Build Thread: '99 C2 996 LS1 Swap
08-14-2024 | 12:07 PM
#406
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From: Newport Beach
I am about to undertake making a harness for my 2001 carrera 4 and plan to use the Holley Terminator Maxx. Did you ever figure out how to get the AC control to work with the snowflake switch? I have spent days browsing forums, and there seems to be several way to send the coolant temp, oil pressure, and tach back to the DME but I would like to do this once and not butcher the stock Porsche harness several times. Do you have any guidance on what’s needed to merge the Holley harness and stock harness?
It seems the cpe harness uses the revcan2 module to handle the AC request for the GM Ecu, but at $400, I believe the Holley should be able to control this without the extra expense. The PWM signal from the snowflake seems to be an issue in the factory DME to work with the swap. Thank you.
It seems the cpe harness uses the revcan2 module to handle the AC request for the GM Ecu, but at $400, I believe the Holley should be able to control this without the extra expense. The PWM signal from the snowflake seems to be an issue in the factory DME to work with the swap. Thank you.
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gtxracer (08-21-2024)
10-14-2024 | 01:46 AM
#407
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Do you recall if the DME was looking for a signal from one of those sensors you mentioned in order to trigger the AC kick on? I have a separate circuit for the AC through the terminator right now. The snowflake signal has been intermittent from the HVAC controls. I think the crank sensor is the key, and I did tie this into the Porsche harness. Do you remember which pin you teed into for crank signal?
10-16-2024 | 10:07 PM
#408
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@gtxracer , sorry to crash your thread, but I would love to just have a few mins of your time to pick your brain on a Holley+LS swap I am currently doing. I've been combing your and other threads religiously, but still have burning questions. For some reason, I can't DM - might be a new acct thing...? If that's possible, you'd make my day.
10-16-2024 | 10:13 PM
#409
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Joined: Oct 2024
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I am about to undertake making a harness for my 2001 carrera 4 and plan to use the Holley Terminator Maxx. Did you ever figure out how to get the AC control to work with the snowflake switch? I have spent days browsing forums, and there seems to be several way to send the coolant temp, oil pressure, and tach back to the DME but I would like to do this once and not butcher the stock Porsche harness several times. Do you have any guidance on what’s needed to merge the Holley harness and stock harness?
It seems the cpe harness uses the revcan2 module to handle the AC request for the GM Ecu, but at $400, I believe the Holley should be able to control this without the extra expense. The PWM signal from the snowflake seems to be an issue in the factory DME to work with the swap. Thank you.
It seems the cpe harness uses the revcan2 module to handle the AC request for the GM Ecu, but at $400, I believe the Holley should be able to control this without the extra expense. The PWM signal from the snowflake seems to be an issue in the factory DME to work with the swap. Thank you.
Last edited by av00va; 10-16-2024 at 10:15 PM.
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gtxracer (10-16-2024)
10-16-2024 | 11:11 PM
#411
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@gtxracer , sorry to crash your thread, but I would love to just have a few mins of your time to pick your brain on a Holley+LS swap I am currently doing. I've been combing your and other threads religiously, but still have burning questions. For some reason, I can't DM - might be a new acct thing...? If that's possible, you'd make my day.
I’ll send you a PM so we can start chatting!
10-18-2024 | 05:50 PM
#413
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I'd recommend using a 58x LS computer and DBW throttle body. Buy a Kennedy adapter and Stage 2 clutch. Use a create LS3 if you can afford it, otherwise find a 58x aluminum block engine and choose between GM and Holley TermX computer. Each have their own pros/cons. If you have a 996.1, you don't need a new wiring harness, just put the Porsche sensors (oil pressure, coolant temp) into the LS engine and keep the LS sensors too. Wire the 58x tach wire directly to Porsche tach signal wire and tach will work. The rest is pretty easy. You can thin out the original harness if you want to but not necessary.
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zbomb (10-18-2024)
10-18-2024 | 06:07 PM
#414
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From: Massachusetts
FWIW - from my experience battling DBW issues with the easy to mount C7 pedal and E38, AND not being able to get WOT with the E38 and Porsche pedal, I would save the headache and go standalone without dumping effort into the GM ECU.
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gtxracer (10-18-2024)
10-18-2024 | 07:03 PM
#415
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I'd recommend using a 58x LS computer and DBW throttle body. Buy a Kennedy adapter and Stage 2 clutch. Use a create LS3 if you can afford it, otherwise find a 58x aluminum block engine and choose between GM and Holley TermX computer. Each have their own pros/cons. If you have a 996.1, you don't need a new wiring harness, just put the Porsche sensors (oil pressure, coolant temp) into the LS engine and keep the LS sensors too. Wire the 58x tach wire directly to Porsche tach signal wire and tach will work. The rest is pretty easy. You can thin out the original harness if you want to but not necessary.
10-18-2024 | 07:09 PM
#416
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Thanks. Good info. At the moment I am just trying to track down the trigger of fuel pump relay wire off the ecu. I know it is pin number 63 but do not know the color. I think the tach wire is in the engine bay and is purple with green tracer. But i am not sure. I have a 99 as well so if you know the colors that would help me a lot. Thanks
I used the tach signal wire at the DME. It's only 1 wire, I can't recall the color but it matched the DME 996.1 pinout, I believe pin 78. Check here.