Hi friends,
just for fun and because I don´t know what to do any more... I made some research:

One video attached shows my CPS-signal while cranking. Seems fine to me.
The other video attached shows my sparks. One plug wire (3A) and the HT core wire to the dizzy´s B-Port. Both fine to me.
If CPS is disconnected - no spark either.
So I am quite sure... sensors and spark/ignition (if not timing) are not my issues.

Tom

 

Hi Tom

Looks like a really good Spark you've got there and the CPS seems to be working

Where the only thing I can think of at the moment, is that the Fuel is refusing to ignite and all I know about Xylene is that one of its uses is for thinning Chlorinated Rubber Paint, so wondering if you could get some Carburetor Cleaner into the Fuel Rail, just to see if she will fire on that

Alex

 

I do have another question concerning the earth of that ECU-wiring and maybe someone has already examined this.
The Jaguars wiring diagrams name each ground point. Therefore you know which ground a specific circuit uses (e.g. G1 till G16).
But the ECU diagrams names the ground "IGN.". But the ignition does not switch any ground, or does it? I am confused...



I assume the ground quality here is important.
As the amps and the coils have static 12V with ignition on, the spark pulses are driven by a ground drain.
Does someone know where this "IGN." ground is?

Tom

 

Still no start. Same Behavior: cranks good, fires really seldom up a bit, but does not run.
Has pulsed fuel injection (tried even start pilot), has spark and good CPS and FWS - resetted and swapped. Timing is set all correct. 12V on white wire and on ECU, Grounds are perfect. Compression ok. Checked whole ECU-cabling from all sensors to ECU. Swapped rotor and dizzi. No coil mismatch. Spark plugs are really black. Neither bank starts - same behavior (cranking and very few ignitions) if I disconnect one bank completely.
No ideas left...

 

Captain obvious here... Apologies in advance.

Something simple is amissssss... Has to be.

Since work has been done on those signal wires from the front and rear crank and fly wheel,,, must/might/could be something there.

Then,,, I imaging I would be leaned over the engine visually, with a pointer, following each HT lead from the dizzy to individual plugs... Gapped correctly, yes?

Is your tachometer and speedometer JUMPING when you turn the key? If not, something there...

Maybe you've said,,, but have you REPLACED the CTS on the left hand side of the motor?

The fuel injector wiring loom. Have you had it OUT, on a bench, apart, inspecting all of the wires for short? ESPECIALLY the grounding joints. There are several of them.

Is the resistor pack at the front right hand of engine bay known good?

This is just me,,, I think testing things with a meter can only go so far... I admire your troubleshooting skills, goodness knows I wish I had half of the patience you have when it comes to this sort of work, but at the same time there is something to be said about the physical 3D touch and feel of all this that is very useful as well. Please don't take that in a negative way. I have beat my head in a wall simply because I could not/didn't know how to do the diagnostic trouble shooting - but do usually find the issue with good old fashioned hands, eyes, ears and "feel" as GF says sometimes.

The AMPS,,, what did you say about these? There are cheaper replacements than the super expensive genuine Marelli brand. Try that?

It has to be right there...
Again, Captain Obvious...
Keep it up...!

If you are KNOWN to be getting spark, fuel and air (on time right time) you should get run. Somewhere somehow you don't have that.

 

Have you set up a know good heavy gague wire from say your alternator bracket to a good solid ground to make SURE the engine block is getting good ground?

Is the fuel pump really and continuously running. Have you sprayed ether or some other good combustible into the Throttle bodies when test cranking to see if it will soon over better on a introduced fuel? This, maybe with the FInjectors disconnected...?

 

Hi Jay, hi friends,
and again a couple of hours spent this weekend without an approach.
> ...set up a know good heavy ... wire from... good ground
Yes Jay, I thoght about that, too and tried this directly from the battery to the engine block. Unfortunately no difference.

All fuel related things I do no investgate further because...
...some friends were coming around for a barbecue tonight driving an 1990 XJS V12 Coupé. We stopped the injectors and had some dry runs to get off the fuel a bit. Then two guys used start pilot (a combustible) on both opened butterflies - not a single start appeared.
Must be something with ignition we concluded.
I bought such a spark tester with two cones in it where you can set the distance to check wheather the sparks power is strong or weak.

Then we concluded: if we have fuel and spark and compression - ignition timing must be bad.
But we did not find any good reason why or how this could happen?

> ...The AMPS,,, what did you say about these?
I have a spare car here and swapped them - no difference. Because both banks behave quite the same, I suspect something affecting both.

