3rd piston isn't firing correctly

[Brandmeister]

I just recently got a KA24DE swapped into my previously SOHC 1989 240 hatch. The engine seemed like it was running fine, but then the 3rd piston seemed to stop firing -at lower RPM's at least. I know it is the third piston because when you lift up the third spark plug wire the engine doesn't bog down while the other pistons do when you take out their wires. I have replaced the third injector, the wires, and the spark plugs and still it doesn't run much better. It seems to run a little better after I replaced the injector, but it is still not running quite right. I'm pretty stumped on what is going and any advice would be appreciated.

[1unar3clipse]

check all your injectors and spark plugs/wires.after those all come up clean check your ecu against a known working one, also check you have all your grounds from engine to chasis.

[Brandmeister]

Well, I know for a fact it isn't the wires because I've swapped them around with the others and the 3rd piston still gives me problem. I know it isn't the Spark plugs because I replaced them. I'm thinking it is probably the injector. Even thought I replaced it, it came off an old parts car I have so their is no guarantee that it works. Perhaps I should consider just getting a brand new one or trying another injector. I'm pretty sure all the grounds are attached.

[redtop91]

Check compression, spark, and fuel. It'll be one of those for sure. On my SR, when I was having specific cylinder problems it was spark which is relatively easy to fix with coilpacks but with a distributor that's a different story. I'd bank on anything in the spark line.

[Brandmeister]

Well, I'm pretty sure it's the injector not spraying correctly, but I'm not sure why. Maybe the replacement one I used was bad as well. Like I said, I replaced the spark plugs and I know the wires are working for sure. I haven't done a compression test yet.

[240FeVeR]

switch injectors from another cylinder and put it on #3, if #3 starts running fine and the problem moves to the other cylinder, but a new injector.