When the check engine light is flashing on an OBD2 vehicle it means that damage is occuring to your catalytic converter. The most common thing is of course a clyinder misfire. You were actually doing a cylinder balance test when you were unplugging the injectors and noting the engine speed difference. You should hook up a tach and write down each cylinder drop when you unplug the injector. When you find the one that is misfiring (no drop) you need to ascertain whether it is the injector, PCM or ignition. Use a screwdriver and hold it to the injector and to your ear (make sure you do it to one that you is good). Does it click? No... At this point you will need a digital VOM (Volt Ohm Meter) It needs to be digital because it has to be a high impedance meter. The analogue ones run the risk of damaging the PCM. There are 2 wires that go to the injector, one power and one ground. The switching from the PCM is done through the Injector Drivers which are simply transistors. These drivers simply make a connection to ground when it wants the injector to fire. So, power is always on (with ignition to run) and the actuating of the injector is done on the ground wire. Check for power with the DVOM on one of the wires (can't remember the colour..) but one should have 5volts (or maybe 12...again can't remember off hand, but one or the other) Is there power? No, check for a problem with the wire of out of the PCM. Yes?... Use a test light and connect the clip to battery positive and the other end to the unplugged end of the connector ground. When the engine is running is it flashing? If it is flashing then the drivers are working properly. If it is on constant then you have a problem with the driver and it is either a short to ground of the wire or the PCM itself. If it is off then check for an open in the wire between the connector and the PCM. If all of that is working fine then check the injector itself. Compare the resistance between a known good one and the suspect one. But actually if the circuit itself is working fine then it is obviously the injector.
First thing though is to ascertain if it is the fuel or the ignition.
Hope this helps
1992 Bonneville SSEi
White, grey Leather interior.
Tinted windows and blackouts on headlights.
Custom high flow exhaust, Everything replaceable - DONE
300 000 kms original engine, tranny 2 rebuilds.
Playboy Bunnies Embossed in Tint. Oh Yah!
Ever Seen a Polar Bear in a Snow Storm?