XJ6 & XJ12 Series I, II & III 1968-1992
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XJ6 Series 3 Ignition Timing.

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  #1  
Old 10-28-2017, 08:42 PM
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Default XJ6 Series 3 Ignition Timing.

Hello there,


I'm going insane.


I've installed a donor 4.2 early Series 3 engine into my 1985 Sovereign after a head gasket failure.


Both engines were running in their respective homes before the transplant.


The Sovereign electrics and EFI stuff were retained as most of it was new and known to be operational. The donor engine originally started, but would stall after a few seconds and would not restart.


Out of desperation I decided to swap distributors over, but now the engine will not fire whatsoever.


I have followed all the necessary troubleshooting checklists, but to no avail. I have fuel, I have spark.


I have turned the engine over by hand to TDC, on the compression stroke, on cylinder number 6 (at the front) and the rotor arm points at number two plug lead on the distributor cap. I have tried swapping the plug leads with #6 lead where the rotor points, but still zero fire.


I've tried everything, not even a misfire, not a hint of ignition.


Do I start at 6 degrees BTDC? Is there a basic starting point for setting ignition timing up so that at least I can get the car started so I can get it to a professional?


The distributor can only go in one way, I put the Sovereign unit in the exact position the old one was.


Is there a compatibility issue between early and later Series 3 engines and componentry?


This is seriously doing my nut in, it's not rocket science and thought I'd covered all the basics.


Any assistance would be greatly appreciated before I'm clinically insane.


Cheers.
 
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Old 10-29-2017, 03:39 AM
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Assuming you have the plug leads in the correct sequence, try rotating all leads clockwise by one. If no fire, then try anticlockwise by one.


I can remember I had this problem years ago. I thought I had the leads in the correct sockets, but the whole set was out by one.
 
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Old 10-29-2017, 04:09 AM
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Originally Posted by The Mekon
Assuming you have the plug leads in the correct sequence, try rotating all leads clockwise by one. If no fire, then try anticlockwise by one.


I can remember I had this problem years ago. I thought I had the leads in the correct sockets, but the whole set was out by one.
I have tried that, going to the extreme of rotating all leads continuously until I returned to the original starting sequence.

I really thought it was as basic as getting #6 cylinder at TDC on the compression stroke and then starting the plugs leads with where the rotor pointed, that is 6, 2, 4, 1, 5, 3 - obviously in an anticlockwise direction?
 
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Old 10-29-2017, 05:38 AM
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Then are you sure you have fuel? Just a little squirted by hand down the intake ports should suffice.


Some years ago I had a problem starting a fuel injected Nissan. Everything was correct and it should have started but did not.
Reason was the starter motor was tired and drawing all the current from the battery on cranking, leaving nothing to get the injection system going. Proved by squirting a little fuel down the injectors, and hey presto - engine fired. In this case the fix was to replace the starter motor.
 
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Old 10-29-2017, 07:51 AM
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Originally Posted by Undertaker
I have tried that, going to the extreme of rotating all leads continuously until I returned to the original starting sequence.

I really thought it was as basic as getting #6 cylinder at TDC on the compression stroke and then starting the plugs leads with where the rotor pointed, that is 6, 2, 4, 1, 5, 3 - obviously in an anticlockwise direction?
I always begin with #1...my brain just works better that way

Anyhow the firing order is 1-5-3-6-2-4

So if you start with #6 wire then your sequence on the cap will be 6-3-2-4-1-5

Cheers
DD
 
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Old 10-29-2017, 08:45 AM
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I am with Doug!


Merely swapping leads even systematicly is fraught with peril and usually works only because of luck. Not that I don't find luck useful.


In time of peril, back to basics. It is the time of peril.


Carl
 
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  #7  
Old 10-29-2017, 08:50 AM
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Originally Posted by Doug
I always begin with #1...my brain just works better that way

Anyhow the firing order is 1-5-3-6-2-4

So if you start with #6 wire then your sequence on the cap will be 6-3-2-4-1-5

Cheers
DD

No no no ! I got that wrong.

This is what happens when you post before the first cup of coffee.

6-2-4-1-5-3 is correct.

Sorry

Back to the drawing board

Cheers
DD
 
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Old 10-29-2017, 08:54 AM
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Originally Posted by Undertaker


Out of desperation I decided to swap distributors over, but now the engine will not fire whatsoever.


I have followed all the necessary troubleshooting checklists, but to no avail. I have fuel, I have spark.

Please describe "I have fuel".

Are the injectors clicking and do you have 36 psi fuel pressure?

And, "I have spark". A big fat blue/white spark....or a puny yellow-ish spark?

Cheers
DD
 
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  #9  
Old 10-29-2017, 01:54 PM
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Originally Posted by Doug
Please describe "I have fuel".

