Really stumped. 5B? misfire after replacing the following.
Initially 5B injector wasn't clicking but after rechecking injector harness main connector, it came to life.
Injector fuel hose.
Spark plugs and boots.
Injector filters and seals
Flow tested and cleaned injectors.
All injector plugs and injector wiring boots.
I completely removed the injector harness to do this.
I have done the following.
Checked all injectors are clicking.
Disconnected 5B injector, no change. Disconnected each injector on bank B and engine slows.
Checked 5B compression good.
Checked 5B spark with inline indicator.
Removed B injector rail and applied 12v to each injector to observe fuel was spraying.

So air, fuel, compression and spark is all go.

I've missed something but I'm out of ideas.

I would appreciate any suggestions.
Thanks in advance.

 

Did you move the injector to another cylinder to test it that way? If the problem follows to another cylinder then its the injector. If it stays then maybe check the distributor? If the spark plugs and the boot (i assume whole spark plug wire) were changed then thats where i would check next. Not an expert though. No direct experience on this car.
EDIT: maybe its worth ringing out the injector harness too.

 

Elm,

2 things that may be happening:

- You've confirmed spark to the plug. But you don't seem to have confirmed spark at the plug electrode. So maybe pull the plug and test it against the block with the engine running

- You've confirmed compression but that will be with a tester in the spark plug hole. Perhaps you don't have compression when the plug is inserted? Maybe try spraying around the plug hole when the engine is running to confirm no leak?

Good luck

Paul

 

Thanks MooseOHJ. Injector swap is not easy as I used ferrule not clamps.
Not the plug wires as they are relatively new.
The injector harness is where I will go next.

 

Thanks Paul.
I placed the tester between the top of the plug and the wire and I have since replaced the plug with a new one to eliminate that possibility.
New plug seated well and used anti seize. No indication of leak in this area.

 

MMMMM

What year is this beast?

You mention removing B Bank rail, so maybe its a late V12, or a 6ltr.

Your profile has a 1971 XJ6, oops, missing some cylinders there.

Depending on year, Marelli or Lucas Ignition System.

 

Hi Grant.
It's an '89 V12.
Will update the profile.
The Mk1 XJ6 has gone back to Melbourne.
It's a Marelli Ignition I am told and also informed the '89 was the year of change over for stuff so a bit of a mish mash.
Because the fuel hoses are new, I was able to undo the clamp plates on the B side and lift that rail side and hose injectors clear of the head to watch the fuel stream as I applied 12 volts to each injector.
Today I checked the harness end to end from the male main connector to each injector and all tested well.
I also put a grounded spark plug on the #5 lead to test spark at the plug as Paul suggested. All good.
Even though I have tested it to be only #5 faulty, I'm pulling the distributor cap and leads next to double check correct connection.
Running out of ideas but the next test will be to scope the actual signal at the injector. I don't have an oscilloscope though so will have to source that.
Thanks for your input.

 

Goodo.

14 HT leads = Marelli.

A one cylinder out and the Injector is Injecting, means the spark inside the comb chamber is not happening, and that has been common to me over many years and not just Jags. The Comp pressure makes the "jump" harder, so the coil really has to ***** up and do its thing.

High resistance in leads, especially the V12 is #1, and 5 years is the average life. I run Magnecor, NOT cheap, but 10 years usual life.

I always run NGK BPR6EF sparkers, the "P" is projected nose spec, and puts the spark IN the bang juice, as apposed to BR6EF, which has the spark almost up inside the cone.
NO they will NOT hit the pistons, too far away, in doubt???, take the head off and measure it, hahaha.

Marelli has cap and rotor issues on a good day. so that is a good thing to sort. It is usually dropping a whole bank., not 1 cylinder.

EFI looms are now as common as cold beer for causing issues,. and its purely age related and location.

Have fun.

 

Today Swapped 5B ignition lead with a known good lead from A side. No change.
I then removed the distributor cap, cleaned it, and re routed all the plug leads. No change.
Checked and installed another new plug gap at 25th. No change.
I retested 5B compression. 200 PSI.
Tried the Italian tune up. No improvement.
Clearly it is either not getting fuel or spark as it has air and compression.

This is so frustrating. I drove the car 900km from Melbourne to Sydney after I bought it and have since driven it weekly without a problem. Drove like a dream.
I have now dismantled the injection and ignition system and removed the pedestal so many times I can do it blindfold, and I don't mind doing it.

Don't feel obliged to respond. At this point I have resigned to failure until I can think of something else.
I'll probable run a new twopair from the main connector to the injector before I replace parts.
I don't want to be a parts cannon but may have to install a new injector. In the meantime I will gather my emotional strength.
Too bad, as there is a big car rally I have pre-booked for this Saturday.

 

Bugga.

Ita looking more like an Injector?

The Injectors are fired in 4 batches of 2, in case you did not know that.

1,3,5A
2,4,6A
1,3,5B
2,4,6B

This helps with loom issues mostly. The pigtails to the Injectors can crack up,

Something I did with one of my PreHE beasts with issues (many), was to detach the EFI loom from the base of the V, running engine, I moved that loom around, Doug calls it "the fiddle factor", and I got 12 working, the some dropped out, then 12 again, then it died, oops. The loom looked good, and was crispy crackly, but sad enough to upset the thing.

So made my own and moved on.

 

Maybe swap the 2 ignition coils, then the 2 ignition amps to see if issue moves/changes?

 

Another thought.

Look up inside the actual Injector loom plug. Make sure the 2 female terminals ends are actually there.

Very common issue on the CTS for them to push back as the plug is plugged, same Injector style arrangement.

 

Yes Grant. Have had that happen, but ok in this situation.
New pig tails and terminals. I have photos and a video I hope to post soon.
I found the Electrical schematic and did see what you mention, hence only 6 pins at the main injector harness, and I was able to identify the wire colors for each.
Today I applied 12v pulse direct to the injector terminals with the motor running. No improvement.
Even though I had fuel from the injector last time I tested it external to the manifold, it would seem, even though the injector continues to click, there is now no flow.
Also the plug is not wet and there is no discoloration, so no combustion..
Tomorrow I will remove the fuel rail again to begin the rectification.
Thank you all for your input. I will keep you posted.

 

Spot on Grant.
I removed the injector and put it back on my test rig.
At idle, there was a hesitation at the start then an odd flow pattern.
No leak at the pressure test.
So I bought a new injector, installed it and now all is well.
Thank you all so much for your input and especially Grant.

 

Well done.

Simple cars these V12's.