over and there is a spark. but engine is still struggling.

i test the CTS. test results are 2.3k ohm which is good very cold engine.

i jump the CTS anyways and no start.

I test the single ignition coil. have battery voltage, crank engine, it drops about 1.0v. no more.

i test the ohms. .70 to .80.

so i didnt test everything as i am going to have to create a long jumper to check the pins at the ECU etc.

so everything i tested passed.

so then im sitting here and im like i only tested one of the connectors in the injector loom which i rebuilt. i tested the 1B one. 12v each pin. so i skipped the rest.

well now i decided to test the all. start on the B bank. all 6 have 12v to each pin.

onto A bank. I test the first one. one pin has 12v the other pin has 0.1v. I test the other 5. all of them are one pin is 12v the other is 0.1v. and 3 of them are opposite of the other pins. 1,3,5 are same and 2,4,6 are the same.

So is this my issue. I think so. would the engine not start on only one bank lol?