Are the injectors clicking and do you have 36 psi fuel pressure?

And, "I have spark". A big fat blue/white spark....or a puny yellow-ish spark?

Cheers
DD


Thanks Doug.


I have a nice solid blue spark, and fuel pressure is okay. I cannot hear the injectors clicking. Perhaps the ECU is not earthing them?


My main concern was setting the ignition timing from scratch without removing the cam covers. Is it best to start at 6 degrees BTDC on the crankshaft pulley? Does it matter if I use #1 or #6 piston?


I figure if I absolutely have the timing correct, it eliminates a bunch of confusion.
 
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Old 10-29-2017, 05:07 PM
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Unless the pulse from the ignition coil is getting to the ECU the fuel injectors will not fire. This is the only link between ignition and fuel on the system, and often forgotten about.
 
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Old 10-29-2017, 07:39 PM
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Originally Posted by Undertaker
Thanks Doug.


I have a nice solid blue spark, and fuel pressure is okay. I cannot hear the injectors clicking. Perhaps the ECU is not earthing them?

Is the bundle of ground wires (about 5-6 of them) attached at the rear of the water rail? That's the grounding for the entire fuel injection system

My main concern was setting the ignition timing from scratch without removing the cam covers. Is it best to start at 6 degrees BTDC on the crankshaft pulley? Does it matter if I use #1 or #6 piston?
Just to get the engine running 6º BTDC would be fine. Or anywhere near that. It can be dialed-in later

#1 and #6 are a TDC compression at the same time as I recall so you could use either one. I'd use #1 to be sure, though.



I figure if I absolutely have the timing correct, it eliminates a bunch of confusion.
Basic initial ignition timing doesn't doesn't have to be spot-on just to run the engine. Firing order, though, obviously must be correct...but I think you have that covered

Cheers
DD
 
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Old 10-29-2017, 07:39 PM
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Originally Posted by Fraser Mitchell
Unless the pulse from the ignition coil is getting to the ECU the fuel injectors will not fire. This is the only link between ignition and fuel on the system, and often forgotten about.
right !

It's the white/black wire coming off the coil "-" post

Cheers
DD
 
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  #13  
Old 10-29-2017, 07:46 PM
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Thanks all, will persevere some more after work today. Cheers.
 
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Old 10-30-2017, 03:05 AM
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Doug No 1 and 6 will be at TDC at the same time but never will both be on compression
 
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Old 10-30-2017, 04:24 AM
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Originally Posted by Doug
6-2-4-1-5-3 is correct.

Cheers
DD

 
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Old 10-30-2017, 09:11 PM
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Originally Posted by o1xjr




Interesting, but confusing.


So the Haynes manual showing location of plug leads is incorrect? It has #1 lead at the 11o'clock position, (if memory serves me correct).
 
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Old 10-30-2017, 09:59 PM
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Originally Posted by Undertaker
Interesting, but confusing.


So the Haynes manual showing location of plug leads is incorrect? It has #1 lead at the 11o'clock position, (if memory serves me correct).

I can't remember where #1 is on the cap as the cars left the factory. The important things are.....

A) the distributor rotor points to the #1 position---where ever it might be.....when #1 piston is at TDC of the compression stroke and

B) the other wires follow the #1 wire in the correct sequence



Or, in your case......

I have turned the engine over by hand to TDC, on the compression stroke, on cylinder number 6 (at the front) and the rotor arm points at number two plug lead on the distributor cap. I have tried swapping the plug leads with #6 lead where the rotor points, but still zero fire.

OK, #6 cylinder at TDC of compression stroke, #6 wire installed on the cap so the rotor points to that location, and the other wires installed 2-4-1-5-3..... that should be OK

Just for the heck of it have you removed the distributor cap and cranked the engine to observe that the rotor is smoothly turning a full 360º as the engine spins? If that's OK I think you might need to look for a different problem...like why the injectors seem to be inoperative

Cheers
DD
 

Last edited by Doug; 10-30-2017 at 10:02 PM.
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Old 10-31-2017, 12:18 AM
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I have reverted back to using #1 cylinder to set up initial ignition timing. I have set it at 6 degrees BTDC on compression stroke. I cannot load the photo of my distributor, but the rotor points at 9oclock.

I will start the plug lead sequence here and see what happens. And yes, when cranking rotor turns smoothly as it should.
 
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Old 10-31-2017, 06:27 AM
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Tis one of the confusing things of the Otto Four cycle internal combustion engine. Each piston will TDC twice. But, only one is the
"power stroke". The devil is which! Many an engine has been set up 180 degrees out of phase. They pop and blow back through the intake.Not all bad. Just pull the dizzy and put it back, 180 around. Usually works.


My way is always start with #1, wherever it is. That is the static reference point for all else.


Carl
 
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