18R-GEU won't fire - no spark or injector pulse - possible igniter issue?

[Javal]

Hi Team,

I'm at that point in my build where i'm ready to start my engine (or do a test fire at least). It didn't go so well, but teething issues are to be expected.

Here's what i'm experiencing -

No spark from the coil - coil has power at all the right times, straight 12v under cranking from STA2 power wire off the ignition barrel
No injector pulse - injectors have power from the injector relay - no ground pulse from the ECU.

Now, with this in mind, the only common component in this mess is the igniter - which like the old points in the dizzy, opens the -ve side to the coil, collapses the field and gives us spark. It also uses this pulsed ground signal as the RPM signal (or 'ig') for the ECU. ECU sees the 'ig' signal and fires the injectors (this is a batch fire setup, all 4 at once).

Here's where shit gets weird - I am getting a -ve pulse from the igniter. Putting a test lamp across the terminals of the coil yields the desired results - a flashing test lamp. Yet I have no spark. It has a brand new coil, which is an off the shelf Bosch oil cooled unit to 'suit electronic ignition'.

Now to get a little more weird - the ECU is seeing the 'IG' signal - a pulsed ground / open signal. As in if you put a test lamp from B+ to the 'IG' wire on the ECU plug and crank the engine - the test lamp once again yields the desired result and flashes.

What I am thinking the issue could be

The igniter has packed up - They're old and common to go. It fits my symptoms well (no spark / injection) but the fact the coil and ECU are seeing a pulsed ground/open signal yet nothing is happening is confusing the shit out of me. The igniter body of the igniter is sufficiently grounded by the way, it has it's own dedicated ground wire to the chassis (as the bracket is powdercoated).

I've got the wrong kind of coil on there - 18RGEU's are ancient, I wonder if I should be using a standard oil type coil suitable for a points based ignition system and the fact i'm not getting proper coil field generation and collapse is why the ECU is not firing the injectors

A dead ECU in combination with one of the above. - The ECU is seeing a pulsed open / ground signal yet is not firing the injectors. This worries me.


Reference Material

18RGEU wiring diagram - simple things, aren't they? Note how the igniter is not pictured, that's because unlike later EFI Toyotas, the ECU has no control or feedback from the igniter, the igniter controls all the dwell and timing - exactly like a 21R-C setup (and 22RE????). All the ECU wants to see is the pulsed open/ground signal from the coil, effectively the 'IG' is just a tacho input to give the ECU an RPM reference.



Image courtesy of RA35GT IIRC.

Here's how my coil and igniter are wired- excuse the MS paint wiring diagram.

[RA35GT]

the ecu won't fire if there's no spark mate.

it needs to see the flyback voltage, not a ground/open circuit.

it is a little sensitive with respect to the ignition. (I had rev limit issues using a newer type ignition, but it still started)

concentrate on getting the ignition to work first.
(disconnect the ecu until you get ignition working)

[Javal]

Thanks heaps mate. Considering i'm getting a pulse to the coil but it isn't firing, i think i'm using the wrong kind of coil. I'll pick up a coil for conventional ignition and see how I fare.

[RA35GT]

What coil were/are you using?
some coils need external resistors and some don't.

(You could also check to make sure the coil isn't open circuit)

[Javal]

Coil isn't open circuit. IIRC between 1 and 2 ohms across the primaries. didn't check the secondarys. It's a brand new coil. Bosch coil to 'suit electronic ignition'. Best description I have got. Even if it's not designed to be used with a ballast resistor, it's getting straight 12V under cranking conditions and still isn't generating a spark.

Coil in question -

[Javal]

Well, I tried a conventional type coil on there (as in one to suit points ignition) - no change.

Looks like the igniter has had it, so i'm picking up another one tomorrow to wire in and we'll see how it goes from there.