4th GEN FBODY LS2 SWAP
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4th GEN FBODY LS2 SWAP I've got a 99 Trans am. Ls1 had nos run on it as some point and has a spun main bearing. I've got an LS2 sitting around out of a GTO. All GTO LS2s are a 24x so should be good to go there right? How do I deal with everything else? The cam sensor is still a 1x but its moved to the timing cover. From the research I've done, running a harness extender will cause either lag or interference issues in the signal. Other main concern is the knock sensors. Do I just splice into the harness right where it goes to the ecm? Running a gen 3 harness on it. Accessories look like they'd work. Shouldn't have to swap over the fbody accessories if thats the case.
When I built the LSX 427 for my 01 car I purchased the LS2 timing and valley cover and I also needed extension harness for the knock sensors and cam sensor. I had to drill and tap for the knock sensors but as for any interference using the harness extenders I've not ran into any issues with this and the engine has been in the car since 2015. Not sure if the LS2 has the same mounting points for the alternator but that's an easy fix. For the knock sensors the harness connects to the engine harness just like the Gen III but the extender harness is long enough to reach down to the sides of the engine block where the new knock sensors went.
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When I built the LSX 427 for my 01 car I purchased the LS2 timing and valley cover and I also needed extension harness for the knock sensors and cam sensor. I had to drill and tap for the knock sensors but as for any interference using the harness extenders I've not ran into any issues with this and the engine has been in the car since 2015. Not sure if the LS2 has the same mounting points for the alternator but that's an easy fix. For the knock sensors the harness connects to the engine harness just like the Gen III but the extender harness is long enough to reach down to the sides of the engine block where the new knock sensors went.
I ran an extension harness for the MAP sensor down along the side of the intake manifold and the passenger cylinder head to move it to the front on the aftermarket intake manifold and the cam sensor extension harness was ran down the drivers side and dropped down around the alternator bracket and connected to the cam sensor on the LS2 timing cover. The original location for the cam position sensor is on the back of the Gen III LS block.
Last edited by 01CamaroSSTx; Nov 27, 2025 at 11:21 AM. Reason: Clarification
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yeah I was just wondering if you ran it under the manifold or somewhere else to get the shortest distance to the rear. Figured that would also keep it hidden. why did you run it above the manifold instead of under?
I don't think there is enough room to run it under the intake manifold with a LS6 intake or Fast intake since the bottom is flat.
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From: Springfield, Arkansas
You are correct that all GTO LS2s used the 24x reluctor wheel on the crankshaft, which is exactly what your 1999 Gen 3 harness and PCM (red/blue connectors) need. They are plug-and-play in this regard.
