99 s10 Ignition Coil Testing

I recently purchased a new set of spark plug wires, cap, rotor and ignition coil for my 1999 s-10
Ever since I did my truck runs horrible. I noticed that it is worst when it is humid or rained the night before. Last night I went outside in the dark and gently misted the wires, cap and coil with a hairspray bottle full of water. Immediately I saw what looked like a fireworks display going on from random spots in the wires and ignition coil and the top of the cap looked like it had about 100 spots that where arching. Is the equipment faulty? Could it be that I didn’t replace the Ignition control module and it is making all the rest go bad?

How do I test my ignition coil? It has a main post that connects to the cap and two wiring harnesses but I dont know what is positive or neg to test it?:eek7:

I recently purchased a new set of spark plug wires, cap, rotor and ignition coil for my 1999 s-10
Ever since I did my truck runs horrible. I noticed that it is worst when it is humid or rained the night before. Last night I went outside in the dark and gently misted the wires, cap and coil with a hairspray bottle full of water. Immediately I saw what looked like a fireworks display going on from random spots in the wires and ignition coil and the top of the cap looked like it had about 100 spots that where arching. Is the equipment faulty? Could it be that I didn’t replace the Ignition control module and it is making all the rest go bad?

How do I test my ignition coil? It has a main post that connects to the cap and two wiring harnesses but I dont know what is positive or neg to test it?:eek7:


plug wires need be of good quality ...I prefer the dephi wires ..perfect fit with excellant insulation.....

you need to use dielectric grease on the boot ends to keep the water out ...with water and the arcing soon you will have no conducting material in the wires ....whenever the engine runs bad in wet or humid weather it is usually the wires/cap/coil.....carbon deposits make the electrial current flow with ease the more it arc the greater the carbon ..

the coil should be cleaned and the connections checked for corrosion...

Thank you very much I am gonna give it a shot and go get some new wires with the grease. I will let ya know how it ends up

Ok did the wires checked all the plugs and used the grease. It still runs rough. I can see that the wires are no longer arcing but I do see that I am getting a lot or arcing from the ignition coil itself. From the two sides of the coil I can see blue light jumping from the coil to the square steal around the coil. I looked up how to test the coil and from what I can tell with my coil is good. I did notice alot of carbon buildup from the back of the valve cover. ALOT! What I dont understand is that I had no problems before and I decided to change my plugs and tore a boot in doing the job so I had to replace it. After that I am having nothing but problems

Make sure the distributor cap is wired correctly:

http://i561.photobucket.com/albums/ss58/cwhook/97newer43Lfiringorder-Copy.jpg


Arcing at the ignition coil is caused by high secondary resistance in any one or more of the following: spark plugs, wires, cap, rotor, or the coil itself.

What brand and part number spark plugs are you using?
How many miles on them?
What brand distributor cap and rotor are you using?

Ok did the wires checked all the plugs and used the grease. It still runs rough. I can see that the wires are no longer arcing but I do see that I am getting a lot or arcing from the ignition coil itself. From the two sides of the coil I can see blue light jumping from the coil to the square steal around the coil. I looked up how to test the coil and from what I can tell with my coil is good. I did notice alot of carbon buildup from the back of the valve cover. ALOT! What I dont understand is that I had no problems before and I decided to change my plugs and tore a boot in doing the job so I had to replace it. After that I am having nothing but problems

put the old coil back in ....new does not guarantee good in todays world ...get another new coil and recheck for the correct part number on the internet....

so the plug wires stoped arcing ! your almost there ..

Thanks guys I will check that out tomorrow I just got back from work outta town.

Ok, I just got a new ignition coil form AutoZone. They replaced my old one for free. My plugs are autolite. I will check the part number in a few. Wires are Bosch cap and rotor are both duralast also from AutoZone. I did not know how important it was to do OEM and now I spent my money on the ones that I got. The truck runs a little better, but not perfect. It still sputters at lower RPM's or when I am starting from a dead stop. It seems to run fine if I am moving or stepping hard on the gas. I am wondering if my CAT may be plugged because when I changed the old plugs some where very bad and cracked. I am wondering if it had Alot of excess fuel that the cat had to burn up and it may have been that way for a long time

Plugs are autolite double platinum app605

I checked the gap on my one plug that I pulled out it was .055 I think it is supposed to be .060 would that make a big difference?

