no spark sob story

[notStock]

K, I've got a VT 5.0 that refuses to throw a spark. Just won't. Theres no output from the coil lead to the distributor. The car was idling happily enough, when it died. Cranked it over again and it took a long time but it caught and settled into idle again, but wouldn't take any throttle, and would bog down and die again, wouldn't take any revs.

I've replaced the ignition module with a reco unit

Put a new coil in it, mounted away on the firewall for access

After all this, theres an oddity: theres only 9-10ish volts at the coil. What's the minimum voltage needed to excite the thing?

At one suggestion I checked the injector pulse with a noid light, and that was all good, strong flashes. Is there a similar way to test the hall effect sensor for the ignition circuit? Is the distributor boned?

[dirt drifter]

i'd say u would want at least 12V at the coil, how much voltage is at the battery and ecu? u could check for dizzy pulse at the ignition module, its one of the wires in the flat plug on the front im pretty sure but i dunno which one

[VX Exec]

I had the same problem with my old N13 Pulsar matey, ran fine til one day i tried to turn her over and she ran like sh*t, as you said would bog down under revs and die... Looked at everything finally put it down to the ECU, replaced it and BAM SHE LIVES!

[notStock]

OK! No dizzy pulse! That was exactly the hint I needed...

Now, where does one get replacement dizzys for these?

[dirt drifter]

i just got one from repco for a bit under $300 but that was for a vs (non sequential injection). there are cheaper ones out there but i dunno if i'd trust them

[mr031]

yeah have seen the problem before, injection pulse put no spark, the dizzy wasnt switching to ground. had to use an oscilloscope to find that one out.

[304runner]

Yeah it could be the ECU as the Coil pulls its earth from the ECU in an on/off fashion....

[notStock]

Well, I put a new dizzy in it and it doesn't start. The only thing left is the ECU. No error codes either.

[dirt drifter]

have u got a dizzy pulse at the ignition module now? and if yes are u 100% sure that u got the leads back on right and the timing close to where it needs to be?

[notStock]

K so update. Exactly the same symptoms with new igntion train. Started look at ECU, have got 10.36v (what? sounds bad) and a toasted pin in one connector. So now my line of thinking goes bad earth/connection at some point in harness. And the blasted pin on the ecu sounds worrying too

[CHEETR]

sure its not something to do with the immobiliser? VT's are renowned for the imobiliser ring around the keyhead

[notStock]

As I understand it the immobliser cuts the injector pulse? Or am I going about it the wrong way? Noid light says ive still got injector pulse

[dirt drifter]

it costs nothing to clean the earthing points up on the motor/chassis so ya might as well do that to rule out that possibility, from memory theres the neg lead, earth strap on the passenger side front of the motor and a round terminal bolted to the rear of the passenger side head. well thats for vs i dunno for sure if a vt is the same.

does the battery have similar low voltage as the ecu power wire?

[notStock]

The chassis/engine to battery earth leads are new, 12 month old battery. It reads 12.3V with ignition on. The rear earth lead on the cylinder head is clean - I had the engine out of this car and rebuilt not too long ago, and I reconditioned the loom at the same time.

On a hunt today I looked for high resistances elsewhere... readings I got were, 12v at battery, 12v at ignition switch, with 0 resistance when turning the key. 7V at the ignition module, 8v at coil, 10v at ecu, and, at the ignition fuse, 7v and rapidly dropping, until it'd get to 0. Turn ignition off and on again and it gets up and falls again.

The dizzy was definitely in right, its about the 4th time I've done a EFI 5.0 dizzy, I just struggled getting one for a VT. It bench tested just fine too.

Got a feeling it's gonna end up being something stupidly simple...

Thanks for your suggestions too, been able to narrow it done some