Issue with cylinder 4

[rlacasse1]

Ok, here's the problem.

My car has a COP on it. When running the engine sounds completely fine. I can not hear a skip or a misfire whatsoever. However, if I pull off the #4 plug the engine doesn't change at all. Makes me think it isn't firing, but if I can see it arcing when I ground it out so I know it is.

So question is would a bad injector cause this.

 

[darkiller_666]

You say it is running fine? A few things i would try. Touch the the runner of the exhaust manifold from cylinder 4, if its hot then your cylinder is fine. It will be very hot if its working. If its not and you are sure you are getting spark, aka grounded plug wire against the head and it sparks, then pull of the fuel rail. Its only the bolts. Unclip this injector plug harness for cylinders 1-3. Unplug the connector on the coil pack so your not sparking. Have someone turn the car over as you place a rag over cylinders 4 injector. Then check the rag and see if there is fuel. If there is fuel and spark, and you still feel like something is wrong. Do a compression check. Fuel+spark+compression=combustion.

 

[rlacasse1]

Yeah i ground out the wire and i know it it is firing. And the car sound perfectly smooth.

It's just my experience if you take a plug wire off the car will start running crappy and my car will not change at all when you take a plug wire off.

 

[darkiller_666]

I agree it should at least drop in idle. On the other hand i believe you would notice only riding three cylinders. Atleast i hope. If you dont want to burn yourself while testing the Exh mani, while the car is cold take a little bit of oil and rub it on the runner for cylinder 4. Then turn the car on and let it idle. The oil will start to smoke as the manifold gets hot. Again if the manifold is getting hot=combustion. Cold runner on the manifold=no combustion.

 

[rlacasse1]

Ill try checking if it is hot. But is sounds perfect when it is running.