Ok, I just got a new ignition coil form AutoZone. They replaced my old one for free. My plugs are autolite. I will check the part number in a few. Wires are Bosch cap and rotor are both duralast also from AutoZone. I did not know how important it was to do OEM and now I spent my money on the ones that I got. The truck runs a little better, but not perfect. It still sputters at lower RPM's or when I am starting from a dead stop. It seems to run fine if I am moving or stepping hard on the gas. I am wondering if my CAT may be plugged because when I changed the old plugs some where very bad and cracked. I am wondering if it had Alot of excess fuel that the cat had to burn up and it may have been that way for a long time

with the O2 sensor removed [the hole left open ] go for a test ride ..if the problem goes away the cat converter is damaged causing a restriction ...

I don't like auto lite plugs ...the plugs may be a problem ....cracked plugs mean overheating usually ....detonation / pinging ...your combustion chambers may have excessive amount of carbon deposits ..

Aftermarket distributor caps and rotors don't cut it in a 4.3L, especially Duralast. Check this: http://www.automotiveforums.com/vbulletin/showthread.php?p=6100044#post6100044


Autolite plugs are not a good choice: Hold an AC Delco and an Autolite plug side by side, you'll see the difference with the taper seat and reach. You can't see the heat range, but it's not correct either. And as you found out, they don't come with the proper gap.

1. Pitch the Duralast cap and rotor.
2. Pitch the Autolite plugs.
3. Install AC Delco cap and rotor.
4. Install AC Delco plugs 41-993 with a gap of .060

Hopefully the Duralast coil will work, if not, reinstall the original. With good, (correct) parts it should run better. If you still have problems, we can continue with diagnosis, but number one is get the right parts in it.

Ok I will try both. I still have the original cap and rotor that I took off. They where not bad but just changed with the wires. I will also pop the O2 sensor off and see if that makes any improvement.

k, Just got done messing around with the truck. I pulled the O2 sensor and it did nothing.

I took off the cap, rotor and put my old OEM one back on. Problem seemed to get worse. I did not change the plugs yet but I will do that soon.

I noticed alot of dirt buildup behind the valve cover so I am guessing that it has shot some oil out of it and dirt has stuck to it. I started the truck and removed the hose from the cover, then I placed my thumb over the hole. It did have some vacuum but not to much as I gave it more throttle the vacuum increased. I kept the throttle at a constant and put the hose back in it. It started jumping like it does when I am driving. I took the hose back out and left the throttle at the constant rpm. I slowley covered the hole and I found that I can make the jumping stop by covering about 75% of the hole. If it is fully covered it jumps and If the hose is in it jumps. I am guessing that the valve cover has a leek in the seal. I am going to see if I can get a vacuum tester and see if this may be the root of this evil.

Did vacuum test. Everything came out good. good compression, good seals, good valve's, good CAT.

I don't know what is going on. It seems to be good when the engine is hot.

Anyone got any Ideas?

Did vacuum test. Everything came out good. good compression, good seals, good valve's, good CAT.

I don't know what is going on. It seems to be good when the engine is hot.

Anyone got any Ideas?

since no codes , engine runs good hot , and these items checked are good , replace the engine coolant temp sensor ....low cost ECT...also check that the connector to it is in good condition ...

this can tell computer that the engine is warm when its really cold ,,this will cause a lean condition ..usually hard starts also with this sensor when it begins to get out of normal range..

I just put the cap wires and plugs from my Blazer in the truck it did help the issue but it is still there. I am seeing that when I come down from a fast speed the problem is not present for a few min. e.g. " after getting off the Interstate" or just on a road with not many cars. I am in FL so alot of the roads here are 60mph. It is a issue mostly where I am going from a stop to a start that it happens. It is gone if I am crusing before I have to stop. If I am in traffic and dont really get above 30mph or 3000 rpm it keeps getting worse. Almost like I am getting alot of fuel and it is having a hard time burning it up.

OM was correct again. Got new wires and new cap and plugs. Runs perfect