Porsche 997 C4S LS Swap
06-18-2017, 12:50 PM
#141
Been awhile since my last update and everything is starting to come together as planned with the electrical. Did have a setback with the pedal and TAC module, I was trying to use a truck pedal and TAC which don't play well together with my PSI harness and PCM so ended up having to buy a C5 pedal (which fits better) and C5 TAC module. After figuring that out my LS2 throttle body responds and no more PCM errors.
Majority of all the gauges are working and car turns overs and builds oil pressure but I have not put fuel or spark to the engine till I get my coolant vacuum filler (ordered). Fuel pump is definitely working and took me 10sec to realize it was spraying out the back before I pulled the relay.
Rear sway bar has also been dropped, can't remember who's build used aluminum plates buts since I had pieces left from my engine mounts I did it in a similar way but only lowered about an inch and drilled a 2nd mounting hole in the control arm for strength. Overall was pretty easy and took less than 30min to fabricate and mount up.
Also been spending time getting other features of the car back together like the Navigation, A/C controller and center console.
Next weekend plan is to start this beast up. Wish me luck..
Majority of all the gauges are working and car turns overs and builds oil pressure but I have not put fuel or spark to the engine till I get my coolant vacuum filler (ordered). Fuel pump is definitely working and took me 10sec to realize it was spraying out the back before I pulled the relay.
Rear sway bar has also been dropped, can't remember who's build used aluminum plates buts since I had pieces left from my engine mounts I did it in a similar way but only lowered about an inch and drilled a 2nd mounting hole in the control arm for strength. Overall was pretty easy and took less than 30min to fabricate and mount up.
Also been spending time getting other features of the car back together like the Navigation, A/C controller and center console.
Next weekend plan is to start this beast up. Wish me luck..
06-18-2017, 04:15 PM
#143
Staging Lane
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interesting...does the 997 engine sit lower than the 996? My Transmission to LS3 adapter plate is about 1-2" higher than yours. My sway bar only had a 0.1" interference. I like your simple solution...those are often the best!
06-18-2017, 05:58 PM
#144
Eric at A&E made my adapter so could be a little difference in shape or how the AWD 997 trans sets further back. I also fabricated my engine mounts for the engine to sit up pretty high in the engine compartment.
BTW, which wire of your DME did you tap into for the Tach?was it the engine speed sensor white/white?
BTW, which wire of your DME did you tap into for the Tach?was it the engine speed sensor white/white?
06-18-2017, 09:04 PM
#145
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Also, once I had an operational tach, my dash lit up with 4x the errors...i think the Porsche ECU it need a lot of the issues until it knows the engine is running.
Good luck with engine start, super exciting!!
06-19-2017, 01:10 PM
#146
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I just hooked the GM tach signal wire off the PCM to the Porsche Tach wire at he DME. It looks to be working well.
Eric at A&E made my adapter so could be a little difference in shape or how the AWD 997 trans sets further back. I also fabricated my engine mounts for the engine to sit up pretty high in the engine compartment.
BTW, which wire of your DME did you tap into for the Tach?was it the engine speed sensor white/white?
BTW, which wire of your DME did you tap into for the Tach?was it the engine speed sensor white/white?
06-22-2017, 11:17 AM
#149
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06-25-2017, 02:01 PM
#150
It's alive... turned over and started 1st try. Love the sound of the open headers but not able to rev it up till I get the exhaust done.
Couple things I ran into that I need to get sorted out.
- Vacuum bleeder I purchased from Fleabay is a total POS. Threads binding, leaks and unable to hold a vacuum.
- ignition on wire I selected for the LS PCM has. A delayed power off so engine runs 20-30sec before turning off. Ned to probe around and find a new source.
- Fuel pump relay I changed from having +12v straight to the GM PCM to just sending the negative signal to engage the Porsche relay. For whatever reason my original configuration was not working well and was cutting out.
- White tach wire not responding. I do have a 24x setup and know I will need a Dakota Digital signal converter to output 58x but was thinking I would at least get some movement of the tach gauge by hooking it up.
- Fan on circuits. Still need to research and look deeper into Motronic 7.8 and the fan relay unit in the passenger fender.
Couple things I ran into that I need to get sorted out.
- Vacuum bleeder I purchased from Fleabay is a total POS. Threads binding, leaks and unable to hold a vacuum.
- ignition on wire I selected for the LS PCM has. A delayed power off so engine runs 20-30sec before turning off. Ned to probe around and find a new source.
