I have an issue with a 97 5.4L that has a #4 cylinder engine missing code. I have swapped the COP with another cylinder which caused no change. The same cylinder is missing. I checked the ohms on the injectors and they are very close with-in .1 difference.

I then checked the voltage of the COP connector (with it unplugged/key on) with a DVM and found that #4 had 10.03 volts and then checked # 1 the same way and found it to be at 11.98 volts. I then removed the COP and with it plugged in...started the engine and no spark. I'm not sure what to do next. I was thinking about a computer issue. any Ideas.

I read the forums for a couple of hours and really haven't found any other issues the same....simular though. Thanks!

This look like a great thing you have going here.

 

How many miles are on that 5.4? It may sound dumb but did you use a spark plug when you removed the COP to check for spark? Try swapping plugs to see what happens? Then swap COP and plug to another cylinder. At that you will have tried all the swap combinations. Check other COP's voltages to see if that 10.03 volts is low.
I'm not sure if the variance makes a differance anyway. Some one may be more informed that I so hang in there and you'll get the answer. This site has helped me more than once.

 

It has 157,000 on it. it's probably a little harsh but I use a screw driver to make a gap between the coil and ground to check for spark. Clearly I should have used a spark plug to provide the proper resistance. This started with a spark plug change last summer.

The owner of the vehicle is disabled and I help him with repairs when I can. We put off changing this last plug as it was packed with hard crud and I suspect I had something else I needed to do.

Anyways, the truck developed a miss a few days ago so he went to Azone and they checked the codes. it showed #4 miss...the one we didn't change. I used PB blaster in the plug hole and a thin wire with a flat end to dig and remove the crud. After a few hours I was able to remove the plug. The plug had deep pits in the metal around and below the hex part of the plug.

The new plug didn't change anything. The swapping of coils didn't change any thing either. We did change all the boots between the plugs and COPs.

I did not check multiple coil connector voltages though I will check that today.

Thanks for the help!

 

still having problems with this truck...I checked the other COP connector voltages and all but the #4 are 12. volts. #4 being 10.08. Any one have any Ideas. I'm a a loss here.

Thanks