S2 Still won't fire on cylinder 4

[Spacecowboyuk]

You got it. When I disconnect the king lead from the coil the spark jumps to the B+ post on the coil. When I disconnect it from the dissy cap I hear something sparking but cant see where its coming from. Might be too sunny.

Edited by Spacecowboyuk on Friday 19th July 18:27

[Spacecowboyuk]

GreenV8S said:

Let me check I got this right. You're saying you have a spark AT THE PLUG when the engine is turned over with the distributor cap is removed from the distributor?

For that to happen there's need to be a circuit from the coil to the plug. The path it would need to take is from the coil HT lead to the king lead, from the far end of the king lead to the center post on the dizzy cap, from the output post of the dizzy cap to the plug lead, from the far end of the plug lead to the plug, across the air gap in the plug to the cylinder head, from the engine to ground and back to the grounded side of the coil.

In the middle of that is a huge air gap between the center post and output post of the dizzy cap.

If you've got a strong enough spark to bridge an air gap that big you won't just see it, you'll be wearing it.

Does the spark stop when you disconnect the plug lead from the dizzy cap?

Here you go:

https://youtu.be/Gh2etFG5cqg?si=J1qEJOdBVdbz82FL

[Spacecowboyuk]

I've just refitted the original Motorcraft coil and I now have mad sparking between the king lead, the + and - on the coil itself with the cap disconnected.

Got to be the aftermarket amp, right?

Edited by Spacecowboyuk on Friday 19th July 19:11

[notaping]

It's been a while since I had a car with a dizzy, but from the vid - all the sparks are simultaneous, so it looks like your block is being charged and its discharging through all spark plugs at the same time. In effect - the exact opposite of what you want. Check your engine earth strap and check that your coil is not shorting to the block.

Might be wide of the mark, but you've got a weird one there. You need to strip it all down and build it up methodically. You'll get there. Good luck.

[Spacecowboyuk]

notaping said:

It's been a while since I had a car with a dizzy, but from the vid - all the sparks are simultaneous, so it looks like your block is being charged and its discharging through all spark plugs at the same time. In effect - the exact opposite of what you want. Check your engine earth strap and check that your coil is not shorting to the block.

Might be wide of the mark, but you've got a weird one there. You need to strip it all down and build it up methodically. You'll get there. Good luck.

Yes when the cap is off the dissy, they all seem to fire at once. When it's connected, they fire individually (except cylinder 4 of course).

Where are the earth straps on these things?

[notaping]

Haven't a clue. I'm a Cerb guy. Just look around the bottom of the block and look for a heavy cable/strap that goes from the block to the chassis. Then make sure that the connections at either end are good. They tend to corrode and although they look like they're connected - they might not be making electrical contact.

[Spacecowboyuk]

notaping said:

Haven't a clue. I'm a Cerb guy. Just look around the bottom of the block and look for a heavy cable/strap that goes from the block to the chassis. Then make sure that the connections at either end are good. They tend to corrode and although they look like they're connected - they might not be making electrical contact.

I've found at least 2:





There probably was one here too at one time.



So at least 1 from neg battery earth to chassis, 1 from chassis going into the engine/car loom. I cannot see one going from the block to the chassis though. I cannot get under enough to look for a gearbox earth. Remember though, the car does run on 5 cylinders.

Edited by Spacecowboyuk on Friday 19th July 20:22

[Spacecowboyuk]

One could have gone here too at one time to correspond with the diagonal on the other side:

[GreenV8S]

Spacecowboyuk said:

I've just refitted the original Motorcraft coil and I now have mad sparking between the king lead, the + and - on the coil itself with the cap disconnected.

Got to be the aftermarket amp, right?

Edited by Spacecowboyuk on Friday 19th July 19:11

The ones we can see do all seem to be sparking together.

You don't show the inside of the cap, but I guess if you look there later tonight you'll see the king lead sparking to all six output terminals. You must have a hell of an ignition system there - that's far further than a spark would normally travel. Typically you'd have about 25kV peak voltage at the plug, which is enough to jump about an inch. Looks like you've got around double that.

