As per my knowledge ...
- 1st gen is the most basic version.
- It has distributor with built-in igniter or you can say igniter is located with in the distributor.
- The distributor is adjustable i.e. you can manually advance & retard the timing by adjusting it.
- Distributor has 2 wiring harnesses/connectors. One has 2 wires & Second has 4 wires
- It doesn't have CKP sensor i.e. camshaft positioning sensor.
- It has single wire oxygen sensor on the exhaust manifold.
- OBD1 ECU system
Now comes 2nd gen
- It also has distributor but igniter is not built-in. Igniter is separately installed on the passenger side strut tower behind the airfilter box.
- The distributor is non-adjustable i.e. you cant advance or retard the timing.
- Distributor has single wiring harness/connector which has 4 wires.
- It has CKP sensor located on in the timing belt cover & you can see its wires coming out of timing belt cover & can see the harness right above the alternator.
- It has 4 wire heated oxygen sensor.
- It also has OBD1 ECU system.
- I believe mine 7a is also 2nd gen.
In 3rd gen
- Almost everything is same as 2nd gen except coils i.e. it has coils instead of distributor.
- ECU is a bit smarter and has OBD2 system.
- It has 2 oxygen sensors i.e. pre-cat & post-cat.
P.s. Some regions/countries also introduced lean-burn models of 7afe due to strict emission requirements.
Thats all I got to understand about 3 gens of 7afe till now, I might be wrong somewhere, you can correct me.
