Systems that get rid of optispark, one question!
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Systems that get rid of optispark, one question!
Ok so I've seen some systems that completely get rid of the optispark, one question, how is the fuel controled after the optispark is removed?
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Joined: Feb 2002
Posts: 345
From: CA
Doesn't the opti have a crank positioning sensor which would indicate to the system when to fire an injector? I think the LTCC requires the use of the opti for this purpose but the spark distribution is controlled by the LTCC.
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From: Hell was full so they sent me to NJ
The low resolution pulse from the Opti is essentially a cam position sensor. And that signal has to be present for the stock LT1 PCM to control the fuel system. Since injection is sequential, it has to know where the cam is, because you can't know when to fire the injectors from crank position alone. If the PCM can not find the low resolution pulse for 720 pulses from the high resolution sensor, it shuts down the fuel pump and the injectors.... no start, DTC 16.
To completely get rid of the Opti, you would need the following:
1. an aftermarket engine management computer that could function with a crank position signal only, and run in batch fire injection mode.
2. an aftermarket computer that could function with a crank sensor and a home-brew cam position sensor, and the add-on 8-channel ignition driver required for 8 LS1 coils... examples of this would be the FAST/eDIS system, or the MoTeC/IEX setups. You are talking big $$$.
3. Find one of the 20 or so Electromotive Opti-Eliminator/SDI units that were made. I ran my engine without the Opti for 2 years with one of these. They are "flawed" in that they rely on a crank trigger, and the injectors can synch 180deg out of phase.
4. Get an MSD "CPC" cam drive stub, and mount it in the back of the LT1 intake manifold. Build a convertor to convert the CPC cam position output signal to the equivalent of the Opti low res pulse. Use this to feed the stock PCM...... I really think this would be the easiest way to go.
In 1 and 2 above, you would not be able to use the stock PCM any more, to control the fuel pump. I suspect the VSS would still work, so you could keep the speedo.
Hmmmmmm.... closing in on 10,000 posts.... I bet 1,000 of them have been about the Opti, and alternatives thereto
To completely get rid of the Opti, you would need the following:
1. an aftermarket engine management computer that could function with a crank position signal only, and run in batch fire injection mode.
2. an aftermarket computer that could function with a crank sensor and a home-brew cam position sensor, and the add-on 8-channel ignition driver required for 8 LS1 coils... examples of this would be the FAST/eDIS system, or the MoTeC/IEX setups. You are talking big $$$.
3. Find one of the 20 or so Electromotive Opti-Eliminator/SDI units that were made. I ran my engine without the Opti for 2 years with one of these. They are "flawed" in that they rely on a crank trigger, and the injectors can synch 180deg out of phase.
4. Get an MSD "CPC" cam drive stub, and mount it in the back of the LT1 intake manifold. Build a convertor to convert the CPC cam position output signal to the equivalent of the Opti low res pulse. Use this to feed the stock PCM...... I really think this would be the easiest way to go.
In 1 and 2 above, you would not be able to use the stock PCM any more, to control the fuel pump. I suspect the VSS would still work, so you could keep the speedo.
Hmmmmmm.... closing in on 10,000 posts.... I bet 1,000 of them have been about the Opti, and alternatives thereto
Last edited by Injuneer; May 9, 2003 at 07:28 PM.
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