Unfortunately my original engine blew up due to buying a lemon. I was just wondering if anyone had any knowledge on the differences and similarities between the 93 and 95 JZ engines since I have purchased a 95 engine. I heard that the earlier 93-94 injectors are batch fired, making me think the 95 is sequential fire. Another difference I have noticed is the alternator plug being a part of the body harness instead of the engine harness on the 95. I did swap the 93 engine harness over to the 95 because of the alternator mishap, and all the plugs match. I do only have the 93 ECU. I'm guessing I should just swap my 93 injectors and look into the fuel pump ECU, but I'm pretty sure it won't be that simple if Toyota revised multiple things. If worse comes to worst, I do have 2 wiring harnesses, and I can make my own harness if any other complications are apparent. Thanks.

 

There are no differences in the ignition firing system from 1992-1997. It is with the 1998-2000 2JZ-GE VVT-i engines that the firing system changed with coil packs vs an older fashioned distributor ignition.

There are, however, slight differences with all the naturally aspirated 2JZ ECUs: 1992-1994, 1995, 1996 and 1997. There may not be so much variance with Federal Emissions 49-state ECUs but those years are all different for any California Emissions ECUs between each of those model years.

Mostly this has to do with a change from early type two wire O2 sensors to four wire heated O2 sensors which the Cali Emission models got a bit sooner than Federal starting in 1995. In 1996 all SC300's got the four-wire heated O2 sensors.

Also Cali Emission SC300's got a 3rd 4-wire O2 sensor on their #2 catalytic convertors from 1992 onward wheras Federal Emission SC300's didn't standardize that until the 1996 model year.

Also worth noting is that no SC300's (regardless of being CA or Federal emission type) had a crankshaft angle sensor until model year 1996. Use of that continued through the final 2000 model year.

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The engine itself can be swapped over if replacing a 1993 long block with a 1995 long block. However I do recommend swapping over your entire original 1993 engine harness just to keep everything less complicated. There were no major wiring changes from 1992-1994 but minor changes would be present in a 1995 engine harness. This would be especially so if the new engine comes with a Cali emission 1995 harness which you do not need to install onto a 1993 Federal SC300 chassis.

Also if you're doing all this use it as a good opportunity to inspect the original wiring harness and repair and replace any broken or frayed wires or brittle/broken connectors before getting to the installation phase. Better to cover those bases now before everything is installed in the car

 

Thanks a lot; this relieved a lot of my stress. I hate wiring, but it is rewarding when it's finished, at least. Also, you might as well be the designer of this car; you have helped me with so many issues even on other peoples threads you have commented on.