CJ0920

I just dropped the LS Motor out of my 94 teg, and dropped a 2000 gsr motor. I curently dont have the gsr ecu i still have the ls ecu which is obd1. I need help to figure out how the vtec will work..Do i need a obd2 ecu w/a piggy back....?????Im clueless....i want vtec!!!!

Fabrik8

The easiest way to go is to get a JDM OBD1 P72 (GSR) ECU. This way you'll only have to run whatever wires you might not have already, like vtec, knock sensor, etc. The reason I say a JDM ECU is that the OBD1 USDM P72 ECUs are a different secondary butterfly (IAB or dual runner intake manifold, whichever term you prefer) polarity than the OBD1 JDM and all OBD2 P72s. You can use a USDM P72 but you'll have to use a relay or something to switch the polarity to what your OBD2 engine wants. For some reason this difference in the ECUs is not common knowledge, and there are most likely a shitload of swaps out there with non-working IABs. So really, I'd get a OBD1 P72 which will plug right in to your harness, and then just run the few wires you need. Just be prepared to use a relay if necessary on the IAB.

Completely disregard this rant if you're not using the secondary runner manifold, and are using a Skunk2 manifold, etc..