Ignition Cut

[mrjezza]

Hey everyone,

Finally got my car back (don't ask) and while getting it washed at a car wash cafe I picked up a drifting magazine they had to read while you get your car washed.  I saw a review of a Bee*R Rev Limitter (sic) that worked by cutting ignition instead of cutting fuel... apparently this would be a less drastic cut and would leave the car on boost, etc.  However, an interesting side-effect was that as fuel was still being supplied, a flame would shoot out the exhaust.

Seemed like a nifty little unit, had 2 rev limits, 1 to be used as the high limit, one to be dialed in as a launch control type limiter for drag racing, toggled by a switch.

Now for the question: Is there a way to cut all ignition with 1 wire or will I have to interrupt all 4 wires running out of the ECU?  If so, what pin on the ECU connector is it?  I've looked at the wiring diagram and can't work it out.

I'm keen to make myself an ignition cut-off switch regardless.  I've always wanted to shoot flames at tailgaters... I didn't realise it was this easy.

[Gunni]

one real easy way would be to cut the power to the ecu, surtenly kills the spark then. what you need to be cutting is the 12v wire to the coils

[mrjezza]

My main concern was whether there was an easier way to do it than to individually interrupt the signal along each of the 4 wires to the coils.  If there was a way to cut the entire ignition process with 1 wire it would be easier because I could use a simple single pole switch from an electronics store.

Otherwise I'm not too sure how I would wire it up to cut 4 wires with 1 button; maybe using 4x relays and a master switch?

Edit (to make things clearer and correct my own stupidity):

Basically, I can see that interrupting the wires connected to ecu on pins 24, 25, 51 & 52 will interrupt the ignition signal to coils for cyls 3, 1, 4 and 2 respectively, thus cutting ignition.  Can anyone suggest an easier way that involves only 1 wire?

[johna]

Instead of switching the positive voltage, switch the negative. All four coils share a common ground. According to the ETM they all meet up at S108 (splice) which is somewhere in the engine bay.

There is a company here in Australia who make some electronic kits which may be of interest to you:

Rev Limiter / Gear Shift Indicator Kit
Engine Immobiliser MKII Kit

When you combine these two electronic kits together you have a shift light plus it will cut the ignition at a pre-set rev limit. I had the shift light only installed in my car.

Once word of warning though. I have heard that if you disconnect a coil when the ignition is on you can damage the ECU. Check with an expert to see if doing this could cause any damage.

[mrjezza]

Thanks John, I had actually had a look at the jaycar kit when I saw it on your website (I really liked what you did with yours with the 3 lights at the top of the dash and will probably do that myself soon

When you say disconnecting the coil may damage ECU, do you mean disconnecting power to the coils or interrupting the trigger signal from the ECU?

I'm not willing to risk damage to the ECU so if you mean power to the coils thats out of the equation.  On the other hand I can see how the trigger signal might be safe to interrupt... My logic is that I'd be like a piggy back ECU (that only cuts ignition to make flames haha)

[mrjezza]

I wired up a relay with a trigger button that successfully cut the ignition to 1 cylinder, but after a bit more research apparently interrupting the ignition will lead to fuel damaging piston rings and contaminating your oil.

I'm going to abandon this.  I love my engine more than I love flames.

[johna]

I think you have made the right decision not to mess with it. However, if you still want flames maybe try http://www.flamethrowers.com.au/.