What to do with computer on a carburetor build?
02-23-2015, 10:33 PM
#1
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What to do with computer on a carburetor build? I'm not sure what to do with my computer and wires for my build. If anyone can help me it would be greatly appreciated. My goal is to hide or delete everything that I can, but I do not know what to keep and what I can do without. I also would like to know how people get away with passing inspection with a carburetor setup. I'm working with is a 98 Trans Am, I have a LS9 block that I'm building a 416 stoker with a carburetor setup.
Thanks in advance!!!!
Thanks in advance!!!!
02-23-2015, 11:59 PM
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Lol, I know someone who will pass me as long as it does not throw any codes, but I don't know how much he can let me get away with. I read all over the place about people with carbureted set ups driving on the streets, but never anything about how they get away with it.
02-24-2015, 03:47 AM
#5
Leave the PCM in place and have it tuned to not report any DTC. Haven't tried with a 98 but most LS1 PCMs can be tuned to pass the emission and readiness tests.
If they do visual inspections then you will fail
If they do visual inspections then you will fail
02-24-2015, 07:15 AM
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So what do most people do with all of the wires and connectors for fuel injectors and sensors? Hide them in the firewall? I should be fine inspection wise as long as the computer will pass. Just trying to figure out how to clean everything up mostly. Where to hide the wires and such.
Last edited by 98 MECHAM TA; 02-24-2015 at 07:35 AM.
02-24-2015, 10:19 AM
#7
So what do most people do with all of the wires and connectors for fuel injectors and sensors? Hide them in the firewall? I should be fine inspection wise as long as the computer will pass. Just trying to figure out how to clean everything up mostly. Where to hide the wires and such.
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02-24-2015, 12:08 PM
#8
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Most people don't put a carbureted motor in and try to pass inspection. The few carbureted 4th gens I have seen all have been race cars. The way the engine harness is laid out its going to be hard to make it look good IMO. The cleanest way would be to remove all the wiring and computer.
02-24-2015, 08:33 PM
#9
You can completely remove all the engine harness including the PCM, then make a standalone harness with only the basic wiring so the PCM will talk to the OBD2 port and report everything is good.
This way you can tuck the PCM under the dash and clean the engine compartment.
However, to have gauges you need to keep the PCM alive and hooked to all sensors you want to have a reading. Do it as follows:
1- Coolant temp, oil pressure and volts are hooked directly to the cluster, you need to provide the signal to it making a standalone harness from the engine to the cluster.
2- Fuel gauge, Tach and speedo get the signal from the PCM. You need to keep the Vss sensor and fuel sender hooked to the PCM. The Tach signal will be tricky because it comes from the Crank sensor but a LS9 has a 58x signal. A 98 PCM can't read it so you will need an external Tach hooked to the MSD module.
3- Lights, windows and all other accesories will work if you keep the BCM.
Honestly I don't see the need of going to a carburetor. A good setup and tune will give you the same power a card does but with all the advantages of EFI
This way you can tuck the PCM under the dash and clean the engine compartment.
However, to have gauges you need to keep the PCM alive and hooked to all sensors you want to have a reading. Do it as follows:
1- Coolant temp, oil pressure and volts are hooked directly to the cluster, you need to provide the signal to it making a standalone harness from the engine to the cluster.
2- Fuel gauge, Tach and speedo get the signal from the PCM. You need to keep the Vss sensor and fuel sender hooked to the PCM. The Tach signal will be tricky because it comes from the Crank sensor but a LS9 has a 58x signal. A 98 PCM can't read it so you will need an external Tach hooked to the MSD module.
3- Lights, windows and all other accesories will work if you keep the BCM.
Honestly I don't see the need of going to a carburetor. A good setup and tune will give you the same power a card does but with all the advantages of EFI
Last edited by MontecarloDrag; 02-24-2015 at 08:38 PM.
02-24-2015, 09:47 PM
#10
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You can completely remove all the engine harness including the PCM, then make a standalone harness with only the basic wiring so the PCM will talk to the OBD2 port and report everything is good.
This way you can tuck the PCM under the dash and clean the engine compartment.
However, to have gauges you need to keep the PCM alive and hooked to all sensors you want to have a reading. Do it as follows:
1- Coolant temp, oil pressure and volts are hooked directly to the cluster, you need to provide the signal to it making a standalone harness from the engine to the cluster.
2- Fuel gauge, Tach and speedo get the signal from the PCM. You need to keep the Vss sensor and fuel sender hooked to the PCM. The Tach signal will be tricky because it comes from the Crank sensor but a LS9 has a 58x signal. A 98 PCM can't read it so you will need an external Tach hooked to the MSD module.
3- Lights, windows and all other accesories will work if you keep the BCM.
Honestly I don't see the need of going to a carburetor. A good setup and tune will give you the same power a card does but with all the advantages of EFI
This way you can tuck the PCM under the dash and clean the engine compartment.
However, to have gauges you need to keep the PCM alive and hooked to all sensors you want to have a reading. Do it as follows:
1- Coolant temp, oil pressure and volts are hooked directly to the cluster, you need to provide the signal to it making a standalone harness from the engine to the cluster.
2- Fuel gauge, Tach and speedo get the signal from the PCM. You need to keep the Vss sensor and fuel sender hooked to the PCM. The Tach signal will be tricky because it comes from the Crank sensor but a LS9 has a 58x signal. A 98 PCM can't read it so you will need an external Tach hooked to the MSD module.
3- Lights, windows and all other accesories will work if you keep the BCM.
Honestly I don't see the need of going to a carburetor. A good setup and tune will give you the same power a card does but with all the advantages of EFI
02-24-2015, 10:57 PM
#11
Even for a carbed LS9 you need the crank reluctor and sensor to feed the signal to the ignition system. The cam sensor is also needed.
Since there is no distributor, the ignition has to be triggered by something. That trigger is the crank sensor.
The easiest and cheapest way is to use a MSD timing controller, it needs the crank and cam sensors feed, it plugs to the coils and you can program the timing curve using the software.
The other way is to use an external crank trigger wheel but they are more expensive
Since there is no distributor, the ignition has to be triggered by something. That trigger is the crank sensor.
The easiest and cheapest way is to use a MSD timing controller, it needs the crank and cam sensors feed, it plugs to the coils and you can program the timing curve using the software.
The other way is to use an external crank trigger wheel but they are more expensive
02-24-2015, 11:34 PM
#12
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Even for a carbed LS9 you need the crank reluctor and sensor to feed the signal to the ignition system. The cam sensor is also needed.
Since there is no distributor, the ignition has to be triggered by something. That trigger is the crank sensor.
The easiest and cheapest way is to use a MSD timing controller, it needs the crank and cam sensors feed, it plugs to the coils and you can program the timing curve using the software.
The other way is to use an external crank trigger wheel but they are more expensive
Since there is no distributor, the ignition has to be triggered by something. That trigger is the crank sensor.
The easiest and cheapest way is to use a MSD timing controller, it needs the crank and cam sensors feed, it plugs to the coils and you can program the timing curve using the software.
The other way is to use an external crank trigger wheel but they are more expensive
02-25-2015, 06:31 AM
#13
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Okay, I guess I need to get with him more on this. I looked up the regulations on the daytona prototype. It does use an ecu. Its just the way he is describing the build to me is confusing me a little lol. I'm just wanting to get a head start on my engine bay with everything out. I'll just wait till I get along further so that I know exactly what is needed. Best not to jump the gun right? Thanks for the help it cleared up alot of questions for me.