leonpiper69

iTrader: (3)

i put this in the right section, but no one over there knows how?


basically i think i have a bad coil and want to make sure.

here the link if anyone wants to see
https://ls1tech.com/forums/generatio...test-coil.html

mmmchickenboy

You can measure the primary and secondary resistances and compare them with the specifications for the coils you have. But it's been my experience that that test doesn't always expose a bad coil.

Another option is to move the coil to a different cylinder and see if the symptoms follow the coil.

spacemanspif

iTrader: (5)

Go with chickenboy's advice. I've only done it on a running vehicle with stock engine but the hand held scanners that read check engine lights will tell you what cylinder is mis-firing and setting the code. Delete the code, move the coil and run it until it sets the code again...if the misfire is now on the cylinder you moved the suspect coil to, then you have a bad coil.

leonpiper69

iTrader: (3)

i appreciate the suggestions but as i stated the engine is out of the car and on the stand. i guess i could trying measuring stuff. how do i know wich pins to measure?

and the computer never showed a misfire, i dont think i deleted that code. my engine light was pretyy much always on but it was for the fuel tank presure and i told the computer not to report that but it still kept coming up?

but like i said, it never registered a misfire. so before i put this motor in another car i want to figure out for sure what was wrong with that cylinder, its either spark or fuel, but i dont know how to test for a bad injector either?

and from the pictures i posted, i'm not sure if one can tell if its lack of spark or lack of fuel. im guesing but i think with how clean the plug is there was fuel but no spark?

mmmchickenboy

Seeing as all Gen III/IV engines are OBDII, the PCM's will set codes for cylinder misfires. If you never got a code, then I wouldn't worry about it. It sounds like you're just going off of the condition of the spark plug. I would move the suspect coil to an easily accessible cylinder in case it is indeed bad to make R&R later on easier. This isn't a FORD, coils are easy to change, and I wouldn't worry about it until you get it running again.

mmmchickenboy

After looking at the picture, I would suggest replacing the coil regardless, as it looks broken.

leonpiper69

iTrader: (3)

actually im not just baseing it on the condition of the plug. im basing it on the condition of the plug, plus the condition of the coil (its cracked at the connector) plus the lack of carbon in the exhaust port plus the fact that the motor always ran waaaaaayyyyy rich.

leonpiper69

iTrader: (3)

i plan on it. i just want to verify it is the problem so that down the road i dont end up chasing problems because it turned not to be a bad coil or something. just really want to know for sure. you were saying i could measure the 2 sides of the coil, which pins are which?

mmmchickenboy

After finding and looking at a wiring diagram, these coils appear to have transistors or something inside the coil which disables you from measuring the primary resistance of the coil. You can still measure the secondary resistance by measuring the resistance from the ground wire (brown maybe? not sure on that) to the conductor inside the tower where the spark plug wire goes. The value will be in thousands of Ohms, probably between 5kOhm and 15kOhm. We need to know exactly which coils you have to get the specification.

leonpiper69

iTrader: (3)

sounds like it might be easier to find someone with an ls out here in pa to let me put this coil on there car and see if it doesnt work..... oh wait..... it just dawned on me, my sierra has a 5.3 in it!!!!! this actuall just dawned on me while typeing this. i can just put it on my truck to test it. sweet!

mmmchickenboy

lol yeah that would probably be easier