I want to know if I can use a 1981 CIS in place of the 1980 CIS. Car is stock 1980sc with original motor,ecu et. The reason the 81 CIS in the photo above had the 6 plug was because I put it on there last year and forgot I did it.All I want to know is if I can use the 12 pin 81 CIS in MY 80 6 pin car without too much trouble.

The two systems have enough differences that you need to swap all of the different components. Mixing and matching is never a good idea. The first step in that direction is to understand what the differences were, so I'd suggest getting copies of the technical training documents for both years, a copy of PET, and do a few nights of studying.

You can also consider keeping what you have and fixing it. Just because the previous owner said the system was bad doesn't mean **** to me. He could have been an idiot, at the very least probably didn't fully understand CIS anyway, and there's nothing in a CIS system that can't be fixed. The problem is most people short-cut the diagnosis, trying to find the one bad part before understanding how everything is working. If the symptom is this, the cause must be....

The other side of the coin is that you have no idea what condition the 1981 components are in; there could be as many problems there as what you have.

JR

Steel injector lines.
Cold start fuel mixture distributor in plenum.
Shear-off screw plugging the mixture control hole.
Acceleration enrichment via O2 sensor, which requires:
Additional throttle microswitch
Temp switch in crankcase vent cover
Extra control unit for enrichment function
Different control unit with connections for above
Wiring to accommodate the above
Different WUR

In addition, there was a different fuel pump, fuel filter, fuel accumulator and a new cat.

No difference.... :rolleyes: why give this advice?

JR

Thank You