#1 cylinder not firing right

[ADrewzki]

When the car is running, #1 cylinder isn't firing all the time. It'll spark for about 1/2 second normally then quit for a second, then maybe spark once or twice, then quit. I used a timing gun and watched for the light in this case. It doesn't matter if the car is cold/warm or if it's been started up/previously running. I've replaced the CAS with another used one that works (not ruling this out though). It's got new wires, new plugs, new ignition coil pack, new power transistor pack. The only other things that I can think of is that there's a faulty wire to the transistor pack from the ECU or the ECU itself is faulty in some way. All the other cylinders fire and pulse perfectly. It's just #1 that's been giving me issues. Anyone have any ideas?

-Drew

 

[blue1]

Not sure if this is any help mine was doing the same and it ended up being the wire to the number one fuel injector connector had slipped out a bit!. you figure it out, i thought it was the ignition side problem aswell

 

[ADrewzki]

Checked the wires and they seem alright. I did a resistance check on the injector itself and it showed 2.4 ohms which is in spec as well. Here's the troubleshooting I did today. The car has a 6-bolt in it so I've switched around pins 1,2,14,15 on the ECU. I switched them back around to their original positions. I figure if the ECU is sending out no signal (or a crappy signal), the problem should follow the wire. Started her up and the problem is still local to cylinder #1. I think that rules out the ECU. Might be wiring somewhere from the ECU to the injector or the injector itself is starting to flake out. Can anyone else think of something I've missed? Is there a way to test the wiring from the ECU to the injector?

 

[blue1]

Apart from putting an ohm meter on the wire at the injector end and then at the harness connector pin at the ECU to check the continuity, i think you can bridge the wires at the injector with a test light and watch it flash when the in jector fires

 

[ADrewzki]

I'll see if I can find one of those lights that light up when there's current sensed in the wire. I really really hope it's not the wire. Having to run new wire doesn't seem like a very pleasant evening.

 

[ADrewzki]

So I finally fixed the problem. After replacing the coil pack, transistor pack, and even after buying another ECU, I went to get a noid light from the local store. The guys there and I were shooting the breeze and one of them said he had the L part of the spark plug ground itself out near the bottom. Less than a week old and gapped properly but I figured, "Heck. Might as well check." Sure enough, for some reason the L part of the spark plug had bent itself upward toward the electrode and there was a 0.000005" gap. It wasn't totally grounded out but the spark was definitely weakened to the point where it wasn't idling correctly. Put in a new spark plug and problem went away. ECU + coil pack + transistor pack = ~$400. Spark plug = ~$2. I tell ya, I was so happy it worked that I almost don't feel like an idiot.