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Old 08-11-2010, 05:41 PM   #1
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Default Ignitor question

Have just been fitting my emerald ECU, was once fitted to a MX5 so sort of a plug and play harness, when trying to start the car I had no spark, I traced the wires an found the signal is coming from the ECU to the ignitor but not going any further, the black and wire seems to go no where in the harness so guessing that is the issue. I can bypass the ignitor and have the ECU fire the coils direct, but wondering if there is a reason to keep the ignitor?

I know the tacho is driven by the ignitor, I can connect the tacho wire from the ECU to drive that though.

Paul
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Old 08-11-2010, 05:50 PM   #2
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In theory, the black/white wire can be pulled up to +12 with a 1k resistor. Some folks claim that the ignitor won't work without this. I can't imagine why, but you can try it.

On the output side, the ignitor isn't providing a voltage, but rather a closure to ground. You should have +12 coming INTO the ignitor from the coils (white and red, assuming a '90-'93 car) and then the ignitor provides the closure to ground to complete the circuit.

I'm not at all familiar with the emerald, but from their webpage it claims to have three onboard ignition drivers. If these are in fact capable of sinking several amps of current, then yes, you could drive the coils directly. A stock ECU would not be capable of this.
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Old 08-12-2010, 05:30 AM   #3
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I will email Emerald and see what they say, if its a no go will be down to the shops for a 1k resistor.
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Old 08-12-2010, 07:16 AM   #4
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I got a very quick reply from Emerald, the ECU has internal high power amplifiers that are designed to control the coils directly. So should be fine to drive the coils, means I can get rid of the ignitor as well so one less thing to go wrong on the car.
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Old 08-12-2010, 11:59 AM   #5
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Sounds like a plan. I'd advise running new leads from the ignition coils to the ECU (14 - 16 awg or 1.3 - 1.6mm dia should suffice). The brown and brown/yellow leads which run from the stock ECU to the ignitor are quite thin, as they were not intended to carry much current. If it's easier, you can splice into the red and white leads at the location of the igniter connector, rather than running all the way up to the coils.
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