Running on 3CYL need help!!

[Lord Umoja]

This afternoon my KA started running on 3 cyl. The front cylinder has stopped working. I checked the spark plug and it sparked fine. I replaced the fuel injector and it ran great for about 30 min and then after parking the car for an hour, it's back on 3 cylinders. It is rough as hell below 1k rpm. Seems to smooth out or run on all 4 (can't tell) as soon as the motor goes over 2.5k. It is ONLY cyl 1 running poorly, the car doesn't react at all if I pull the spark plug or injector connector during idle on cylinder 1 but nearly dies if I do anything to the other three. In the 20 minute drive home after it started running on 3 cyl again it some times felt like it was running on all four but it was for seconds at most. Im really frustrated. I need this car to get to work and have no other rides. Any help would be greatly appreciated.

[Lord Umoja]

Oh one other thing. No dash lights at all even when it is stumbling and stuttering. No CEL or anything.

[krash]

Theres nothing we can really help you with, you just have to get in there. I ended up replacing the fuel rail, 4 injectors, ECU, dizzy, plugs, wires and fuel filter (not in that order), before the problem went away on my sister's car

[asoomal]

Go over your grounds, add a couple as well.

If you leave the key to ON, with the car NOT running, with the distributor in your hand can you hear each injector click while turning the shaft with your hand?

[Lord Umoja]

So here is the update. It's running better but still really only on 3 cyl. So far I've replaced:
Fuel Injector
Spark Plugs
Plug Wires
Rotor
Cap

Checked Compression, 160psi on a cold engine. Too concerned about running it up to temp when I'm only on 3 cyl. The new injector clicks with I supply power to it from a probe. I think its either wiring issue in the injector harness, something dmaged/colgged the fuel rail, or my ECU is dying. Any thoughts?

[asoomal]

Check if you're getting spark or fuel to cylinder 4. I want to know whether it's a fueling problem or spark, just hook up a spark plug tester to cylinder 4.

[biggie]

Check to see if that fuel injector is firing? Swapped the ECU for a barrowed one?

[Lord Umoja]

Cylinder 4 (Assuming that cyl 4 is the one closest to the firewall) is running strong. The engine runs horrible when I pull the plug wire OR the Injector plug on cylinder 4. It seems to be an issue confined solely to cyl 1 (Closest to the radiator). The spark in cylinder 1 is strong now that I have replaced the dizzy parts, plugs, and wires.

Inkector trips when I supply a voltage to it outside of the rail.

As for the ECU, I have a spare but its from a manual car. I assume that is going to cause issues right?

[asoomal]

Is the injector getting a signal? See if you can borrow a noid light.

[Lord Umoja]

So dumb question I have a spare ecu from a manual car. Will I be able to test the engine with that and be ok as long as I don't try to drive on it?

[GTR PrYdE]

I've had many injectors fail on me throughout the years. The best bet i've had is using an ohm meter to check resistance. It should be 10-20ohm IIRC, and when they fail it goes above 1000...

You can also pull the rail with the injectors intact and try starting the car, to see if it sprays fuel (be very careful when doing this, use shop rags or towels for easy clean up!)

[Lord Umoja]

I triggered the injector itself. It's brand new and clicks when I put 12v thought it.

At this point I'm thinking its wiring or ecu. I've diagnosed everything else save a clog in the fuel rail.

[asoomal]

Check if the ECU is grounding the injector.