Are you getting another spark when you key off? That suggests the coil is being energised when the engine is stopped, which modern ignition systems would not uaually do.

[Spacecowboyuk]

GreenV8S said:

Spacecowboyuk said:

I've just refitted the original Motorcraft coil and I now have mad sparking between the king lead, the + and - on the coil itself with the cap disconnected.

Got to be the aftermarket amp, right?

Edited by Spacecowboyuk on Friday 19th July 19:11

You don't show the inside of the cap, but I guess if you look there later tonight you'll see the king lead sparking to all six output terminals.

Are you getting another spark when you key off? That suggests the coil is being energised when the engine is stopped, which modern ignition systems would not uaually do.

I'll show the inside of the cap tomorrow.

Yes I get spark when the key is released off. One but normally two sparks.

[Spacecowboyuk]

All ground straps have been checked. Additional strap from neg battery to engine been introduced. No change.

[lancepar]

The photo with the red wire going to ground, where is that going?

[Spacecowboyuk]

lancepar said:

The photo with the red wire going to ground, where is that going?

That's the ground which goes to the pin for the octane fuel adjustment on the plug under the dash. I've already tried to take that out of the equation with no change.

I'm now coming to the conclusion that this has something to do with the way the orirignal immobiliser was wired in. On another thread (and earlier in this one I think) I mentioned that I wasn't getting the fuel pump and injector relays to fire and I was finding positive coming down the negative earth wire. I found this out using the power probe - it showed positive. It wasn't until I then sent earth down it with the power probe that things came back to life. I then ran a earth to it and here we are but it's still masking a problem I think.

I thought Id removed everything relating to the old immobiliser but perhaps not. Does anyone have any wiring diagrams for these old systems? It's a Vecta alarm and immobiliser. Just checked the top YouTube post on my car and it says:

Edited by Spacecowboyuk on Sunday 28th July 08:09

Edited by Spacecowboyuk on Sunday 28th July 15:17

[GreenV8S]

Spacecowboyuk said:

That goes to the pins for the conversion to run the car on unleaded fuel.

The what?

[Spacecowboyuk]

GreenV8S said:

Spacecowboyuk said:

That goes to the pins for the conversion to run the car on unleaded fuel.

The what?

I meant octane adjustment at the plug.

[GreenV8S]

Spacecowboyuk said:

GreenV8S said:

Spacecowboyuk said:

That goes to the pins for the conversion to run the car on unleaded fuel.

The what?

I meant octane adjustment at the plug.

What's that?

Not being facetious - I have no idea what you're referring to. Conversion to unleaded usually means ensuring you have hardened valve seats and ethanol-friendly hoses. Adopting a lower octane rating usually means setting the static ignition timing back slightly. None of this affects the plugs or wiring.

[Spacecowboyuk]

GreenV8S said:

Spacecowboyuk said:

GreenV8S said:

Spacecowboyuk said:

That goes to the pins for the conversion to run the car on unleaded fuel.

The what?

I meant octane adjustment at the plug.

What's that?

Not being facetious - I have no idea what you're referring to. Conversion to unleaded usually means ensuring you have hardened valve seats and ethanol-friendly hoses. Adopting a lower octane rating usually means setting the static ignition timing back slightly. None of this affects the plugs or wiring.

None of this is work I've done I'm just tracking it back to threads on here and Steve Heath book. I'm on honeymoon atm so can't check back but from memory it involves grounding a certain pin on one of the plugs to adjust feed the ecu and get it to adjust for octane. Then you tweak the dissy. Nothing in that should be causing my problem so best not to dwell on it. I was simply saying to the other post what it was and that I've already disconnected it to see if it had an effect. It doesn't.

[Spacecowboyuk]

Well after taking the dash out in the hope of finding the remains of an immobiliser and failing, I think I will have to give up on this car and move her on instead. It still starts and runs with a ground introduced into the circuit but it's just not right and not firing on all 6 cylinders. So there we are. The first car I've ever given up on and I've failed to find any auto sparky to be interested enough to want to look. Very frustrating. Thanks for everyone's help on this.