> Is your tachometer and speedometer JUMPING when you turn the key?
Tachometer: yes - this is drive by the A coil (ignition), Speedometer no: this is attached to the transmitter at the diff.

quite disappointed greetings from my garage
Tom

 

Hi Tom

Are you absolutely certain the Timing is not 360/o Out as it has been known to happen and also there is not much left to Check apart from the possibility that the Engine may have got flooded if the Plugs are Black

 

Ok... What were the results of the spark tester?

Just so I'm clear,,, you sprayed ether, or some combustible, into the butterflies of YOUR car (the one that you've been working on) and the car didn't even sputter? No ignition of the ether, combustible, at all? Makes no sense...

Are you SURE the spark plugs are firing? Like, sure sure...?

The last time the car ran (you have had it running before, correct?) Was there a timing issue and, if not, have you done anything that would have altered the timing? Are you SURE you have the correct Marelli distributor? The correct rotor?

Did the motor get spun (with a bar on the main crank bolt) backwards???

Something isn't adding up here...
Something is being taken for granted OR overlooked, or both, lol...

This has GOT to be driving you nuts, Good Brother.
​​​​
​​​​​​

 

From your first post...
I would reinstall ALL of the old HT leads....
New **** doesn't means good ****, always

Also, are you sure BOTH of the coil to dizzy leads, the short ones, match the type of coil plug. Meaning there are more than one kind of coil to dizzy kind of connector. One is basically a barrel shape and it makes contact by a kind of pressure fit where the walls of the barrel of the HT lead are pressed by there shape into the walls of the dizzy and coil connector... The other is a PIN kind of contact where there is a pin (usually on the coil side) that an EXACT right shaped barrel on the HT coil lead has to clip into/into. I hope that makes sense...

One time I ordered a new coil set and the coils had (and still have) pins in the connection port. I had to call the manufacturer and the guy made me a "special" set of HT leads. On the coil end it has a clip on barrel that clip and needs to be pushed down and over a PIN In the coil connection and on the dizzy side it's the more traditional where the side of the barrel on the HT lead pushes OUT to make contact with the walls of the connection surface of the the distributor connection orifice...

If you let me know that description makes NO sense (which is very possible) I'll Google and find some pictures, lol...

 

Again and again - my stupendous thanks to your help here!

I will try to figure out, where the devil might caught.
> Are you absolutely certain the Timing is not 360/o...
I am not really sure what that means, but I assume you mean 1A is at highest position when the finger is pointing straight to the radiator, when TDC should be, BUT here it is between stroke 4 and the new 1, meaning exhaust gas is pushed outwards and the cylinder is about to suck in gasoline? This is not my problem - I´m quite sure - as I´m able to see the exhaust valve opening and closing and therefore I know (see) the difference between stroke 2 and 4.
> apart from the possibility that the Engine may have got flooded if the Plugs are Black...
Maybe we approach a solution here. Even if I don´t have a clue now. Fact is:
Injectors are running clocked. You can observe them pulsing. I have tons of fuel. You see this with the pics above (beakers) and the garage smells gas.
But... sparks are rrreally black. I cleaned them when I measured compression. And the cylinders are full of black debris. I mean... sparks are not dripping though, just a bit wet and rrreally black. I thougt this is just gas from injection beacuse it doesn´t fire up.
But... too much gas makes a sense when I told you, it begun all with bad firing up.. only with open throttle and always took a while to get a stable idle when warm.
I will check here closer next days.

> Ok... What were the results of the spark tester?
This one is still on it´s journey to me.
> sprayed ether, or some combustible, into the butterflies of YOUR car ... car didn't even sputter? No ignition ... Makes no sense...
Correct. We even cranked a while with injector loom off before doing this...
> ...The other is a PIN kind of contact...
Yes, yes, yes - Your are a genius Jay!! There is one coil within my spare set which is a pinny one. Big surprise for me a couple of days ago. But those I use right now are the good ones. This is weird though.
> I would reinstall ALL of the old HT leads....
I certainly could do that. But the old set is not numbered. I first have to figure the right wires.
> have you done anything that would have altered the timing?
I even do not know what I could have done with this...
> Are you SURE you have the correct Marelli distributor? The correct rotor?
Yes, at least I have the old stuff and some new stuff here. Okay, I did not reinstall the old finger. Might do that.
> Did the motor get spun (with a bar on the main crank bolt) backwards???
You will not kill me for that??
Maybe. But 3-6 months ago. And meanwhile I drove around here in April. And I am really sure: at TDC the finger points 100% straight north.

Have a good that this week,
Tom

 

On a Marelli car, often, the numbers are labeled on the top of the distributor. The numbers on the leads are just to help with lengths and placement in the installation... If the TOP of the distributor is labeled, have you gone in with a pointer of some sort and visually checked that each and every lead is going from what is labeled on the top of the dizzy to the appropriate plug?

