Weak spark - causes?

[cat007]

Hey all

Here's the setup

EMS Stinger 4424 ECU
Ignitor from a V6 wasted spark Misti
Coils from a Supra 7M-GTE
Leads are pretty darn new - only had a few hours use.

Spark coming out of each of the plugs is - well - pathetic. Barely visible in a moderately lit garage - compared to the same plugs on my GT-T Caldina in broad daylight and the spark is very strong and visible.

Bad earth to coil bracket?

From what I understand the coils have + and - applied to them constantly - and when they are required to produce a spark, the - is taken away which is done by the ignitor, which is triggered by the ECU?

[mjrstar]

I ditched my 20+year old toyota coils on my 1g in favour of some mitsi diamante ones, and it solved my miss-fire that was happening at 18 ish psi.
They are cheap and plentiful so could be worth a shot?

[cat007]

I have thought about that. Although I have tried another set of coils (same 7M ones) and they do the same thing.
If I take a plug out and spin the dizzy by hand, the spark produced is really crap. Barely visible. Seems strange that they just decide to stop working.

Maybe a trip to pick a part is in order.

[whynot]

My thought would be the dwell time I think it is. Basically the mitsi ignitor may not be energising the coil long enough to fully magnetise it and provide a full strength spark. Any chance of trying the ignitor that came with the coil or adjusting the dwell?

[cat007]

The stock 7M ignitors are a PITA as they have some sort of built in dwell adjusting thingy - so they're awful to try and tune with.

Does anyone know what sort of dwell time the 7M-GTE coils need?

[matt dunn]

The stock 7M ignitors are a PITA as they have some sort of built in dwell adjusting thingy - so they're awful to try and tune with.

Does anyone know what sort of dwell time the 7M-GTE coils need?

Cant use Toyota igniters with aftermarket ECU's as it just doesn't work,
as you say they have dwell control built into them, and so will the ECU.

Also toyota coils are 1/2 as good as Mitsi coils.

Other than that low voltage to the coils under load,
voltage drop in the circuit somewhere
allow for the coils to draw 10 amps+ each.

Or dwell not set correctly for the coils,
but even with everything good, you may still only get weak spark with toyota coils.

What is the resistance of the coils? Should be less than 1 ohm to get good spark.

[whynot]

I have the factory ignitor on my microsquirt, it goes fine. however I do intend to change it when the new motor goes in. the dwell time set on a friends 4age is 4ms at 13 volt on a link ignitor with bosch coil. it increases at lower voltages to compensate

[rollaholic]

is it actually causing a problem though?

eye-crometer is a pretty unreliable way of measuring the strength of a spark

[cat007]

What is the resistance of the coils? Should be less than 1 ohm to get good spark.

I'll check them tonight. I'm looking around for some Mitsi coils too.

is it actually causing a problem though?

eye-crometer is a pretty unreliable way of measuring the strength of a spark

Yeah I agree - but it really is the different between viewing a tiny spark made by a 9 volt battery, and a power line. The spark produced on other car's really is a decent spark, but the spark produced by mine is pathetic. The comparison is much like this video:

http://www.youtube.com/watch?v=eNx9YDodgE0

Except mine is way worse than what he calls a bad spark. It seems to even have trouble jumping the gap across the plug (set to 0.8mm).

[cat007]

So after faffing around for god knows how long I have found what was causing my weak spark.

I hadn't connected the earth to the ignitor. It was taped up inside my loom (from when I wired in my LC1 wideband)

OMG I feel like a fool.

as you were

Hunt

[cat007]

New plugs (6 heat range instead of the 7's I normally use - as they were out of stock) and all is well.
Revs up fine. Starts fine. YAY

[rollaholic]

sounds like the kind of thing i would do!

always nice to work it out though eh.