Swapping SOHC for DOHC

FutureImportKiller · 09-18-2002, 09:01 PM

Right now I have a 93 SC SOHC motor w/ auto trans. I'm going to be putting a DOHC motor w/ auto trans. Do I need to swap the pcm and wiring harness to put a DOHC motor in my car or will the SOHC pcm work? Any info would be greatly appreciated.

Yobos4vr · 09-18-2002, 09:10 PM

yeah i believe you do have to swap pcm's depending on te year of the dohc if it's obd I or obdII more is involved.

**Ssicarman** · 09-19-2002, 02:11 AM

Yes you will need to replace the PCM from SOHC to DOHC. If for no other reason than the SOHC throttle body PCM won't know what the h*** to do with multiport injection.

wolfman · 09-19-2002, 04:36 AM

It's quite a bit more complicated than just swapping the PCM. You will also need the entire engine wiring harness that runs from the PCM to the engine compartment as your SOHC has a connector for (and only) 1 fuel injector. The DOHC has connector(S) for 4 fuel injectors. Only cars made after 95' when both the SOHC and DOHC got MPFI need just a PCM swap. (Although it MAY be possible on these cars just to reprogram the PCM telling it it's a DOHC...I can't recall if that's possible)

Joeybagodonuts · 09-19-2002, 03:32 PM

its actually quite easy, yuo jsut have to know which dohc harness will fit your early year FUESBOX, thats the trick, only certain year harnes's and pcms from twins will run the conversion as the bottom of the fuse box changed around late 94 or so.
but, you ONLY have to add a twin cam engine, pcm whichinstall in 5 minutes and the proper harness to do this, lots of people try and complicate it and say oh you NEED twin cam gauges or you NEED a twin cam tranny, malarkey, you need a engine, proepr harness and pcm, and its not hard, changing any engine you have to undo the harness anyway, so you have to push the new harness through the same hole in the firewall and mount the twin pcm where the single pcm was, ten minutes, peice of cake.

FutureImportKiller · 09-19-2002, 06:46 PM

So since my twin cam that i'm installing is a 92 model, I need a pre 94 pcm and harness is what you are saying, Joey? If so, you got any PCM and harnesses laying around down thier that are pre 94? How much you sell me one? Also can I use my SOHC auto trans for the DOHC swap, or do I need a DOHC auto donor trans?