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I thought that this discussion would be an important addition to Z31Performance.com, since there is alot of ECCS swapping going on between Z31's. From a general inspection of the ECCS wiring diagram in the FSM, it is very clear that the fuel injector wiring between turbo and na ECCSs do not follow the same pattern. If one was to install, for example, a turbo ECCS in an orginally non-turbo Z31, then changing of the wiring pattern on the ECCS harness is needed for correct operation of the fuel injectors and engine.
We all can agree that the Z31 ECCS uses simultaneous injection and group injection, in the former, fuel is injected into all six cylinders simultaneously twice each cylinder cycle. In other words, pulse signals of the same width are simultaneously transmitted from the ECCS to the six injectors two times for each engine cycle. In the group injection system, six cylinders are divided into two groups and fuel is injected into each group seperately once each engine cylce.
When any of the following conditions are met, fuel injection shifts to simultaneous injecton from group injection:
Engine speed is more than 3000rpms.
Injector pulse duration is more than 6.5ms.
Cylinder head temperature is below 60*C or 140*F.
When starting.
Having the fuel injectors wired up incorrectly will essentially make the fuel injectors stay in simultaneous mode for the whole range of engine operation. This will effect partial throttle operation, cruising*, cold starts, hot starts by making the engine run double the enrichment than intended.
*may not effect cruising if the added fuel enrichment is within the ECCSs scope of adjustment. In other words, the ECCS, using the 02 sensor, has a limit of how much it can change the enrichment from the base enrichment in order to acheive stoic.
From my inspection of the FSM, when converting from a 84 turbo ECCS to 84 NA:
Turbo-------NA
1------------no change
2------------3
3------------5
4------------2
5------------4
6------------no change
There may be differences in the other years, so examination of the applicable FSM is strongly suggested in order to get the swap right.
We all can agree that the Z31 ECCS uses simultaneous injection and group injection, in the former, fuel is injected into all six cylinders simultaneously twice each cylinder cycle. In other words, pulse signals of the same width are simultaneously transmitted from the ECCS to the six injectors two times for each engine cycle. In the group injection system, six cylinders are divided into two groups and fuel is injected into each group seperately once each engine cylce.
When any of the following conditions are met, fuel injection shifts to simultaneous injecton from group injection:
Engine speed is more than 3000rpms.
Injector pulse duration is more than 6.5ms.
Cylinder head temperature is below 60*C or 140*F.
When starting.
Having the fuel injectors wired up incorrectly will essentially make the fuel injectors stay in simultaneous mode for the whole range of engine operation. This will effect partial throttle operation, cruising*, cold starts, hot starts by making the engine run double the enrichment than intended.
*may not effect cruising if the added fuel enrichment is within the ECCSs scope of adjustment. In other words, the ECCS, using the 02 sensor, has a limit of how much it can change the enrichment from the base enrichment in order to acheive stoic.
From my inspection of the FSM, when converting from a 84 turbo ECCS to 84 NA:
Turbo-------NA
1------------no change
2------------3
3------------5
4------------2
5------------4
6------------no change
There may be differences in the other years, so examination of the applicable FSM is strongly suggested in order to get the swap right.
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