I would stop fueling, as OB said, flooding and fouled plugs might be a problem now. I think all plugs might need to be removed if everything is as blackened/fouled as you say, cleaned or replaced (a bit of fine sand paper and/or some steel wool and solvent) and when cranking ONLY use the strat assist/starting fluid until you get some signs of life...

With plugs removed, plugged into there leads, do one more check for spark, with the fuel loom disconnected. Reinstall clean/new plugs and use fluid the try for signs of life/ignition test cranking with fluid...?

I'm not sure what else to say. I'm certainly no expert, certainly no genius... This is all strange.

 

Hi Jay, thanks again...

> have you... checked that each and every lead is going from what is labeled on the top of the dizzy to the appropriate plug?
Certainly. About 60 times last 3 weeks.

> ...plugs might need to be removed ..., cleaned or replaced ... and when cranking ONLY use the strat assist/starting fluid...
Promised. Will do so.

> I'm not sure what else to say...This is all strange.
Congrats. You arrived at my stage.

Pray for me.
Tom

 

Hi Tom

Did you ever remove the Distributor?

If you did without 'Marking' it, then there is a possible chance that the Timing could be out by 180 degrees

Has any Petrol found its way into the Oil Sump and is the Compression really good or just about ok

Definitely worth considering a new set of Spark Plugs at this Stage just the ordinary NGK ones as the XJS does not like anything fancy

Also very much agree with 'Jay' something is very wrong here, disconnect the wires on the Fuel Pump or remove the Fuel Pump Relay and try and get her to run on some 'Carburetor Cleaner'

I could be wrong but the Timing sounds most likely

 

That... it was.
Just left the car standing for 4 weeks. No "Good Morning", not even a view.
Went into the garage the day before yesterday.
Pressed down throttle fully to get max air.
First 6s cranking - nothing. Just spinning. Not a single explosion.
Second 6s cranking - a couple of firing cylinders.
Third 6s cranking - a short firing up of the engine.
Fourth 6s cranking - engine fires up goes immeadeately to x000rpms.
Let it runnig with 2000-3000 rpms. Garage was fully of smoke, I hat to cough hardly... but I did not want to let it die.
After 30s it was that stable, that I might let the gas come to idle. So it run for 20mins then.
Now it´s reborn. Still the bad cold start behavoir (probably too rich), but starts up reliable.

So cute to drive with...


Tom

 

Change them plugsChange them plugsChange them plugsRight gap! I think it's .025

I was told by one of the guru's here that these plugs rarely UNfoul themselves... I was hard headed (as I am) and learned that it's true. Change the plugs or at least remove them and clean by hand.

 

Ok... I just skimmed this whole thing from bottom to top and I see 3 issues, one of which hasn't been mentioned.

1. Trivial. The timing can't be changed or f'd up on a Marelli car without changing the sensor position in relationship to the toothed wheel on the balancer. Moving the distro body just messes up where the rotor contact patch is in relationship to the wire lug inside.

2. That picture of the White coax wire shows a sheathing break exposing the inner wire. Keep an eye on this even if it's not a current problem and/or shrink wrap over it. It could ground out or a stray fray from the shield braid could come in contact with it.

3. Sounds like your non-start issue this whole time was massive over-fueling, and no one has mentioned checking your coolant temp sensor and it's connection (the 2 pin unit on the B bank behind the thermostat).. A bad/corroded/disconnected connection here will cause MASSIVE over fueling as the ecu thinks the engine is below zero cold. Most cars won't start, or do what yours is doing and barely start while trying to clear out the fuel, then run massively rich. Here's a link to check the ohm values of the sensor per temp, but what's really important is how the ECU sees that resistance back at it's end on pins #5 and #19- so check that plug and wiring condition.

https://www.jaguarfuelinjectorservic...e%20Sensor.htm





Other ways over fueling can happen - the diaphragm of a fuel regulator can bust allowing fuel to be sucked in through the vac line. Or injectors can leak down if they've got problems (doesn't seem so in your case).

One test that often gets them started if you suspect flooding is to pull utp the inertia switch which cuts off the fuel system but not the ignition. They'll often fire up for a few seconds as the flooding clears.

Something to look at anyway.

~Paul

 

Hi Paul,
this is really nice of you to look over my thread and give some more ideas and advice.
Indeed I just measured the coolant temp resistance at the ignition ECU. Astonishingly there are the same pins used, as I wrote on 12th of June:
I will test this with the injection ECU next weekend.
Thank you, Paul.
Tom

 

Ahh darn it.. skimming I missed that. There are few other culprits.

~Paul K.