Differnce between Blktop O2 and Redtop O2?

[Sileighty_85]

you can use a Black top harness on a red top but you also need to use the ECU for that harness cuz the Black top ECU pin outs are little bit differnt so if your using a black top harness make sure you use PFC for the Blacktop

[unicoladron]

think about this for a second..
MAYBE! whoever originally had your engine and my engine were friends..

cuz i'm pretty sure i have a redtop, but i have a blacktop vc, and i had the skinny o2 sensor with the skinny dump pipe, and no fins on my head. so let's trade and get everything back to normal!

[SHIFT_*grind*]

Originally Posted by Sileighty_85

cuz the Black top ECU pin outs are little bit differnt

Incorrect, unless you're talking about the late model (Kouki) blacktop SR (or possibly the S14 blacktop as well). ECUs from earlier S13 blacktops (94-96) can be used with S13 redtop harnesses without issue. It's the 97-98 S13 blacktop type X ECU that requires a 97-98 wiring harness because of the different pinout.

Also, I've received conflicting information on whether or not a fat O2 sensor will work properly with a redtop ECU. Most people say that it'll work fine, still others say that it won't. It will definitely work, but I can't say for certain that it will work quite as well (meaning, your gas mileage may suffer etc) as a skinny sensor.

I just installed a new skinny sensor to run on my redtop ECU, Bosch part #13791 for an 86 NA 300ZX; I'll try to remember to let you know how it works out =P

Also, if you end up buying a new skinny sensor, do NOT just order one for an '87 300ZX turbo as it says in the FAQ. At least not if it's a Bosch. You'll end up with a square plug instead of a flat one, which could work...if you feel like cutting the plug off and soldering the wires yourself.

[garagelu]

Just because it has fins on the head doesnt tell you everything. Late model redtops also have fins on the head. The accurate way to check redtop/blacktop is by looking at the pistons and see if they are 54c or 79e. Also the a/c compressor and bracket can tell you also.

[jskateborders]

Originally Posted by Sileighty_85

you can use a Black top harness on a red top but you also need to use the ECU for that harness cuz the Black top ECU pin outs are little bit differnt so if your using a black top harness make sure you use PFC for the Blacktop

Only j4 and j5 ecu's give you any real problems. Most black/redtop ecu's are pinned the same though