- Fuel pump relay I changed from having +12v straight to the GM PCM to just sending the negative signal to engage the Porsche relay. For whatever reason my original configuration was not working well and was cutting out.
- White tach wire not responding. I do have a 24x setup and know I will need a Dakota Digital signal converter to output 58x but was thinking I would at least get some movement of the tach gauge by hooking it up.
- Fan on circuits. Still need to research and look deeper into Motronic 7.8 and the fan relay unit in the passenger fender.
06-25-2017, 06:49 PM
#151
Ok so had more time to think about the exhaust setup and I keep going back to the idea of a turbo bumper and happen to find one local that I could pick on the cheap but uncertain if I will have enough space to tuck a MF x-flow muffler under the bumper similar to First350's setup. MF muffler is 20" in length which will fit but Ned to consider where the cutouts on the turbo bumper for the quad tips.
Other idea rattling around my brain is a GT3 bumper with center quads but impossible finding one on the cheap.. maybe a Duraflex knockoff but have seen a lot of negative reviews on fitment and quality.
Think I need to pull out my C4S bumper from storage and measure up the fitment and space before considering purchasing the 997TT bumper.
Other idea rattling around my brain is a GT3 bumper with center quads but impossible finding one on the cheap.. maybe a Duraflex knockoff but have seen a lot of negative reviews on fitment and quality.
Think I need to pull out my C4S bumper from storage and measure up the fitment and space before considering purchasing the 997TT bumper.
06-27-2017, 06:40 PM
#152
Decided to get the 997 turbo bumper before moving onto the exhaust and good thing I did, there is less than 4" gap between the crank pulley and bumper so don't think I will be stuffing any muffler underneath there. Maybe an x-pipe will fit with the quad tips but I will leave that up to Profab in a couple months.
06-28-2017, 07:23 PM
#155
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It's alive... turned over and started 1st try. Love the sound of the open headers but not able to rev it up till I get the exhaust done.
...
- ignition on wire I selected for the LS PCM has. A delayed power off so engine runs 20-30sec before turning off. Ned to probe around and find a new source.
- White tach wire not responding. I do have a 24x setup and know I will need a Dakota Digital signal converter to output 58x but was thinking I would at least get some movement of the tach gauge by hooking it up.
- Fan on circuits. Still need to research and look deeper into Motronic 7.8 and the fan relay unit in the passenger fender.
...
- ignition on wire I selected for the LS PCM has. A delayed power off so engine runs 20-30sec before turning off. Ned to probe around and find a new source.
- White tach wire not responding. I do have a 24x setup and know I will need a Dakota Digital signal converter to output 58x but was thinking I would at least get some movement of the tach gauge by hooking it up.
- Fan on circuits. Still need to research and look deeper into Motronic 7.8 and the fan relay unit in the passenger fender.
Ignition: I had the same issue...I had run it via the O2 sensor heater, which stayed on for ~20 seconds after the ignition was off. I finally tapped into the ignition wire directly at the key switch
RPM: The 1st white wire I choose ended up being wrong...IIRC there were 2 identical white wires in the Porsche wiring loom (engine bay)
Fan: The 996 cooling fans are triggered off a ground...I swapped my LS3 relay circuit to a ground so that my LS3 ECU was turning on the fans. Since the LS3 does not have 2 Cooling fan relays( hi/low), I just tied the 996 Hi/low together so my fan only have a Off/High setting. your 997 may be different, but if you want more details let me know and I can take a picture of the RH instructions.
08-07-2017, 08:19 PM
#159
Looks like Photobucket is back up so here's a quick update..
- Ignition issue solved by tapping into ground source instead of +12v
- Cooling fan relay ended up running +12v power wire to relay module behind passenger headlight
- Tach signal I picked up a Dakota digital but not wired in yet
Damaged rocker panel has been cutout and sized up with replacement piece, still need a door and to pull lower hinge out about 1/2" so guess I will start searching local yards and Fleabay for the door.
Slow progress due to travel and Florida heat but hopefully won't be doing as much travel over the next month or so.
- Ignition issue solved by tapping into ground source instead of +12v
- Cooling fan relay ended up running +12v power wire to relay module behind passenger headlight
- Tach signal I picked up a Dakota digital but not wired in yet
Damaged rocker panel has been cutout and sized up with replacement piece, still need a door and to pull lower hinge out about 1/2" so guess I will start searching local yards and Fleabay for the door.
Slow progress due to travel and Florida heat but hopefully won't be doing as much travel over the next month or so.
